Camp. Biochem. Physiol. Printed in Great Britain
Vol. 102A,
No. 2, pp. 285-287, 1992
0
$5.00 + 0.00 0300-9629/92 1992 PergamonPressLtd
D-GLUCOSE TRANSPORT ACTIVITIES IN ERYTHROCYTES AND HEPATOCYTES OF DOGS, CATS AND CATTLE TOSHIROARAI,* TSUKIMIWASHIZU,T~SHINORISAKO, MINORUSASAKI~ and SHIGEKATSU MOTOYOSHI Department of Veterinary Biochemistry, Nippon Veterinary and Animal Science University, Kyonancho, Musashino, Tokyo 180, Japan; tDevelopment Research Laboratories, Banyu Pharmaceutical Co. Ltd, Manuma, Saitama 360-02, Japan (Received 25 September 1991) Abstract-l. The activities of D-glucose transport and hexokinase were investigated in erythrocytes or hepatocytes of dogs, cats and cattle. 2. The mean o-glucose transport activity in erythrocytes of dogs was 6.0 nmol/min/mg protein, half the value of hepatocytes. 3. The activities of D-ghCOSC transport in erythrocytes and hepatocytes or hepatic hexokinase of cats were about one-third of those of dogs. 4. Cattle with low blood glucose concentrations showed considerably low activities of D-ghCOSe transport and hexokinase, about one-third of those of dogs. diet (Canine p/d, Hill’s Pet Products, KS, U.S.A.), eight mixed-breed cats (four female, four male; 3-5 years old) fed on a commercial diet (Science Diet, Hill’s Pet Products, KS, U.S.A.) and eight lactating cows (3-5 years old) maintained on a diet of grass supplemented with good quality hay and concentrates. Hematological and serum chemistry values of animals examined were all within normal ranges.
INTRODUCTION Circulating serum glucose concentrations are maintained primarily by the balance between uptake of glucose into peripheral tissues and storage by or release from the liver (Ferrannini et nl., 1985). Transport of glucose into the cells is the first step of glucose utilization (Ciaraldi et al., 1986). The transport system for glucose has been extensively studied in erythrocytes, adipocytes and many other cells (Elbrink and Bihler, 1975; Mueckler et al., 1985). It has been reported that all mammalian cells take up glucose by facilitated diffusion catalysed by an integral membrane protein (Kasahara and Hinkle, 1976; Wheeler and Hinkle, 1985). On the other hand, the blood glucose concentrations of herbivorous cattle are low compared with those of dogs as omnivorous animals, and the regulatory mechanism of glucose utilization in cattle is greatly different to that of monogastric animals (Ballard et al., 1969, 1972). It has been reported that some differences between omnivorous dogs and cats as carnivorous animals, are observed in glucose tolerance, insulin response and incidence of glycosuria (Chastain, 1981;MoiseandReimers, 1983;Mattheeuws et al., 1984). It is expected that dogs, cats and cattle have different regulatory mechanisms of glucose utilization adapted to their respective feeding habits. In the present study, glucose transport activities in erythrocytes and hepatocytes or activities of hepatic hexokinase, which catalyses the first step of glycolysis, were measured and investigated in dogs, cats and cattle. MATERIALSAND
METHODS
Animals The following animals were used: eight mixed breed dogs (four female, four male; 4-6 years old) fed on a prescription *To whom all correspondence
should be addressed.
Collection of blood and liver samples Blood was withdrawn from the jugular vein into a heparinized tube. Plasma was recovered by centrifugation and stored at -20°C. The dogs and cats were premeditated with 0.05 mg/kg acepromaxine maleate (Tech America, KS, U.S.A.), and anesthesia was maintained with halothan. Liver samples were taken from the anesthetized animals by laparotomy. Liver samples of cattle were taken by percutaneous needle biopsy. Plasma membrane isolation of erythrocytes and hepatocytes Ghosts were prepared from animal erythrocytes and washed with EDTA and NaCl (Kasahara and Hinkle. 1976). Washed ghosts and removed liver tissues were homogenized in 4 volumes of 10 mM Tris-HCl buffer. DH 7.5. containinn 1 mM EDTA with a Teflon homogeni&.‘Plasma membrane fractions were isolated by the method of Belsham et al. (1980). The collected plasma membrane fraction was washed and finally resuspended in the reaction buffer (0.25 M sucrose, 20 mM Tris-HCl, pH 7.5, 1 mM EDTA) to 1 mg protein/ml, and stored at -80°C until it was assayed. D-Glucose transport activity assay D-Glucose transport activity was measured in the plasma membrane fractions of erythrocytes and hepatocytes prepared by the modification method of Robinson et al. (1982). Briefly, 60 pl of a solution containing 1 mM D- 1-[‘HIglucose (lOO@i/ml, NET-050, DuPont, DE, U.S.A.) and 1 mM L-1-[ “Qlucose (25 &i/ml; NEC-478, DuPont) in the above reaction buffer were added to 60 ~1 of plasma membrane fraction suspended in the same buffer, respectively. The resultant suspension was incubated for 2 min at 37°C and 1 ml of cold stop solution (2 mM HgClJlOmM Tris-HCl, pH 7.5) was added to terminate the reaction. The mixture was immediately filtered by suction with a piece of Millipore GSWP membrane (0.22pm in pore size; Nihon
285
Tosmao AIW et al.
286
Millipore Kogyo K.K., Yonezawa, Japan), which was placed in a filtration apparatus. The test tube containing the reaction mixture was washed once, and the filter membrane was washed twice with 1 ml of the stop solution. The f&r membrane was placed in a scintillation viat, which was then filled with 10 ml of Aquasol- (DuPont), and mechanically shaken for 1 hr. The difference in the amount of D[)H]glucose and L-[Wlglucose collected by the above filtration was assumed to represent the carrier-mediated o-glucose transport activity, which was expressed as nmoles per min per mg protein.
Table 2. Activities of o-glucose transport and total hcxokinase in hepatocytes of dogs, cats and cat&s D-Glucose transport Htxokinase
Dog (5) 11X5*4.0 48.8 f 10.5
#it (St 4.0 f 1.2. 18.7 & 7.9’
Cattle (3) 3.9 f 1.1. 17.5 + 6.7’
Values represent the means & SD (nmol/min/mg protein). Number in parenthesis indicate the number of animals. *Significantly different from the value of the dog (P < 0.01).
Activities of D-glucose transport and hexokinase in hepatocytes of dogs, cats and cattle are shown in Table 2. The D-glUCOSe transport activity in hepatoA part of original homogenate of liver tissue was cencytes of dogs was 11.6 + 4.0 nmol/min/mg protein, trifuged at 15,OOOgfor 30 min at 4°C and then at 100,OOOg which is almost twice of the value in erythrocytes. for 30 min at 4°C. The resulting supernatant was used as Those of cats or cattle were significantly lower hepatic enzyme extract for hexokinase activity assay. Total (P < O.Ol), one-third of the value of dogs. The total hexokinase activity was determined by the method of hexokinase activity in hepatocytes of cats or cattle Bergmeyer et al. ( 1974). The reaction was carried out in the was significantly lower than the value in dogs. micioc&ette, which contained as final concentration, Hexokinase activity assaq
40 mM triethanolamine. OH 7.6. 0.9 mM NADP. 8.0 mM MgCl,, 0.64 mM ATP, 0.6 units/ml of glucose-&phosphate dehydrogenase (Oriental Yeast Co., Tokyo, Japan) and 200mM glucose. The reaction was started by addition of 0.02 ml of enzyme extract, and the absorbance of NADP at 340 nm was measured spectrophotometrically at 23-25°C. The activity is expressed as nmoles of NADPH produced per min per mg protein. Other analysis
Glucose concentrations in whole blood were measured by a glucose oxidase method (Huggett and Nixon, 1957). Plasma insulin #n~ntrations were determined by a micro ELISA sandwich method (Arai et ul., 1989). The protein concentrations in the plasma membrane fractions or enzyme extracts were determined by the method of Bradford (1976) using bovine serum albumin (Wake Pure Chemical Industries, Osaka, Japan) as the standard. Stalistics
Each calculated value was expressed as mean f SD, and the difference between means was analysed by Student’s t-test. RESULTS Blood glucose and plasma insulin ~on~entra~ons and D-&CO%? transport activity in etythrocytes of dogs, cats and cattle are shown in Table 1. The mean
blood glucose concentration of dogs was 100 mg/dl; the mean value for cats was a little lower. The blood glucose concentrations of cattle were significantly lower (P < 0.01) than those of dogs. The plasma insulin concentrations of dogs, cats and cattle were about 20pU/ml. the mean D-glucose transport activity in erythrocytes of dogs was &Onmol/min/mg protein. The activity of cats or cattle was about 2.0 nmol/min/mg protein, which is one-third of the value of dogs. TabIe 1. Blood glucose and plasma insulin ~n~ntratio~ aad ~-glucose transport activities in crythrecytes of dogs, cats and cattle Dog (8) Cat (8) Cattk (8) 60*7* Blood glucoac(mg/dl) lMf&ts 84i9 18*6 22k9 Plasma insulin (rU/ml) 20f8 D-Glucose transport 6fl.4 1,9f0.7* 2.1f0.9’ (nmol/min/mg protein) Values represent the means f SD. Numbers in pamathesis iadicate the number of animals. *Significantlydifferent from the value of the dog (P c 0.01).
DISCUSSION
D-Glucose transport activities in erythrocyte or hepatocytes of dogs were almost the same as values reported previously for humans or rats (Kasahara and Hinkle, 1977; Ciaraldi et al., 1986). The present study showed that D-glucose transport activities in erythrocytes or hepatocytes of cats and cattle were considerably low, about one-third of those of dogs. Cats also showed low activities of hepatic hexokinase. Hyperglycemia is observed more frequently after stress or infusion, with lower concentrations of glucose in cats than in dogs. It has been reported that glucose tolerance of cats is inferior to that of dogs (Kaneko et al., 1978; Nelson et al., 1990). These results may suggest that erythrocytes or liver tissue of cats can utilize less glucose than dogs. Low activities of D-glucose transport or hepatic hexokinase are considered to be correlated with lower ability of glucose utilization observed in cats than in dogs. Although ruminants eat large amounts of carbohydrate consisting mainly of cellulose and hemicellulose, these polymers are degraded in the rumen to yield acetate, propionate and butyrate, and very little glucose is absorbed from the gut (Katz and Bergman, 1969). Glucokinase (type IV hexokinase) with a high Km value for glucose is absent in liver tissue of cattle and glycolytic ability in liver tissue of cattle is very low complared with that of monogastric animals (Ballard et al., 1969). In the present study, total hexokinase activities in liver tissues of cattle were about one third of those of dogs. Low D-@uCOSe transport activities in erythrocytes or hepatocytes are considered to correspond with low metabolic rates of glucose utilization in cattle. It is very interesting that animals with different feeding habits show remarkable difference in activities of ~-glucose transport or hexokinase which may have important roles in glucose metabolism. Relationships between feeding habits and D-giucfXe transport or hexokinase activity should be further studied in many aspects. Moreover, hormonal regulation of the glucose transport system, especially the relationship between insulin and glucose transport activity, and purification or characterization of glucose transport proteins should be studied in many tissues in dogs, cats and cattle.
~-Glucose transport in dogs, cats and cattle REFERENCES
Arai T., Machida Y., Sasaki M. and Oki Y. (1989) Hepatic enzyme activities and plasma insulin concentrations in diabetic herbivorous voles. Vet. Res. Commun. 13, 421-426. Ballard F. J., Filshell 0. H. and Jarrett I. G. (1972) Effects of carbohydrate availability on hpogenesis in sheep. Biothem. J. 126, 193-200. Ballard F. J., Hanson R. W. and Kronfeld D. S. (1%9) Gluconeogenesis and lipogenesis in tissue from ruminant and nomuminant animals. Fed. Proc. 28, 218-231. Be.lsham G. J., Denton R. M. and Tanner M. J. A. (1980) Use of a novel rapid preparation of fat-cell plasma membrane employing Percoll to investigate the effects of insulin and adrenaline on membrane protein phosphorylation within intact fat cells. Biockm. J. 192, 457461. Bergmeyer I-J. H., Gawehn K. and Grassel M. (1974) Hexokinase from yeast. Methoak of Enzymatic Analysis, Vol. 1, pp. 473474. Academic Press, New York. Bradford M. M. (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analyt. Biochem. 72, 248-254. Chastain C. B. (1981) Intensive care of dogs and cats with diabetic ketoacidosis. J. Am. vet. med. ass. 179,972-978. Ciaraldi T. P., Horuk R. and Matthaei S. (1986) Biochemical and functional characterization of the rat liver ghrcase-transport system. Biochem. J. 240, 115-123. Elbrink J. and Bihler I. (1975) Membrane transport: its relation to cellular metabolic rates. Science 188, 1177-l 184. Ferrannini E., Smith J. D., Cobelli C., Toffolo G., Pi10 A. and DeFronzs R. A. (1985) Effect of insulin on the distribution and disposition of ghicose in man. J. clin. Invest. 76, 357-364.
CSP mA,2--E
287
Huggett A. G. and Nixon D. A. (1957) Use of glucose oxidase, peroxidase and odianisidine in determination of blood and urinary ghrcose. Lrmcet 2, 368-370. Kaneko J. J.. Mattheeuws D., Rottiers R. P. and Vermeulen A. (1978) Renal function, insulin secretion, and glucose tolerance in mild streptozotocin diabetes in the dog. Am. J. vet. Res. 39, 807-809. Kasahara M. and Hinkle P. C. (1976) Reconstitution of o-glucose transport catalyzed by a protein fraction from human erythrocytes in sonicated liposomes. Proc. natn. Acad. Sci. U.S.A. 73, 396-400. Kasahara M. and Hinkle P. C. (1977) Reconstitution and purification of the o-glucose ~transporter from human ervthrocvtes. J. biol. Chem. 2!i2. 7384-7390. Ka& M. c and Bergman E. N. (i969) Hepatic and portal metabolism of gh&se, free fatty acids, and ketone bodies in the sheen. Am. J. Phvsiol. 216. 953-960. Mattheeuws b., Rottiers k., Kaneko J. J. and Vermenlen A. (1984) Diabetes melhtus in dogs: relationship of obesity to glucose tolerance and insulin response. Am. J. vet. Res. 45, 98-103. Moise N. S. and Reimers T. J. (1983) Insulin therapy in cats with diabetes mellitus. J. am. vet. med. Ass. 182, 158-164. Mueckler M., Caruso C., Boldwin S. A., Panico M., Blench I., Morris H. R., Allard W. J., Lienhard G. E. and Lodish H. F. (1985) Sequence and structure of a human glucose transporter. Science 229, 941-945. Nelson R. W., Himsel C. A., Feldman E. C. and Bottoms G. D. (1990) Glucose tolerance and insulin response in normal-weight and obese cats. Am. J. vet. Res. 51, 1357-1362. Robinson F. W., Blevins T. L., Suzuki K. and Kono T. (1982) An improved method of reconstitution of adipocyte glucose transport activity. Anafyt. Biochem. 122, 10-19. Wheeler T. J. and Hinkle P. C. (1985) The ghicose transporter of mammalian cells. A. Rev. Physiol. 47, 503-517.
Vol. 102A,
No. 2, pp. 285-287, 1992
0
$5.00 + 0.00 0300-9629/92 1992 PergamonPressLtd
D-GLUCOSE TRANSPORT ACTIVITIES IN ERYTHROCYTES AND HEPATOCYTES OF DOGS, CATS AND CATTLE TOSHIROARAI,* TSUKIMIWASHIZU,T~SHINORISAKO, MINORUSASAKI~ and SHIGEKATSU MOTOYOSHI Department of Veterinary Biochemistry, Nippon Veterinary and Animal Science University, Kyonancho, Musashino, Tokyo 180, Japan; tDevelopment Research Laboratories, Banyu Pharmaceutical Co. Ltd, Manuma, Saitama 360-02, Japan (Received 25 September 1991) Abstract-l. The activities of D-glucose transport and hexokinase were investigated in erythrocytes or hepatocytes of dogs, cats and cattle. 2. The mean o-glucose transport activity in erythrocytes of dogs was 6.0 nmol/min/mg protein, half the value of hepatocytes. 3. The activities of D-ghCOSC transport in erythrocytes and hepatocytes or hepatic hexokinase of cats were about one-third of those of dogs. 4. Cattle with low blood glucose concentrations showed considerably low activities of D-ghCOSe transport and hexokinase, about one-third of those of dogs. diet (Canine p/d, Hill’s Pet Products, KS, U.S.A.), eight mixed-breed cats (four female, four male; 3-5 years old) fed on a commercial diet (Science Diet, Hill’s Pet Products, KS, U.S.A.) and eight lactating cows (3-5 years old) maintained on a diet of grass supplemented with good quality hay and concentrates. Hematological and serum chemistry values of animals examined were all within normal ranges.
INTRODUCTION Circulating serum glucose concentrations are maintained primarily by the balance between uptake of glucose into peripheral tissues and storage by or release from the liver (Ferrannini et nl., 1985). Transport of glucose into the cells is the first step of glucose utilization (Ciaraldi et al., 1986). The transport system for glucose has been extensively studied in erythrocytes, adipocytes and many other cells (Elbrink and Bihler, 1975; Mueckler et al., 1985). It has been reported that all mammalian cells take up glucose by facilitated diffusion catalysed by an integral membrane protein (Kasahara and Hinkle, 1976; Wheeler and Hinkle, 1985). On the other hand, the blood glucose concentrations of herbivorous cattle are low compared with those of dogs as omnivorous animals, and the regulatory mechanism of glucose utilization in cattle is greatly different to that of monogastric animals (Ballard et al., 1969, 1972). It has been reported that some differences between omnivorous dogs and cats as carnivorous animals, are observed in glucose tolerance, insulin response and incidence of glycosuria (Chastain, 1981;MoiseandReimers, 1983;Mattheeuws et al., 1984). It is expected that dogs, cats and cattle have different regulatory mechanisms of glucose utilization adapted to their respective feeding habits. In the present study, glucose transport activities in erythrocytes and hepatocytes or activities of hepatic hexokinase, which catalyses the first step of glycolysis, were measured and investigated in dogs, cats and cattle. MATERIALSAND
METHODS
Animals The following animals were used: eight mixed breed dogs (four female, four male; 4-6 years old) fed on a prescription *To whom all correspondence
should be addressed.
Collection of blood and liver samples Blood was withdrawn from the jugular vein into a heparinized tube. Plasma was recovered by centrifugation and stored at -20°C. The dogs and cats were premeditated with 0.05 mg/kg acepromaxine maleate (Tech America, KS, U.S.A.), and anesthesia was maintained with halothan. Liver samples were taken from the anesthetized animals by laparotomy. Liver samples of cattle were taken by percutaneous needle biopsy. Plasma membrane isolation of erythrocytes and hepatocytes Ghosts were prepared from animal erythrocytes and washed with EDTA and NaCl (Kasahara and Hinkle. 1976). Washed ghosts and removed liver tissues were homogenized in 4 volumes of 10 mM Tris-HCl buffer. DH 7.5. containinn 1 mM EDTA with a Teflon homogeni&.‘Plasma membrane fractions were isolated by the method of Belsham et al. (1980). The collected plasma membrane fraction was washed and finally resuspended in the reaction buffer (0.25 M sucrose, 20 mM Tris-HCl, pH 7.5, 1 mM EDTA) to 1 mg protein/ml, and stored at -80°C until it was assayed. D-Glucose transport activity assay D-Glucose transport activity was measured in the plasma membrane fractions of erythrocytes and hepatocytes prepared by the modification method of Robinson et al. (1982). Briefly, 60 pl of a solution containing 1 mM D- 1-[‘HIglucose (lOO@i/ml, NET-050, DuPont, DE, U.S.A.) and 1 mM L-1-[ “Qlucose (25 &i/ml; NEC-478, DuPont) in the above reaction buffer were added to 60 ~1 of plasma membrane fraction suspended in the same buffer, respectively. The resultant suspension was incubated for 2 min at 37°C and 1 ml of cold stop solution (2 mM HgClJlOmM Tris-HCl, pH 7.5) was added to terminate the reaction. The mixture was immediately filtered by suction with a piece of Millipore GSWP membrane (0.22pm in pore size; Nihon
285
Tosmao AIW et al.
286
Millipore Kogyo K.K., Yonezawa, Japan), which was placed in a filtration apparatus. The test tube containing the reaction mixture was washed once, and the filter membrane was washed twice with 1 ml of the stop solution. The f&r membrane was placed in a scintillation viat, which was then filled with 10 ml of Aquasol- (DuPont), and mechanically shaken for 1 hr. The difference in the amount of D[)H]glucose and L-[Wlglucose collected by the above filtration was assumed to represent the carrier-mediated o-glucose transport activity, which was expressed as nmoles per min per mg protein.
Table 2. Activities of o-glucose transport and total hcxokinase in hepatocytes of dogs, cats and cat&s D-Glucose transport Htxokinase
Dog (5) 11X5*4.0 48.8 f 10.5
#it (St 4.0 f 1.2. 18.7 & 7.9’
Cattle (3) 3.9 f 1.1. 17.5 + 6.7’
Values represent the means & SD (nmol/min/mg protein). Number in parenthesis indicate the number of animals. *Significantly different from the value of the dog (P < 0.01).
Activities of D-glucose transport and hexokinase in hepatocytes of dogs, cats and cattle are shown in Table 2. The D-glUCOSe transport activity in hepatoA part of original homogenate of liver tissue was cencytes of dogs was 11.6 + 4.0 nmol/min/mg protein, trifuged at 15,OOOgfor 30 min at 4°C and then at 100,OOOg which is almost twice of the value in erythrocytes. for 30 min at 4°C. The resulting supernatant was used as Those of cats or cattle were significantly lower hepatic enzyme extract for hexokinase activity assay. Total (P < O.Ol), one-third of the value of dogs. The total hexokinase activity was determined by the method of hexokinase activity in hepatocytes of cats or cattle Bergmeyer et al. ( 1974). The reaction was carried out in the was significantly lower than the value in dogs. micioc&ette, which contained as final concentration, Hexokinase activity assaq
40 mM triethanolamine. OH 7.6. 0.9 mM NADP. 8.0 mM MgCl,, 0.64 mM ATP, 0.6 units/ml of glucose-&phosphate dehydrogenase (Oriental Yeast Co., Tokyo, Japan) and 200mM glucose. The reaction was started by addition of 0.02 ml of enzyme extract, and the absorbance of NADP at 340 nm was measured spectrophotometrically at 23-25°C. The activity is expressed as nmoles of NADPH produced per min per mg protein. Other analysis
Glucose concentrations in whole blood were measured by a glucose oxidase method (Huggett and Nixon, 1957). Plasma insulin #n~ntrations were determined by a micro ELISA sandwich method (Arai et ul., 1989). The protein concentrations in the plasma membrane fractions or enzyme extracts were determined by the method of Bradford (1976) using bovine serum albumin (Wake Pure Chemical Industries, Osaka, Japan) as the standard. Stalistics
Each calculated value was expressed as mean f SD, and the difference between means was analysed by Student’s t-test. RESULTS Blood glucose and plasma insulin ~on~entra~ons and D-&CO%? transport activity in etythrocytes of dogs, cats and cattle are shown in Table 1. The mean
blood glucose concentration of dogs was 100 mg/dl; the mean value for cats was a little lower. The blood glucose concentrations of cattle were significantly lower (P < 0.01) than those of dogs. The plasma insulin concentrations of dogs, cats and cattle were about 20pU/ml. the mean D-glucose transport activity in erythrocytes of dogs was &Onmol/min/mg protein. The activity of cats or cattle was about 2.0 nmol/min/mg protein, which is one-third of the value of dogs. TabIe 1. Blood glucose and plasma insulin ~n~ntratio~ aad ~-glucose transport activities in crythrecytes of dogs, cats and cattle Dog (8) Cat (8) Cattk (8) 60*7* Blood glucoac(mg/dl) lMf&ts 84i9 18*6 22k9 Plasma insulin (rU/ml) 20f8 D-Glucose transport 6fl.4 1,9f0.7* 2.1f0.9’ (nmol/min/mg protein) Values represent the means f SD. Numbers in pamathesis iadicate the number of animals. *Significantlydifferent from the value of the dog (P c 0.01).
DISCUSSION
D-Glucose transport activities in erythrocyte or hepatocytes of dogs were almost the same as values reported previously for humans or rats (Kasahara and Hinkle, 1977; Ciaraldi et al., 1986). The present study showed that D-glucose transport activities in erythrocytes or hepatocytes of cats and cattle were considerably low, about one-third of those of dogs. Cats also showed low activities of hepatic hexokinase. Hyperglycemia is observed more frequently after stress or infusion, with lower concentrations of glucose in cats than in dogs. It has been reported that glucose tolerance of cats is inferior to that of dogs (Kaneko et al., 1978; Nelson et al., 1990). These results may suggest that erythrocytes or liver tissue of cats can utilize less glucose than dogs. Low activities of D-glucose transport or hepatic hexokinase are considered to be correlated with lower ability of glucose utilization observed in cats than in dogs. Although ruminants eat large amounts of carbohydrate consisting mainly of cellulose and hemicellulose, these polymers are degraded in the rumen to yield acetate, propionate and butyrate, and very little glucose is absorbed from the gut (Katz and Bergman, 1969). Glucokinase (type IV hexokinase) with a high Km value for glucose is absent in liver tissue of cattle and glycolytic ability in liver tissue of cattle is very low complared with that of monogastric animals (Ballard et al., 1969). In the present study, total hexokinase activities in liver tissues of cattle were about one third of those of dogs. Low D-@uCOSe transport activities in erythrocytes or hepatocytes are considered to correspond with low metabolic rates of glucose utilization in cattle. It is very interesting that animals with different feeding habits show remarkable difference in activities of ~-glucose transport or hexokinase which may have important roles in glucose metabolism. Relationships between feeding habits and D-giucfXe transport or hexokinase activity should be further studied in many aspects. Moreover, hormonal regulation of the glucose transport system, especially the relationship between insulin and glucose transport activity, and purification or characterization of glucose transport proteins should be studied in many tissues in dogs, cats and cattle.
~-Glucose transport in dogs, cats and cattle REFERENCES
Arai T., Machida Y., Sasaki M. and Oki Y. (1989) Hepatic enzyme activities and plasma insulin concentrations in diabetic herbivorous voles. Vet. Res. Commun. 13, 421-426. Ballard F. J., Filshell 0. H. and Jarrett I. G. (1972) Effects of carbohydrate availability on hpogenesis in sheep. Biothem. J. 126, 193-200. Ballard F. J., Hanson R. W. and Kronfeld D. S. (1%9) Gluconeogenesis and lipogenesis in tissue from ruminant and nomuminant animals. Fed. Proc. 28, 218-231. Be.lsham G. J., Denton R. M. and Tanner M. J. A. (1980) Use of a novel rapid preparation of fat-cell plasma membrane employing Percoll to investigate the effects of insulin and adrenaline on membrane protein phosphorylation within intact fat cells. Biockm. J. 192, 457461. Bergmeyer I-J. H., Gawehn K. and Grassel M. (1974) Hexokinase from yeast. Methoak of Enzymatic Analysis, Vol. 1, pp. 473474. Academic Press, New York. Bradford M. M. (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Analyt. Biochem. 72, 248-254. Chastain C. B. (1981) Intensive care of dogs and cats with diabetic ketoacidosis. J. Am. vet. med. ass. 179,972-978. Ciaraldi T. P., Horuk R. and Matthaei S. (1986) Biochemical and functional characterization of the rat liver ghrcase-transport system. Biochem. J. 240, 115-123. Elbrink J. and Bihler I. (1975) Membrane transport: its relation to cellular metabolic rates. Science 188, 1177-l 184. Ferrannini E., Smith J. D., Cobelli C., Toffolo G., Pi10 A. and DeFronzs R. A. (1985) Effect of insulin on the distribution and disposition of ghicose in man. J. clin. Invest. 76, 357-364.
CSP mA,2--E
287
Huggett A. G. and Nixon D. A. (1957) Use of glucose oxidase, peroxidase and odianisidine in determination of blood and urinary ghrcose. Lrmcet 2, 368-370. Kaneko J. J.. Mattheeuws D., Rottiers R. P. and Vermeulen A. (1978) Renal function, insulin secretion, and glucose tolerance in mild streptozotocin diabetes in the dog. Am. J. vet. Res. 39, 807-809. Kasahara M. and Hinkle P. C. (1976) Reconstitution of o-glucose transport catalyzed by a protein fraction from human erythrocytes in sonicated liposomes. Proc. natn. Acad. Sci. U.S.A. 73, 396-400. Kasahara M. and Hinkle P. C. (1977) Reconstitution and purification of the o-glucose ~transporter from human ervthrocvtes. J. biol. Chem. 2!i2. 7384-7390. Ka& M. c and Bergman E. N. (i969) Hepatic and portal metabolism of gh&se, free fatty acids, and ketone bodies in the sheen. Am. J. Phvsiol. 216. 953-960. Mattheeuws b., Rottiers k., Kaneko J. J. and Vermenlen A. (1984) Diabetes melhtus in dogs: relationship of obesity to glucose tolerance and insulin response. Am. J. vet. Res. 45, 98-103. Moise N. S. and Reimers T. J. (1983) Insulin therapy in cats with diabetes mellitus. J. am. vet. med. Ass. 182, 158-164. Mueckler M., Caruso C., Boldwin S. A., Panico M., Blench I., Morris H. R., Allard W. J., Lienhard G. E. and Lodish H. F. (1985) Sequence and structure of a human glucose transporter. Science 229, 941-945. Nelson R. W., Himsel C. A., Feldman E. C. and Bottoms G. D. (1990) Glucose tolerance and insulin response in normal-weight and obese cats. Am. J. vet. Res. 51, 1357-1362. Robinson F. W., Blevins T. L., Suzuki K. and Kono T. (1982) An improved method of reconstitution of adipocyte glucose transport activity. Anafyt. Biochem. 122, 10-19. Wheeler T. J. and Hinkle P. C. (1985) The ghicose transporter of mammalian cells. A. Rev. Physiol. 47, 503-517.
