Journal of Toxicology and Environmental Health
ISSN: 0098-4108 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/uteh19
Cadmium treatment and lead‐induced suppression of splenic erythropoiesis G. R. Hogan To cite this article: G. R. Hogan (1992) Cadmium treatment and lead‐induced suppression of splenic erythropoiesis, Journal of Toxicology and Environmental Health, 35:1, 1-6, DOI: 10.1080/15287399209531588 To link to this article: http://dx.doi.org/10.1080/15287399209531588
Published online: 15 Oct 2009.
Submit your article to this journal
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Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=uteh20 Download by: [University of Florida]
Date: 09 November 2015, At: 20:02
CADMIUM TREATMENT AND LEAD-INDUCED SUPPRESSION OF SPLENIC ERYTHROPOIESIS G. R. Hogan
Journal of Toxicology and Environmental Health 1992.35:1-6.
College of Science and Technology, St. Cloud State University, St. Cloud, Minnesota
Young adult female mice were injected with lead acetate (d 0). Following injection, determinations were made of the percentages of radioactive iron (59Fe) uptake into the hemoglobin of erythrocytes produced by spleen. Control 59Fe uptake percentage vacillated between 4.2 and 5.5 within the 7-d period of observation. On d 4 following lead treatment, splenic percentages were dramatically reduced below those of the saline-injected controls; by d 6 the splenic 59Fe uptake of lead-treated mice was comparable to that of controls. For rodents injected with cadmium chloride on d 0, the 59 Fe uptake values showed a statistically significant elevation by d 2, which was extended beyond that of the controls' d 4 value. For those animals receiving both lead and cadmium (d 0), the uptake percentages paralleled those of the controls throughout the 7-d period of observation. These data suggest that the inhibitory effect of lead on erythropoiesis of the spleen is blocked by a concurrent cadmium treatment. Results are interpreted in regard to a possible vulnerable target and competition for the target by lead and cadmium.
INTRODUCTION The process of erythrocyte production and release, erythropoiesis, represents a series of events including striking biochemical activity associated with hemoglobin synthesis. It has been proposed that the synthesis of hemoglobin is a major regulatory factor that controls erythropoiesis. The overall process of erythropoiesis and, thus, hemoglobin synthesis, is subject to a number of endogenous factors (Levander, 1977) as well as exogenous ones. Recent studies have revealed that environmental materials are focal among the external agents. These agents include trace substances, one of which is lead. Lead has been widely studied (Zeller, 1971) and is known to have a devastating effect on a broad spectrum of biologic systems. These effects span those from the total organism level of organization (Port et al., 1974) through the molecular level (Tomokuni and Ogata, 1975). It has been reported that lead affects the erythropoietic process by rendering less active an enzyme focal in hemoglobin synthesis, that is, delta-aminolevulinic acid dehyRequests for reprints should be sent to G. Richard Hogan, College of Science and Technology, St. Cloud State University, St. Cloud, MN 56301-4498. 1 Journal of Toxicology and Environmental Health, 35:1-6, 1992 Copyright © 1992 by Hemisphere Publishing Corporation
2
G. R. HOGAN
dratase (Morse et al., 1972). Conversely, cadmium treatment has been shown to increase the extent of hemoglobin synthesis as measured by the uptake of radioactive iron into hemoglobin-synthesizing erythrocytes (Hogan, 1987). The studies reported here were undertaken to test the effects of separate treatments of lead and cadmium and a combined treatment on erythropoiesis of the mouse spleen. The spleen is well suited for such studies because it is a compact tissue and relatively simple to prepare for determination of its erythropoietic activity.
Journal of Toxicology and Environmental Health 1992.35:1-6.
MATERIALS AND METHODS
Female mice of the ICR strain were used throughout these investigations. Unless otherwise designated, 15 mice comprised each subgroup of the control and experimental groups. Lead acetate was prepared on the day of the intraperitoneal (ip) injection (d 0) according to the method of Kostial et al. (1974). The lead acetate treatment was 100 mg/kg; this has been reported to be the most efficient level in regard to maximum erythropoietic effectiveness with minimum mortality (Hogan, 1987). A standard volume of 0.2 ml was delivered because animal weight variations were relatively small among subgroups. Average weight of mice was 31.7 g with a range of 29.6-33.3 g. Aqueous cadmium chloride was administered by ip injection on d 0 at a level of 2.0 mg/kg body weight. Both cadmium and lead compounds were obtained from Pfaltz and Bauer (Stamford, CT). Control animals were injected (ip) with a 0.2ml volume of isotonic saline, which represented the volumes of the lead acetate and cadmium chloride injectate volume. At scheduled intervals following lead acetate and/or cadmium chloride injection(s), mice were euthanized by cervical dislocation. Using heparin as the anticoagulant, spleen were dissected and prepared for subsequent determination of their radioactive iron content. Radioactive iron (59Fe) was administered 24 h before tissue harvest. The activity injected was 0.5 ¿iCi 59Fe (citrate, aqueous, New England Nuclear, Boston, MA) in a 0.1-ml volume. A deep-well scintillation counter was used to determine the radioactivity of the spleen, which was expressed as the percentage uptake of the total 59Fe detected in 100 mg of spleen. Appropriate corrections were made for significant counting parameters. The day of a specific 59Fe uptake percentage represented the incorporation or retention during the 24-h interval between 59Fe administration and excision of the spleen, that is, 24-h uptake percentages. Immediately after removal of the spleen, the organ was rinsed in chilled isotonic saline, gently blotted dry, and weighed to the nearest milligram. Liver and skeletal muscle were also dissected and served as control tissues. Following rinsing and weighing, the 59Fe contents of liver and muscle
Cd EFFECTS O N Pb-SUPPRESSED ERYTHROPOIESIS
3
were determined and expressed in the percentage 59Fe uptake per 100 mg tissue weight.
Journal of Toxicology and Environmental Health 1992.35:1-6.
RESULTS AND DISCUSSION
Figure 1 illustrates the depressor effect of lead acetate on radioiron uptake by splenic tissue. Control percentages vacillated between 4.5 and 5.0. On d 3 following lead, however, the uptake percentages were approximately 69% of the control values, 3.75 and 5.0, respectively. A more striking inhibition was observed on d 4 when the lead acetatetreated 59Fe percentages were about 38% of the control value. Recovery appears to have begun by d 5, reaching full recovery by d 6, at which time the experimental and control 59Fe percentages do not statistically differ (p < .001). This inhibitory effect of lead on splenic erythropoiesis has been reported previously in regard to the magnitude of radioiron uptake suppression and thé time course of the inhibitory effect and the recovery phase (Hogan, 1977). In contrast to the preceding response, injection of cadmium chloride on d 0 stimulated erythropoiesis of spleen (Fig. 2). The accelecatory effect began on d 2 and continued through d 4. The cadmium-treated mice showed 29, 60, and 44% increases in their 59Fe uptake percentages over those of the control values on d 2, 3, and 4, respectively. The p
Ml LU _l
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DAYS FOLLOWING INJECTION FIGURE 1. Twenty-four-hour percentage of 59Fe detected in splenic tissue of mice injected with lead acetate (100 mg/kg) on d 0 and the 59Fe uptake percentage of mice treated with ¡sotonic saline (0.2 ml) on d 0. Vertical line of a point represents the standard error of the mean.
G. R. HOGAN
Journal of Toxicology and Environmental Health 1992.35:1-6.
4
values for the level of significance at these times were all less than .001. It will be noted that the peak response following cadmium was detected on d 3, although the d 2 and 4 percentages did not differ significantly. In Figure 1 the maximum depression induced by lead is shown to have occurred between 24 and 48 h later. Cadmium has been reported to produce a similar effect and temporal response for peripheral erythrocytes (Hogan, 1987). Treatment with both lead acetate and cadmium appeared to have no effect on radioiron uptake percentages compared to control percentages. Figure 3 illustrates these erythropoietic responses. The experimental (lead and cadmium) and control percentages ranged between 4.1 and 5.1%, respectively. Thus the inhibitory effect of lead on splenic erythropoiesis and the stimulatory one of cadmium appeared to "cancel" each other. There were no significant differences observed between the mean 59Fe percentages for skeletal muscle obtained from lead-, lead and cadmium-, or cadmium-treated mice compared to control muscle percentages. This was the case for hepatic tissue as well. In this system, and at the dosages of lead and cadmium that were tested, the splenic radioiron uptake percentage values may suggest that the treatments are influencing the same or similar targets. It has been re-
DAYS FOLLOWING INJECTION FIGURE 2. Twenty-four-hour percentage of 59Fe detected in splenic tissue of mice injected with cadmium chloride (2.0 mg/kg) on d 0 and the 59Fe uptake percentage of mice treated with isotonic saline (0.2 ml) on d 2. Vertical line of a point represents the standard error of the mean.
5
Cd EFFECTS O N Pb-SUPPRESSED ERYTHROPOIESIS
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Journal of Toxicology and Environmental Health 1992.35:1-6.
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DAYS FOLLOWING INJECTION FIGURE 3. Percentage of 59Fe uptake into splenic tissues of mice treated with lead acetate (100 mg/kg) and cadmium chloride (2.0 mg/kg) on d 0 and sacrificed at daily intervals postinjection. Closed circles represent 59Fe uptake values of spleen (100 mg/kg) excised from mice receiving 0.2 ml isotonic saline on d 0.
ported that lead's inhibitory action on erythropoiesis is due to inhibitory or a reduced activity level of the enzyme, delta-aminolevulinic acid dehydratase (Morse et al., 1972). It is tempting to postulate that, because cadmium treatment was effective in blocking the suppressor of lead, cadmium may exert its stimulatory effect on erythropoiesis of spleen by increasing the level of activity of this key enzyme in the process of hemoglobin formation. Others have shown that cadmium affects the level of delta-aminolevulinic acid dehydratase of peripheral blood cells of the mouse (Davis and Avram, 1978). The data presented in Figure 2 are consistent with these findings; that is, if cadmium increased the amount of enzyme participating in formation of hemoglobin by erythrocytes by the spleen, more hemoglobin synthesis would occur, more 59Fe would be utilized in the process, and the uptake percentages would be elevated above the noncadmium-treated or control levels. Whether or not cadmium and lead compete for the same vulnerable target(s), it is clear from the data presented here that the splenic erythropoietic response of mice treated with cadmium is stimulatory; with lead it is inhibitory; and with both materials there is no observable effect, suggesting a cancellation of the materials' effectiveness.
G. R. HOGAN
6
Journal of Toxicology and Environmental Health 1992.35:1-6.
REFERENCES Davis, J. R., and Avram, M. J. 1978. A comparison of the stimulatory effects of cadmium and zinc on normal and lead-inhibited human erythrocytic delta-aminolevulinic acid dehydratase activity in vitro. Toxico!. Appl. Pharmacol. 44:181-190. Hogan, G. R. 1977. Single lead acetate insult, testosterone therapy, and erythropoiesis in mice. J. Toxicol. Environ. Health 3:377-388. Hogan, G. R. 1987. Cadmium effects on erythrocyte delta-aminolevulinic acid dehydratase levels and radioiron incorporation percentages. Heavy Metals Environ. 2:83-85. Kostial, K., Maljkovic, T., and Jugo, S. 1974. Lead acetate toxicity in rats in relation to age and sex. Arch. Toxikol. 31:265-269 Levander, I. A. 1977. Nutritional factors in relation to heavy metal toxicants. Fed. Proc. 36:1683-1687. Morse, B. S., Germans, G. J. and Givliani, D. G. 1972. Abnormal erythroid maturation following acute lead toxicity in mice. Blood 39:713-720. Port, C. D., Baxter, D. W. and Richter, W. R. 1974.The Mongolian gerbil as a model for lead toxicity: 1. Studies of acute poisoning. Am. J. Pathol. 76:79-94. Tomokuni, K., and Ogata, M. 1975. The effect of exposing men and animals to lead on the pH activity curves of hepatic and erythrocyte delta-aminolevulinate dehydratase. Ind. Health. 13:31-36. Zeller, H. D. 1971. Proc. Workshop on Toxic Metals in Water, pp. 29-37. N.C. Department of Natural Economic Resources and Water Resources, Res. Int. report no. 57. Received February 25, 1991 Accepted July 24, 1991
ISSN: 0098-4108 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/uteh19
Cadmium treatment and lead‐induced suppression of splenic erythropoiesis G. R. Hogan To cite this article: G. R. Hogan (1992) Cadmium treatment and lead‐induced suppression of splenic erythropoiesis, Journal of Toxicology and Environmental Health, 35:1, 1-6, DOI: 10.1080/15287399209531588 To link to this article: http://dx.doi.org/10.1080/15287399209531588
Published online: 15 Oct 2009.
Submit your article to this journal
View related articles
Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=uteh20 Download by: [University of Florida]
Date: 09 November 2015, At: 20:02
CADMIUM TREATMENT AND LEAD-INDUCED SUPPRESSION OF SPLENIC ERYTHROPOIESIS G. R. Hogan
Journal of Toxicology and Environmental Health 1992.35:1-6.
College of Science and Technology, St. Cloud State University, St. Cloud, Minnesota
Young adult female mice were injected with lead acetate (d 0). Following injection, determinations were made of the percentages of radioactive iron (59Fe) uptake into the hemoglobin of erythrocytes produced by spleen. Control 59Fe uptake percentage vacillated between 4.2 and 5.5 within the 7-d period of observation. On d 4 following lead treatment, splenic percentages were dramatically reduced below those of the saline-injected controls; by d 6 the splenic 59Fe uptake of lead-treated mice was comparable to that of controls. For rodents injected with cadmium chloride on d 0, the 59 Fe uptake values showed a statistically significant elevation by d 2, which was extended beyond that of the controls' d 4 value. For those animals receiving both lead and cadmium (d 0), the uptake percentages paralleled those of the controls throughout the 7-d period of observation. These data suggest that the inhibitory effect of lead on erythropoiesis of the spleen is blocked by a concurrent cadmium treatment. Results are interpreted in regard to a possible vulnerable target and competition for the target by lead and cadmium.
INTRODUCTION The process of erythrocyte production and release, erythropoiesis, represents a series of events including striking biochemical activity associated with hemoglobin synthesis. It has been proposed that the synthesis of hemoglobin is a major regulatory factor that controls erythropoiesis. The overall process of erythropoiesis and, thus, hemoglobin synthesis, is subject to a number of endogenous factors (Levander, 1977) as well as exogenous ones. Recent studies have revealed that environmental materials are focal among the external agents. These agents include trace substances, one of which is lead. Lead has been widely studied (Zeller, 1971) and is known to have a devastating effect on a broad spectrum of biologic systems. These effects span those from the total organism level of organization (Port et al., 1974) through the molecular level (Tomokuni and Ogata, 1975). It has been reported that lead affects the erythropoietic process by rendering less active an enzyme focal in hemoglobin synthesis, that is, delta-aminolevulinic acid dehyRequests for reprints should be sent to G. Richard Hogan, College of Science and Technology, St. Cloud State University, St. Cloud, MN 56301-4498. 1 Journal of Toxicology and Environmental Health, 35:1-6, 1992 Copyright © 1992 by Hemisphere Publishing Corporation
2
G. R. HOGAN
dratase (Morse et al., 1972). Conversely, cadmium treatment has been shown to increase the extent of hemoglobin synthesis as measured by the uptake of radioactive iron into hemoglobin-synthesizing erythrocytes (Hogan, 1987). The studies reported here were undertaken to test the effects of separate treatments of lead and cadmium and a combined treatment on erythropoiesis of the mouse spleen. The spleen is well suited for such studies because it is a compact tissue and relatively simple to prepare for determination of its erythropoietic activity.
Journal of Toxicology and Environmental Health 1992.35:1-6.
MATERIALS AND METHODS
Female mice of the ICR strain were used throughout these investigations. Unless otherwise designated, 15 mice comprised each subgroup of the control and experimental groups. Lead acetate was prepared on the day of the intraperitoneal (ip) injection (d 0) according to the method of Kostial et al. (1974). The lead acetate treatment was 100 mg/kg; this has been reported to be the most efficient level in regard to maximum erythropoietic effectiveness with minimum mortality (Hogan, 1987). A standard volume of 0.2 ml was delivered because animal weight variations were relatively small among subgroups. Average weight of mice was 31.7 g with a range of 29.6-33.3 g. Aqueous cadmium chloride was administered by ip injection on d 0 at a level of 2.0 mg/kg body weight. Both cadmium and lead compounds were obtained from Pfaltz and Bauer (Stamford, CT). Control animals were injected (ip) with a 0.2ml volume of isotonic saline, which represented the volumes of the lead acetate and cadmium chloride injectate volume. At scheduled intervals following lead acetate and/or cadmium chloride injection(s), mice were euthanized by cervical dislocation. Using heparin as the anticoagulant, spleen were dissected and prepared for subsequent determination of their radioactive iron content. Radioactive iron (59Fe) was administered 24 h before tissue harvest. The activity injected was 0.5 ¿iCi 59Fe (citrate, aqueous, New England Nuclear, Boston, MA) in a 0.1-ml volume. A deep-well scintillation counter was used to determine the radioactivity of the spleen, which was expressed as the percentage uptake of the total 59Fe detected in 100 mg of spleen. Appropriate corrections were made for significant counting parameters. The day of a specific 59Fe uptake percentage represented the incorporation or retention during the 24-h interval between 59Fe administration and excision of the spleen, that is, 24-h uptake percentages. Immediately after removal of the spleen, the organ was rinsed in chilled isotonic saline, gently blotted dry, and weighed to the nearest milligram. Liver and skeletal muscle were also dissected and served as control tissues. Following rinsing and weighing, the 59Fe contents of liver and muscle
Cd EFFECTS O N Pb-SUPPRESSED ERYTHROPOIESIS
3
were determined and expressed in the percentage 59Fe uptake per 100 mg tissue weight.
Journal of Toxicology and Environmental Health 1992.35:1-6.
RESULTS AND DISCUSSION
Figure 1 illustrates the depressor effect of lead acetate on radioiron uptake by splenic tissue. Control percentages vacillated between 4.5 and 5.0. On d 3 following lead, however, the uptake percentages were approximately 69% of the control values, 3.75 and 5.0, respectively. A more striking inhibition was observed on d 4 when the lead acetatetreated 59Fe percentages were about 38% of the control value. Recovery appears to have begun by d 5, reaching full recovery by d 6, at which time the experimental and control 59Fe percentages do not statistically differ (p < .001). This inhibitory effect of lead on splenic erythropoiesis has been reported previously in regard to the magnitude of radioiron uptake suppression and thé time course of the inhibitory effect and the recovery phase (Hogan, 1977). In contrast to the preceding response, injection of cadmium chloride on d 0 stimulated erythropoiesis of spleen (Fig. 2). The accelecatory effect began on d 2 and continued through d 4. The cadmium-treated mice showed 29, 60, and 44% increases in their 59Fe uptake percentages over those of the control values on d 2, 3, and 4, respectively. The p
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I
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LU
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DAYS FOLLOWING INJECTION FIGURE 1. Twenty-four-hour percentage of 59Fe detected in splenic tissue of mice injected with lead acetate (100 mg/kg) on d 0 and the 59Fe uptake percentage of mice treated with ¡sotonic saline (0.2 ml) on d 0. Vertical line of a point represents the standard error of the mean.
G. R. HOGAN
Journal of Toxicology and Environmental Health 1992.35:1-6.
4
values for the level of significance at these times were all less than .001. It will be noted that the peak response following cadmium was detected on d 3, although the d 2 and 4 percentages did not differ significantly. In Figure 1 the maximum depression induced by lead is shown to have occurred between 24 and 48 h later. Cadmium has been reported to produce a similar effect and temporal response for peripheral erythrocytes (Hogan, 1987). Treatment with both lead acetate and cadmium appeared to have no effect on radioiron uptake percentages compared to control percentages. Figure 3 illustrates these erythropoietic responses. The experimental (lead and cadmium) and control percentages ranged between 4.1 and 5.1%, respectively. Thus the inhibitory effect of lead on splenic erythropoiesis and the stimulatory one of cadmium appeared to "cancel" each other. There were no significant differences observed between the mean 59Fe percentages for skeletal muscle obtained from lead-, lead and cadmium-, or cadmium-treated mice compared to control muscle percentages. This was the case for hepatic tissue as well. In this system, and at the dosages of lead and cadmium that were tested, the splenic radioiron uptake percentage values may suggest that the treatments are influencing the same or similar targets. It has been re-
DAYS FOLLOWING INJECTION FIGURE 2. Twenty-four-hour percentage of 59Fe detected in splenic tissue of mice injected with cadmium chloride (2.0 mg/kg) on d 0 and the 59Fe uptake percentage of mice treated with isotonic saline (0.2 ml) on d 2. Vertical line of a point represents the standard error of the mean.
5
Cd EFFECTS O N Pb-SUPPRESSED ERYTHROPOIESIS
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Journal of Toxicology and Environmental Health 1992.35:1-6.
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CONTROL
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4
6
DAYS FOLLOWING INJECTION FIGURE 3. Percentage of 59Fe uptake into splenic tissues of mice treated with lead acetate (100 mg/kg) and cadmium chloride (2.0 mg/kg) on d 0 and sacrificed at daily intervals postinjection. Closed circles represent 59Fe uptake values of spleen (100 mg/kg) excised from mice receiving 0.2 ml isotonic saline on d 0.
ported that lead's inhibitory action on erythropoiesis is due to inhibitory or a reduced activity level of the enzyme, delta-aminolevulinic acid dehydratase (Morse et al., 1972). It is tempting to postulate that, because cadmium treatment was effective in blocking the suppressor of lead, cadmium may exert its stimulatory effect on erythropoiesis of spleen by increasing the level of activity of this key enzyme in the process of hemoglobin formation. Others have shown that cadmium affects the level of delta-aminolevulinic acid dehydratase of peripheral blood cells of the mouse (Davis and Avram, 1978). The data presented in Figure 2 are consistent with these findings; that is, if cadmium increased the amount of enzyme participating in formation of hemoglobin by erythrocytes by the spleen, more hemoglobin synthesis would occur, more 59Fe would be utilized in the process, and the uptake percentages would be elevated above the noncadmium-treated or control levels. Whether or not cadmium and lead compete for the same vulnerable target(s), it is clear from the data presented here that the splenic erythropoietic response of mice treated with cadmium is stimulatory; with lead it is inhibitory; and with both materials there is no observable effect, suggesting a cancellation of the materials' effectiveness.
G. R. HOGAN
6
Journal of Toxicology and Environmental Health 1992.35:1-6.
REFERENCES Davis, J. R., and Avram, M. J. 1978. A comparison of the stimulatory effects of cadmium and zinc on normal and lead-inhibited human erythrocytic delta-aminolevulinic acid dehydratase activity in vitro. Toxico!. Appl. Pharmacol. 44:181-190. Hogan, G. R. 1977. Single lead acetate insult, testosterone therapy, and erythropoiesis in mice. J. Toxicol. Environ. Health 3:377-388. Hogan, G. R. 1987. Cadmium effects on erythrocyte delta-aminolevulinic acid dehydratase levels and radioiron incorporation percentages. Heavy Metals Environ. 2:83-85. Kostial, K., Maljkovic, T., and Jugo, S. 1974. Lead acetate toxicity in rats in relation to age and sex. Arch. Toxikol. 31:265-269 Levander, I. A. 1977. Nutritional factors in relation to heavy metal toxicants. Fed. Proc. 36:1683-1687. Morse, B. S., Germans, G. J. and Givliani, D. G. 1972. Abnormal erythroid maturation following acute lead toxicity in mice. Blood 39:713-720. Port, C. D., Baxter, D. W. and Richter, W. R. 1974.The Mongolian gerbil as a model for lead toxicity: 1. Studies of acute poisoning. Am. J. Pathol. 76:79-94. Tomokuni, K., and Ogata, M. 1975. The effect of exposing men and animals to lead on the pH activity curves of hepatic and erythrocyte delta-aminolevulinate dehydratase. Ind. Health. 13:31-36. Zeller, H. D. 1971. Proc. Workshop on Toxic Metals in Water, pp. 29-37. N.C. Department of Natural Economic Resources and Water Resources, Res. Int. report no. 57. Received February 25, 1991 Accepted July 24, 1991
