Journal of Toxicology and Environmental Health
ISSN: 0098-4108 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/uteh19
Biotransformation, sex hormones, and toxicity of two volatile anesthetics in mice H. F. Cascorbi , R. M. Gesinski & M. K. Komar To cite this article: H. F. Cascorbi , R. M. Gesinski & M. K. Komar (1976) Biotransformation, sex hormones, and toxicity of two volatile anesthetics in mice, Journal of Toxicology and Environmental Health, 1:5, 839-842, DOI: 10.1080/15287397609529383 To link to this article: http://dx.doi.org/10.1080/15287397609529383
Published online: 20 Oct 2009.
Submit your article to this journal
Article views: 3
View related articles
Citing articles: 3 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 Cambridge]
Date: 06 November 2015, At: 17:53
BIOTRANSFORMATION, SEX HORMONES, AND TOXICITY OF TWO VOLATILE ANESTHETICS IN MICE H. F. Cascorbi Department of Anesthesiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio R. M. Gesinski, M. K. Komar
Downloaded by [University of Cambridge] at 17:53 06 November 2015
Department of Biological Sciences, Kent State University, Kent, Ohio
Male and female DBA 1J mice recovered from 1 hr of anesthesia with chloroform or fluroxene apparently unharmed. However, many of the animals died within 24-48 hr after anesthesia. Pretreatment with phenobarbital increased, while pretreatment with a small dose of carbon tetrachloride decreased, this toxicity. Relatively more males than females died. Pretreatment with estradiol in males and testosterone in females reversed this ratio. We conclude that the murine toxicity of chloroform and fluroxene is dependent on biotransformation by hepatic microsomal enzymes and that the testosterone enhances postanesthetic toxicity of these agents.
INTRODUCTION Biotransformation of drugs generally leads to less active, less toxic compounds. However, volatile anesthetics that exert their central nervous system depression by physical interaction can be converted to toxic metabolites in animals and humans (Cascorbi, 1973). We have shown previously that trifluoroethylvinylether, or fluroxene (Fluoromar), is biotransformed to the toxic metabolite trifluoroethanol in mice, dogs, and humans (Blake et al., 1967; Cascorbi, 1974). This biotransformation was enhanced or decreased by pretreatment with stimulators or depressors of hepatic drug metabolism (Cascorbi and Singh-Amaranath, 1972). Testing 13 now used volatile anesthetics we found four of them to produce postanesthetic biotransformation-dependent toxicity, among them fluroxene and chloroform (Cascorbi et al., 1974). Sex differences of drug metabolism have been demonstrated in some mouse strains (Westfall et al., 1964). Therefore we investigated the postanesthetic toxicity of fluroxene and chloroform in male and female mice.
Requests for reprints should be sent to H. F. Cascorbi, Department of Anesthesiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106.
839 Journal of Toxicology and Environmental Health, 1:839-842, 1976 Copyright © 1976 by Hemisphere Publishing Corporation
840
H. F. CASCORBI ET AL.
Downloaded by [University of Cambridge] at 17:53 06 November 2015
METHODS DBA 1J mice of either sex were bred and raised in the animal facilities of the Department of Biological Sciences at Kent State University. The animals were kept in an air-conditioned room with a reasonable diurnal cycle and fed Purina mouse chow and water ad libitum. Care was taken to avoid unscheduled exposures to xenobiotics. The animals were used when they had reached a body weight of 20-30 g. Pretreatments consisted of one of the following: (1) no drugs; (2) sodium phenobarbital USP, 0.25% in the drinking water for 5 days prior to anesthesia; (3) carbon tetrachloride (Baker reagent), 20% in Wesson oil, 0.2 ml sc/mouse 24 hr prior to anesthesia; (4) testosterone (Lilly) 5 mg in oil sc/female mouse for 12 days prior to anesthesia; (5) estradiol (Schering) 100 /xg in oil sc/male mouse for'12 days prior to anesthesia. The animals were anesthetized in groups of about 15 in desiccators with inlet and outlet for anesthetic gases. A high flow of air through a suitable vaporizer filled with chloroform or fluroxene was used. Previous experience had shown that PO2 and PCO2 in the desiccators remained normal under those conditions (Cascorbi and Singh-Amaranath, 1972). Anesthetic concentrations were kept between 4 and 4.5% for fluroxene and 1 and 2% for chloroform. All animals walked within 5 min after the anesthetic was discontinued. The animals were observed for postanesthetic death for at least 48 hr. Where indicated, the results were evaluated by the x square test.
TABLE 1. Death 48 hr after Anesthesia with Chloroform (CHL) or Fluroxene (FL)
Pretreatment"
Anesthetic
Minutes of anesthesia
N
Sex
None None None None
CHL CHL FL FL CHL CHL CHL CHL FL FL FL FL
60 60 60 60 15 15 60 60 15 15 60 60
32 33 84 95 21 21 21 23 26 21 15 15
M F M F M F M F M F M F
P P C C P P C C
Percent dead 47 0
64 0 100 38 0 0 88 38 0 0
°The animals were either not pretreated or pretreated with phenobarbital (P) or carbon tetrachloride (C).
TOXICITY OF CHLOROFORM AND FLUROXENE
841
TABLE 2. Death 48 hr after Pretreatment with Estradiol in Males and Testosterone in Females and 1 hr of Anesthesia with Chloroform (CHL) or Fluroxene (FL) Anesthetic
N
Sex
Percent dead
CHL CHL
29 26
M F
6.9 26.9°
FL FL
35 28
M F
0 43
a
p < 0.05.
Downloaded by [University of Cambridge] at 17:53 06 November 2015
RESULTS Table 1 shows that 1 hr of anesthesia with chloroform killed about one-half the males; with fluroxene two-thirds the males were killed within 48 hr after anesthesia. Furthermore, pretreatment with phenobarbital increased postanesthetic lethality of both agents markedly: fifteen minutes of anesthesia was now enough to kill most or all males and one-third the females. Pretreatment with carbon tetrachloride abolished postanesthetic toxicity in males. Pretreatment with the "opposite" sex hormone reversed the susceptibility of the animals: now more females than males died after anesthesia with either anesthetic (Table 2). DISCUSSION These studies demonstrate that there is a sex difference in favor of females in the postanesthetic mortality after anesthesia with fluroxene or with chloroform. DBA 1J mice were used because they are inbred and genetically very uniform. This toxicity is dependent on biotransformation since phenobarbital, an enzyme inducer, increased the toxicity of both anesthetics in both sexes, while enzyme suppression by a small dose of carbon tetrachloride (Glende, 1972) abolished toxicity in the males. An explanation for the observed sex difference can be sought in the action of testosterone on drug-metabolizing enzymes. P-450 activity in male rats is higher than in females (Quinn et al., 1958), and treatment with sex active steroids alters this ratio. We postulate that our doses of testosterone increased microsomal activity in female mice and led to the production of more toxic metabolites. Estradiol, on the other hand, suppressed testosterone production in the males and led to a decrease in postanesthetic toxicity. Measurements of metabolic rates of fluroxene ancl chloroform in male and female mice would confirm or disprove this explanation of our results.
842
H. F. CASCORBI ETAL.
REFERENCES
Downloaded by [University of Cambridge] at 17:53 06 November 2015
Blake, D. A., Rozman, R. S., Cascorbi, H. F., et al. 1967. Anesthesia LXXIV: Biotransformation of fluroxene. I. Metabolism in mice and dogs in vivo. Biochem. Pharmacol. 16:1237-1248. Cascorbi, H. F. 1973. Biotransformation of drugs used in anesthesia. Anesthesiology 39:115-125. Cascorbi, H. F. 1974. Biotransformation of fluroxene. Int. Anesthesiol. Clinics 12:107-110. Cascorbi, H. F. and Singh-Amaranath, A. V. 1972. Fluroxene toxicity in mice. Anesthesiology 37:480-482. Cascorbi, H. F., Kalhan, S. B. and Dauchot, P. J. 1974. Toxicitat des Divinylathers und anderer Inhalationsnarcotica an Mäusen. Anaesthesist 23:469-471. Glende, E. A., Jr. 1972. Carbon tetrachloride induced protection against carbon tetrachloride toxicity: The role of the liver microsomal enzymes on drug metabolizing systems. Biochem. Pharmacol. 21:1697-1702. Quinn, P. G., Axelrod, Y. and Brodie, B. B. 1958. Species, strain and sex differences in metabolism of hexobarbitone, amidopyrine, antipyrine and aniline. Biochem. Pharmacol. 1:152-159. Westfall, A., Boulos, B. M., Shields, J. L., et al. 1964. Sex differences in pentobarbital sensitivity in mice. Proc. Soc. Exp. Biol. Med. 115:509-510. Received August 8, 1975 Accepted November 4, 1975
ISSN: 0098-4108 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/uteh19
Biotransformation, sex hormones, and toxicity of two volatile anesthetics in mice H. F. Cascorbi , R. M. Gesinski & M. K. Komar To cite this article: H. F. Cascorbi , R. M. Gesinski & M. K. Komar (1976) Biotransformation, sex hormones, and toxicity of two volatile anesthetics in mice, Journal of Toxicology and Environmental Health, 1:5, 839-842, DOI: 10.1080/15287397609529383 To link to this article: http://dx.doi.org/10.1080/15287397609529383
Published online: 20 Oct 2009.
Submit your article to this journal
Article views: 3
View related articles
Citing articles: 3 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 Cambridge]
Date: 06 November 2015, At: 17:53
BIOTRANSFORMATION, SEX HORMONES, AND TOXICITY OF TWO VOLATILE ANESTHETICS IN MICE H. F. Cascorbi Department of Anesthesiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio R. M. Gesinski, M. K. Komar
Downloaded by [University of Cambridge] at 17:53 06 November 2015
Department of Biological Sciences, Kent State University, Kent, Ohio
Male and female DBA 1J mice recovered from 1 hr of anesthesia with chloroform or fluroxene apparently unharmed. However, many of the animals died within 24-48 hr after anesthesia. Pretreatment with phenobarbital increased, while pretreatment with a small dose of carbon tetrachloride decreased, this toxicity. Relatively more males than females died. Pretreatment with estradiol in males and testosterone in females reversed this ratio. We conclude that the murine toxicity of chloroform and fluroxene is dependent on biotransformation by hepatic microsomal enzymes and that the testosterone enhances postanesthetic toxicity of these agents.
INTRODUCTION Biotransformation of drugs generally leads to less active, less toxic compounds. However, volatile anesthetics that exert their central nervous system depression by physical interaction can be converted to toxic metabolites in animals and humans (Cascorbi, 1973). We have shown previously that trifluoroethylvinylether, or fluroxene (Fluoromar), is biotransformed to the toxic metabolite trifluoroethanol in mice, dogs, and humans (Blake et al., 1967; Cascorbi, 1974). This biotransformation was enhanced or decreased by pretreatment with stimulators or depressors of hepatic drug metabolism (Cascorbi and Singh-Amaranath, 1972). Testing 13 now used volatile anesthetics we found four of them to produce postanesthetic biotransformation-dependent toxicity, among them fluroxene and chloroform (Cascorbi et al., 1974). Sex differences of drug metabolism have been demonstrated in some mouse strains (Westfall et al., 1964). Therefore we investigated the postanesthetic toxicity of fluroxene and chloroform in male and female mice.
Requests for reprints should be sent to H. F. Cascorbi, Department of Anesthesiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106.
839 Journal of Toxicology and Environmental Health, 1:839-842, 1976 Copyright © 1976 by Hemisphere Publishing Corporation
840
H. F. CASCORBI ET AL.
Downloaded by [University of Cambridge] at 17:53 06 November 2015
METHODS DBA 1J mice of either sex were bred and raised in the animal facilities of the Department of Biological Sciences at Kent State University. The animals were kept in an air-conditioned room with a reasonable diurnal cycle and fed Purina mouse chow and water ad libitum. Care was taken to avoid unscheduled exposures to xenobiotics. The animals were used when they had reached a body weight of 20-30 g. Pretreatments consisted of one of the following: (1) no drugs; (2) sodium phenobarbital USP, 0.25% in the drinking water for 5 days prior to anesthesia; (3) carbon tetrachloride (Baker reagent), 20% in Wesson oil, 0.2 ml sc/mouse 24 hr prior to anesthesia; (4) testosterone (Lilly) 5 mg in oil sc/female mouse for 12 days prior to anesthesia; (5) estradiol (Schering) 100 /xg in oil sc/male mouse for'12 days prior to anesthesia. The animals were anesthetized in groups of about 15 in desiccators with inlet and outlet for anesthetic gases. A high flow of air through a suitable vaporizer filled with chloroform or fluroxene was used. Previous experience had shown that PO2 and PCO2 in the desiccators remained normal under those conditions (Cascorbi and Singh-Amaranath, 1972). Anesthetic concentrations were kept between 4 and 4.5% for fluroxene and 1 and 2% for chloroform. All animals walked within 5 min after the anesthetic was discontinued. The animals were observed for postanesthetic death for at least 48 hr. Where indicated, the results were evaluated by the x square test.
TABLE 1. Death 48 hr after Anesthesia with Chloroform (CHL) or Fluroxene (FL)
Pretreatment"
Anesthetic
Minutes of anesthesia
N
Sex
None None None None
CHL CHL FL FL CHL CHL CHL CHL FL FL FL FL
60 60 60 60 15 15 60 60 15 15 60 60
32 33 84 95 21 21 21 23 26 21 15 15
M F M F M F M F M F M F
P P C C P P C C
Percent dead 47 0
64 0 100 38 0 0 88 38 0 0
°The animals were either not pretreated or pretreated with phenobarbital (P) or carbon tetrachloride (C).
TOXICITY OF CHLOROFORM AND FLUROXENE
841
TABLE 2. Death 48 hr after Pretreatment with Estradiol in Males and Testosterone in Females and 1 hr of Anesthesia with Chloroform (CHL) or Fluroxene (FL) Anesthetic
N
Sex
Percent dead
CHL CHL
29 26
M F
6.9 26.9°
FL FL
35 28
M F
0 43
a
p < 0.05.
Downloaded by [University of Cambridge] at 17:53 06 November 2015
RESULTS Table 1 shows that 1 hr of anesthesia with chloroform killed about one-half the males; with fluroxene two-thirds the males were killed within 48 hr after anesthesia. Furthermore, pretreatment with phenobarbital increased postanesthetic lethality of both agents markedly: fifteen minutes of anesthesia was now enough to kill most or all males and one-third the females. Pretreatment with carbon tetrachloride abolished postanesthetic toxicity in males. Pretreatment with the "opposite" sex hormone reversed the susceptibility of the animals: now more females than males died after anesthesia with either anesthetic (Table 2). DISCUSSION These studies demonstrate that there is a sex difference in favor of females in the postanesthetic mortality after anesthesia with fluroxene or with chloroform. DBA 1J mice were used because they are inbred and genetically very uniform. This toxicity is dependent on biotransformation since phenobarbital, an enzyme inducer, increased the toxicity of both anesthetics in both sexes, while enzyme suppression by a small dose of carbon tetrachloride (Glende, 1972) abolished toxicity in the males. An explanation for the observed sex difference can be sought in the action of testosterone on drug-metabolizing enzymes. P-450 activity in male rats is higher than in females (Quinn et al., 1958), and treatment with sex active steroids alters this ratio. We postulate that our doses of testosterone increased microsomal activity in female mice and led to the production of more toxic metabolites. Estradiol, on the other hand, suppressed testosterone production in the males and led to a decrease in postanesthetic toxicity. Measurements of metabolic rates of fluroxene ancl chloroform in male and female mice would confirm or disprove this explanation of our results.
842
H. F. CASCORBI ETAL.
REFERENCES
Downloaded by [University of Cambridge] at 17:53 06 November 2015
Blake, D. A., Rozman, R. S., Cascorbi, H. F., et al. 1967. Anesthesia LXXIV: Biotransformation of fluroxene. I. Metabolism in mice and dogs in vivo. Biochem. Pharmacol. 16:1237-1248. Cascorbi, H. F. 1973. Biotransformation of drugs used in anesthesia. Anesthesiology 39:115-125. Cascorbi, H. F. 1974. Biotransformation of fluroxene. Int. Anesthesiol. Clinics 12:107-110. Cascorbi, H. F. and Singh-Amaranath, A. V. 1972. Fluroxene toxicity in mice. Anesthesiology 37:480-482. Cascorbi, H. F., Kalhan, S. B. and Dauchot, P. J. 1974. Toxicitat des Divinylathers und anderer Inhalationsnarcotica an Mäusen. Anaesthesist 23:469-471. Glende, E. A., Jr. 1972. Carbon tetrachloride induced protection against carbon tetrachloride toxicity: The role of the liver microsomal enzymes on drug metabolizing systems. Biochem. Pharmacol. 21:1697-1702. Quinn, P. G., Axelrod, Y. and Brodie, B. B. 1958. Species, strain and sex differences in metabolism of hexobarbitone, amidopyrine, antipyrine and aniline. Biochem. Pharmacol. 1:152-159. Westfall, A., Boulos, B. M., Shields, J. L., et al. 1964. Sex differences in pentobarbital sensitivity in mice. Proc. Soc. Exp. Biol. Med. 115:509-510. Received August 8, 1975 Accepted November 4, 1975
