Acetazolamide induces a unique and characteristic limb deformity in the offspring of pregnant rodents. The teratogenic mechanism of action is thought to be inhibition of carbonic anhydrase. One after effect of carbonic anhydrase inhibition is raised arterial and tissue carbon dioxide content and we have now demonstrated that maternal carbon dioxide inhalation leads to the same unique forelimb deformity substantiating the idea that carbonic anhydrase inhibition is the mechanism of acetazolamide teratogenesis. This application describes experiments which will attempt to uncover the mechanism by which C02 perturbs development. We hypothesize that C02 lowers intracellular pH (pHi) which subsequently leads to decreased proliferative rate thereby leading to the limb reduction deformity. We will measure pHi in the developing limb bud after teratogen treatment and attempt to correlate any changes with teratologic outcome and proliferative rate. The ability of limb bud cells to respond to internal pH changes will be documented and manipulation of this process will be correlated with teratologic outcome. We believe that reducing the intracellular pH of embryonic cells may be a general mechanism of teratogenesis and intend to study one human teratogen, alcohol, which could conceivably act through this mechanism.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD019260-02
Application #
3316499
Study Section
Toxicology Study Section (TOX)
Project Start
1986-04-01
Project End
1989-03-31
Budget Start
1987-04-01
Budget End
1988-03-31
Support Year
2
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Cincinnati Children's Hospital Medical Center
Department
Type
DUNS #
071284913
City
Cincinnati
State
OH
Country
United States
Zip Code
45229
Collins, M D; Walling, K M; Resnick, E et al. (1991) The effect of administration time on malformations induced by three anticonvulsant agents in C57BL/6J mice with emphasis on forelimb ectrodactyly. Teratology 44:617-27
Srivastava, M; Collins, M D; Scott Jr, W J et al. (1991) Transplacental distribution of weak acids in mice: accumulation in compartments of high pH. Teratology 43:325-9
Collins, M D; Fradkin, R; Scott Jr, W J (1990) Induction of postaxial forelimb ectrodactyly with anticonvulsant agents in A/J mice. Teratology 41:61-70
Zimmerman, E F; Scott Jr, W J; Collins, M D (1990) Ethanol-induced limb defects in mice: effect of strain and Ro15-4513. Teratology 41:453-62
Scott, W J; Duggan, C A; Schreiner, C M et al. (1990) Reduction of embryonic intracellular pH: a potential mechanism of acetazolamide-induced limb malformations. Toxicol Appl Pharmacol 103:238-54
Collins, M D; Duggan, C A; Schreiner, C M et al. (1989) Decreasing pH of rat embryos and fluids estimated by transplacental distribution of DMO. Am J Physiol 257:R542-9