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LOWERING PH INCREASES EMBRYONIC SENSITIVITY TO FORMATE IN WHOLE EMBRYO CULTURE
Citation:
Andrews, J., M. Ebron-McCoy, R. Kavlock, AND J. Rogers. LOWERING PH INCREASES EMBRYONIC SENSITIVITY TO FORMATE IN WHOLE EMBRYO CULTURE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/199 (NTIS PB94163789).
Description:
The effects of formate exposure on mammalian embryo development were investigated using the rat whole embryo culture system as a model. ay 9.5 (presomite) rat embryos were explanted and cultured for 48 hours in rotating bottles containing rat serum with 0, 0.2, 0.4, 0.8, 1.2 or 1.6 mg sodium formate/mi culture medium at PH 8.13, 7.75, 7.00, 6.50 or 6.00 to determine if pH of the culture medium can affect the in vitro developmental toxicity of formate. everal parameters of embryonic development decreased in the presence of decreasing pH suggesting that altered pH alone could have a negative impact on embryo development. he 1.6 mg/ml formate exposure level affected protein concentration (PRO), somite number (SN), head length (HD), developmental score (DS), crown rump length (CR) and yolk sac diameter (YS) of embryos at all pH levels. ormate became more toxic with decreasing pH of the culture media. here was an apparent pH dependent increase in embryolethality at the 1.6 mg/mi exposure level and 100% lethality of all embryos at pH 6.00. he 1.2 mg/mi formate concentration affected DS, CR, HL and PRO at the pH 7.75 level whereas 0. 8 mg/mi formate resulted in reduced DS, HL, CR, SN and PRO at pH levels 7.00 and lower. t pH 6.5, embryos not exposed to formate were not significantly different from the other control groups except in reduced CR but at this pH, all exposure levels of formate resulted in microcephaly, reduction in embryonic PRO as well as reduced CR. hese data demonstrate that sensitivity to formate-induced embryo toxicity and dysmorphogenesis in whole embryo culture is increased in the presence of lower pH.