Effects of H^+-K^+ ATPase Inhibitors (Omeprazole and Lansoprazole) on Fertilization-Induced Bioelectrical Potential Changes in the Egg of the Frog, Rana cameranoi


Abstract: Fertilization triggers Ca^{2+} increase and alkalization in the eggs of some species such as the frog. Ooplasmic Ca^{2+} increase triggers fertilization potential (FP), and alkalization can have a permissive effect in Ca^{2+} increase. It can be expected that pH regulation in the egg can affect both ooplasmic Ca^{2+} levels and the events triggered by increasing Ca^{2+}. The evidence of the possibility of H^+-K^+ ATPase in different tissues in recent studies prompted us to wonder about the probability of the existence of this pump in the egg. Therefore, we decided to investigate the presence of H^+-K^+ ATPase by bioelectrical potential recordings in frog eggs. Thus, frog eggs were inseminated while the resting membrane potential (RMP) in the solution containing different concentrations (0.3, 0.6, 0.9 and 1.2 mM) of pump inhibitors (omeprazole and lansoprazole) was recorded. Evidence of H^+-K^+ ATPase was sought from the effects of these pump inhibitors on FP variables. While omeprazole had a significant effect on RMP and FP variables at a 1.2 mM concentration alone, lansoprazole had significant effects at concentrations higher than 0.6 mM in the frog eggs. It was determined that the effects of the 2 inhibitors were similar. In conclusion, H^+-K^+ ATPase may be present in frog eggs due to the similar effects of both pump inhibitors on the potential change triggered by fertilization. Thus, this pump might have a function in alkalization triggered by fertilization in the frog egg.

Keywords: Frog egg, H^+-K^+ ATPase, bioelectrical potentials, omeprazole, lansoprazole

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