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Effects of pH on the genesis of membrane potential changes at fertilization in the egg of the frog Rana cameranoi

The apparent change in the egg membrane potential at fertilization gives rise to fertilization potential (FP). FP is the initial, transient electrical block to polyspermy as shown in most species especially those exhibiting external fertilization, and it protects the egg from a second sperm entry until the permanent, mechanical block is set up. | Turk J Biol 24 (2000) 725–736 © TÜBİTAK Effects of pH on the Genesis of Membrane Potential Changes at Fertilization in the Egg of the Frog Rana cameranoi* Şeref ERDOĞAN, Gülay LOĞOĞLU, Kerem T. ÖZGÜNEN, T. ÖZGÜNEN Çukurova University Faculty of Medicine Department of Physiology 01330 Balcalı, Adana-TURKEY Received: 03.09.1999 Abstract: The apparent change in the egg membrane potential at fertilization gives rise to fertilization potential (FP). FP is the initial, transient electrical block to polyspermy as shown in most species especially those exhibiting external fertilization, and it protects the egg from a second sperm entry until the permanent, mechanical block is set up. Polyspermy is lethal in most species, and for a successful fertilization resting membrane potential (RMP) and FP of the egg have to be held in optimum ranges. Shifts in environmental pH may interfere with a successful fertilization by affecting these bioelectrical potentials. In the present study, we investigated how pH alterations affected the RMP and FP parameters of the egg in the frog, Rana cameranoi. Egg membrane potentials were recorded by the conventional microelectrode technique. RMP and FP parameters were evaluated. Ten percent Ringer solution (pH=7.80) was used for the control group. Acidic (Acd) and alkaline (Alk) experimental groups were kept in the Ringer solutions at pH 6.50 and 9.00, respectively. RMP was found to be significantly more negative in the Acd group (p0.05). Pik FP, Alk grubunda anlamlı olarak daha pozitif değerlere ulaşırken Asit grubunda anlamlı olarak daha az pozitif değerlerde kayıt edildi. FP süresi, Alk grubunda anlamlı olarak daha uzun iken Asit grubunda süre kısaldı ancak bu kısalma istatistiksel olarak anlamlı değildi. Fertilize yumurtanın zar potansiyeli Asit grubunda Alk grubuna göre anlamlı olarak daha hiperpolarize iken kontrole göre anlamlı farklılık göstermedi. Bu sonuçlar çerçevesinde orta düzeyde pH kaymaları FP parametrelerine anlamlı .