caa a22 4500 477074146 CHVBK 20180405111435.0 cr unu---uuuuu 170330e19960701xx s 000 0 eng 10.1007/BF02262777 doi (NATIONALLICENCE)springer-10.1007/BF02262777 Dependence of sodium-calcium exchange current through the membrane of salivary gland cells of Chironomus on pH of the extracellular solution [Elektronische Daten] [M. Klevets, V. Man'ko, N. Fedirko] The dependence of sodium-calcium exchange current (I Na(Ca)) through the membrane of isolated secretory cells ofChironomus larva on pH of the extracellular solution was studied with the voltage-clamp technique with intracellular perfusion.I Na(Ca) evoked by hyperpolarization of the membrane from −20 to −60 mV was recorded within physiological values of Na+ and Ca2+ gradients. It was established that acidification of extracellular solution from pH 7.2 to 4.0 gradually decreased the amplitude ofI Na(Ca) with pK' — 3.72. In all cases at pH 3.0 an outward current of considerable amplitude emerged in response to membrane hyperpolarization. The reversal of the current occurred at pH around 3.25. A decrease inI Na(Ca) was due to protonation of acid ionogenic groups (quite possibly, of the residues of aspartic or glutamic amino acids), which had been involved in binding of cations. Alkalization of extracellular solution from pH 7.2 to 10.0 produced a gradual increase in theI Na(Ca) amplitude; pK' was in the pH range between 9 and 10. The increase inI Na(Ca) in alkaline medium was probably due to the appearance of negatively charged cations at binding sites, which could be carried by deprotonated thiosulfate groups of cysteine residues. This was indicated by the possibility of initial decrease inI Na(Ca) under the action of Hg2+ ions. Plenum Publishing Corporation, 1997 Klevets M. Franko State University, L'vov, Ukraine aut Man'ko V. Franko State University, L'vov, Ukraine aut Fedirko N. Franko State University, L'vov, Ukraine aut Neurophysiology Kluwer Academic Publishers-Plenum Publishers 28/4-5(1996-07-01), 151-154 0090-2977 28:4-5<151 1996 28 11062 https://doi.org/10.1007/BF02262777 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02262777 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Klevets M. Franko State University, L'vov, Ukraine aut NATIONALLICENCE 700 1- Man'ko V. Franko State University, L'vov, Ukraine aut NATIONALLICENCE 700 1- Fedirko N. Franko State University, L'vov, Ukraine aut NATIONALLICENCE 773 0- Neurophysiology Kluwer Academic Publishers-Plenum Publishers 28/4-5(1996-07-01), 151-154 0090-2977 28:4-5<151 1996 28 11062 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer