DEPENDENCE OF EXOCRINE SECRETORY CELL PLASMA MEMBRANE Na+-Ca2+-EXCHANGER
CURRENT ON Na+-K+ PUMP FUNCTIONING
V. Manko, O. Larina, M. Klevets
Ivan Franko National University of L'viv,
Hrushevskoho st. 4, L'viv 79005, Ukraine,
e-mail: vvmanko@altavista.com
It is known that activities of sarcolemma Na+-Ca2+ exchanger and Na+-K+ pump are closely interrelated. The aim of our investigation was to study dependence of exocrine secretory cell Na+-Ca2+ exchanger current (INa(Ca)) amplitude on Na+-K+ pump activity under conditions of intracellular perfusion. The INa(Ca) was registered by means of voltage clamp method in response to the membrane hyperpolarization from 20 to 60 mV by rectangular pulses (3.5 sec, 0.1 Hz). We found that ouabain (25 mol/l) did not lead to changes of INa(Ca) amplitude. However, INa(Ca) changes which were caused by a change of intra- and/or extracellular Na+- or K+-concentration greatly depend on presence of ouabain. On the basis of obtained data, we suggest that exocrine secretory cell Na+-Ca2+ exchange depends on Na+-K+ pump functioning as well as cardiomyocites do. In addition, K+ is possibly transported by exchanger with Na+.
Key words: Na+-Ca2+ exchange, Na+ K+ pump, ouabain, exocrine secretory cell.
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