Ca 2+ -activated Cl - channels in Ehrlich ascites tumor cells are distinct from mCLCA1, 2 and3

Autor: Jana Papassotiriou, Jan Eggermont, Guillaume Droogmans, Bernd Nilius
Rok vydání: 2001
Předmět:
Zdroj: Pfl�gers Archiv European Journal of Physiology. 442:273-279
ISSN: 1432-2013
0031-6768
DOI: 10.1007/s004240100526
Popis: Using the whole-cell patch-clamp technique, we have studied the electrophysiological and pharmacological properties of the Ca(2+)-activated Cl- current present in Ehrlich cells. The currents activated slowly upon depolarization, deactivated upon hyperpolarization, and showed strong outward rectification. An increase in [Ca2+]i activated the current with an EC50 of 165.2 nM. Extracellular application of niflumic acid (100 microM) rapidly blocked the current in a voltage-dependent manner whereas sulfhydryl-modifying agents such as dithiothreitol (DTT, 1-2 mM) and N-ethylmaleimide (NEM, 100 microM) had no effect on Ca(2+)-activated currents in Ehrlich cells. Members of the recently discovered CLCA gene family are the only molecular candidates for Ca(2+)-activated Cl- channels cloned so far. Using RT-PCR we demonstrated that the appearance of a Ca(2+)-activated Cl- current in Ehrlich cells is not associated with the expression of the murine members of the CLCA family (mCLCA1-mCLCA3). Correspondingly, the kinetic and pharmacological properties of the Ca(2+)-activated current in Ehrlich cells differ from those of CLCA-associated currents, which are time independent and DTT sensitive. Thus, phenotypic differences in combination with RT-PCR data point to the existence of different molecular species for Ca(2+)-activated Cl- channels.
Databáze: OpenAIRE
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