| Autor: |
Wada, Akihiko, Urabe, Masanobu, Yuhi, Tomoaki, Yamamoto, Ryuichi, Yanagita, Toshihiko, Niina, Hiromi, Kobayashi, Hideyuki |
| Zdroj: |
Naunyn-Schmiedeberg's Archives of Pharmacology; 1995, Vol. 352 Issue 5, p545-549, 5p |
| Abstrakt: |
In cultured bovine adrenal chromaffln cells, charybdotoxin and iberiotoxin (inhibitors of the large-conductance Ca-activated K channel) as well as apamin (an inhibitor of the small-conductance Ca-activated K channel), at 1-100 nM, suppressed carbachol-induced Rb efflux, augmented carbachol-induced Ca influx via voltage-dependent Ca channels and catecholamine secretion and had no effect on carbachol-induced Na influx via nicotinic receptors, a prerequisite for Ca channel activation by carbachol. Ca influx caused by high K (a direct activation of voltage-dependent Ca channels) was also enhanced by these K channel inhibitors, with the concentration-response curves being similar to those for carbachol-induced Ca influx. Dendrotoxin and mast cell degranulating peptide (inhibitors of voltage-dependent K channels), on the other hand, did not alter carbachol-induced Rb efflux or Ca influx. These results suggest that the stimulation of nicotinic receptors eventually opens large- and small-conductance Ca-activated K channels, and that the blockade of these Ca-activated K channels results in gating of voltage-dependent Ca channels and thereby augments catecholamine secretion from bovine adrenal chromaffln cells. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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