Calcium-sensitive potassium current in isolated canine coronary smooth muscle cells

Canadian Journal of Physiology and Pharmacology
N BuljubasicZ J Bosnjak

Abstract

This study characterizes K+ current in canine coronary artery and investigates its role in regulation of vascular smooth muscle tone during the resting and activated state. Isolated rings and whole-cell K+ current as well as single K+ channels were studied. Tetraethylammonium (< 3 mM) did not increase the resting tension in isolated rings; however, 0.3 mM tetraethylammonium increased tension in vessels that were precontracted by elevated [K+]o or 5-hydroxytryptamine (5-HT). The whole-cell K+ current showed voltage and Ca2+ dependency and sensitivity to tetraethylammonium (31 +/- 7, 72 +/- 2, and 83 +/- 4% depression by 1, 10, and 30 mM tetraethylammonium, respectively). A large-conductance (100 pS) K+ channel was identified in cell-attached patches with open-time distribution fitted with two exponentials. Calcium ionophore A23187 (10 microM) increased the probability of opening, mean open time, and amplitude of this channel in cell-attached patches, suggesting Ca2+ dependency. A23187 shifted the plot of unitary current as a function of pipette potential to the right, suggesting A23187-induced cell hyperpolarization. In inside-out patches, increase in cytoplasmic-side [Ca2+] from 10(-7) to 10(-6) M increased both the frequency o...Continue Reading

Citations

Sep 28, 2000·Canadian Journal of Physiology and Pharmacology·L WuR Wang

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