[Properties of large-conductance calcium-activated potassium channel in rat mesenteric arteriole smooth muscle cells].
OBJECTIVE
To investigate the electrophysiological properties of large-conductance calcium-activated potassium channel (BKCa) in mesenteric arteriole smooth muscle cells of rat.


METHODS
Mesenteric arteriolar smooth muscle cells from rats were isolated and inside-out patch clamp technique was used to study BKCa.


RESULTS
The single channel conductance of BKCa recorded was 221+/-6 pS and the reversal potential was -0.12 mV in the presence of high potassium in the bathing and pipette solutions. The open probability (NPo) of the channel was both voltage- and intracellular calcium dependent, whereas the amplitude of the channel was not calcium-dependent. Prolonged closed state could be observed at intracellular calcium concentrations of 1 micromol/L or above, known as calcium-dependent inactivation.


CONCLUSIONS
BKCa in rat mesenteric arterial smooth muscle cells has the properties of large conductance, high potassium selectivity, steep voltage dependence and high calcium sensitivity. The high sensitivity to calcium of BKCa may be related to the compensatory regulation of the smooth muscles in pathophysiological conditions.
Zhao
Gui-ling
GL
Department of Pathophysiology, First Military Medical University, Guangzhou 510515, China. laura@fimmu.com
Pan
Bing-xing
BX
Huang
Xu-liang
XL
Zhao
Ke-sen
KS
D000818:Animals; D005260:Female; D008297:Male; D008564:Membrane Potentials; D008638:Mesenteric Arteries / Q000166:cytology / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D024681:Potassium Channels, Calcium-Activated