Effects of different kinds of stretch on voltage-dependent calcium current in antrial circular smooth muscle cells of the guinea-pig.
In order to elucidate the effect of membrane stretch on ionic currents, we employed the whole-cell patch-clamp technique to investigate the effects of different kinds of stretch on voltage-dependent calcium currents in antrial circular smooth muscle cells of the guinea-pig. The membrane stretch induced by superfusing the smooth muscle cells with hyposmotic bath solution enhanced voltage-operated calcium current and activated inward holding current. The increase in calcium current occurred within 1 minute of superfusion and the sustained inward holding current was slowly activated after prominent cell swelling. Voltage-dependent calcium currents (Ica) were significantly increased by membrane stretch which was induced by cell swelling and cell inflation, but was not affected by direct longitudinal stretch (110  130%) using two electrodes. The results suggest that the cell membrane stretch can increase voltage-dependent calcium channel activity and the effect of stretch on calcium channels was related to the membrane tension and/or the direction of membrane stretch.
Xu
W X
WX
Department of Physiology, College of Medicine, Yanbian University, Yanji 133000, China. wenxiexu@ybu.edu.cn
Li
Y
Y
Wu
L R
LR
Li
Z L
ZL
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011706:Pyloric Antrum / Q000502:physiology; D013270:Stomach / Q000502:physiology*
D015220:Calcium Channels; D002118:Calcium