Hyposmotic membrane stretch potentiated muscarinic receptor agonist-induced depolarization of membrane potential in guinea-pig gastric myocytes.
OBJECTIVE
To investigate the relationship between hyposmotic membrane stretch and muscarinic receptor agonist-induced depolarization of membrane potential in antral gastric circular myocytes of guinea-pig.


METHODS
Using whole cell patch-clamp technique recorded membrane potential and current in single gastric myocytes isolated by collagenase.


RESULTS
Hyposmotic membrane stretch hyperpolarized membrane potential from -60.0mV+/-1.0mV to -67.9mV+/-1.0mV. TEA (10 mmol/L), a nonselective potassium channel blocker significantly inhibited hyposmotic membrane stretch-induced hyperpolarization. After KCl in the pipette and NaCl in the external solution were replaced by CsCl to block the potassium current, hyposmotic membrane stretch depolarized the membrane potential from -60.0 mV+/-1.0mV to -44.8 mV+/-2.3mV (P<0.05), and atropine (1 micromol/L) inhibited the depolarization of the membrane potential. Muscarinic receptor agonist Carbachol depolarized membrane potential from -60.0mV+/-1.0mV to -50.3 mV+/-0.3mV (P<0.05) and hyposmotic membrane stretch potentiated the depolarization. Carbachol induced muscarinic current (I( cch )) was greatly increased by hyposmotic membrane stretch.


CONCLUSIONS
Hyposmotic membrane stretch potentiated muscarinic receptor agonist-induced depolarization of membrane potential, which is related to hyposmotic membrane stretch-induced increase of muscarinic current.
Li
Lin
L
Department of Physioloy, Yanbian University College of Medicine, Juzi 121, Yanji 133000, Jilin Province, China. wenxiexu@ybu.edu.cn
Jin
Nan-Ge
NG
Piao
Lin
L
Hong
Ming-Yu
MY
Jin
Zheng-Yuan
ZY
Li
Ying
Y
Xu
Wen-Xie
WX
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009470:Muscle Spindles / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009997:Osmotic Pressure; D013270:Stomach / Q000166:cytology / Q000502:physiology
D018721:Muscarinic Agonists; D002217:Carbachol