Published online Aug 15, 2002. doi: 10.3748/wjg.v8.i4.724
Revised: April 22, 2002
Accepted: April 27, 2002
Published online: August 15, 2002
AIM: 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 -60.0 mV ± 1.0 mV to -67.9 mV ± 1.0 mV. 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 ± 1.0 mV to -44.8 mV ± 2.3 mV (P < 0.05), and atropine (1 μmol/L) inhibited the depolarization of the membrane potential. Muscarinic receptor agonist Carbachol depolarized membrane potential from -60.0 mV ± 1.0 mV to -50.3 mV ± 0.3 mV (P < 0.05) and hyposmotic membrane stretch potentiated the depolarization. Carbachol induced muscarinic current (Icch) was greatly increased by hyposmotic membrane stretch.
CONCLUSION: Hyposmotic membrane stretch potentiated muscarinic receptor agonist-induced depolarization of membrane potential, which is related to hyposmotic membrane stretch-induced increase of muscarinic current.