Role of actin microfilament in hyposmotic membrane stretch 2 induced increase in muscarinic current of guinea 2 pig gastric myocytes

To investigate the relationship between cytoskeleton and hyposmotic membrane stretch2induced increase in mus2 carinic current , the role of actin microfilament in hyposmotic membrane stretch2induced increase in muscarinic current was studied with the whole2cell patch clamp technique in guinea2pig gastric myocytes. In this study , the muscarinic current was induced by carbachol ( 50 μmol/ L ) or GTPγS ( 015 mmol/ L ) . The results showed that hyposmotic superfusate ( 202 mOsmol/ L) increased carbachol2induced current ( ICCh) by 145 ±27 % and increased GTPγS2induced current by 183 ±30 % ; but in the presence of cytochalasin2B (Cyt2B , 20μmol/ L) , an actin cytoskeleton disruptor , hyposmotic membrane stretch increased ICCh by 70 ±6 %. However , hyposmotic membrane stretch induced increase in ICCh was potentiated to 545 ±81 % by phalloidin (20μmol/ L) , an actin microfilament stabilizer. The results demonstrated that hyposmotic membrane stretch increased the muscarinic currents induced by carbachol or GTPγS and that the actin microfilament is involved in the process in guinea2pig gastric myocytes.