Involvement of the phospholipase C beta1 pathway in desensitization of the carbachol-activated nonselective cationic current in murine gastric myocytes.
In murine gastrointestinal myocytes muscarinic stimulation activates nonselective cation channels via a G-protein and Ca2+-dependent pathway. We recorded inward cationic currents following application of carbachol (ICCh) to murine gastric myocytes held at -60 mV, using the whole-cell patch-clamp method. The properties of the inward cationic currents were similar to those of the nonselective cation channels activated by muscarinic stimulation in other gastrointestinal smooth muscle cells. CCh-induced ICCh and spontaneous decay of ICCh (desensitization of ICCh) occurred. Unlike the situation in guinea pig gastric myocytes, desensitization was not affected by varying [EGTA]i. Pretreatment with the PLC inhibitor (U73122) blocked the activation of ICCh, and desensitization of ICCh was attenuated in PLC beta1 knock-out mice. These results suggest that the desensitization of ICCh in murine gastric myocytes is not due to a pathway dependent on intracellular Ca2+ but to the PLC beta1 pathway.
Kim
Byung Joo
BJ
Department of Physiology and Biophysics, Seoul National University College of Medicine, Seoul 110-799, Korea.
So
Insuk
I
Kim
Ki Whan
KW
D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D027682:Cation Transport Proteins; D002412:Cations / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D051379:Mice; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D054799:Phospholipase C beta; D013270:Stomach / Q000166:cytology; D010738:Type C Phospholipases / Q000378:metabolism*
D027682:Cation Transport Proteins; D002412:Cations; D007473:Ion Channels; D007527:Isoenzymes; D004533:Egtazic Acid; D002217:Carbachol; D010738:Type C Phospholipases; D054799:Phospholipase C beta; C518034:Plcb1 protein, mouse