Muscarinic receptor antagonist effects in parotid acini and M1-CHO cells: evidence of G protein involvement.
We have examined the effects of the muscarinic antagonist atropine, on non-receptor-mediated activation of intracellular calcium (Ca2+i) mobilization events. In dispersed rat parotid acini, atropine significantly lowered basal inositol trisphosphate levels and delayed AlF4(-)-stimulated Ca2+i elevation in a dose-dependent manner. In a cell line transfected with the m1 muscarinic receptor (M1-CHO), atropine significantly lowered (approximately 60%) AlF4- stimulated Ca2+i elevation. These aggregate findings suggest that atropine, acting via the muscarinic receptor, decreases the efficacy of G protein-mediated activation of phospholipase C.
Horn
V J
VJ
Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
Baum
B J
BJ
Ambudkar
I S
IS
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism*; D018727:Muscarinic Antagonists; D010053:Ovary; D010306:Parotid Gland; D010738:Type C Phospholipases / Q000378:metabolism
D007295:Inositol Phosphates; D018727:Muscarinic Antagonists; D001285:Atropine; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium