Evidence for the Coupling of Muscarinic M3 Receptor to Cyclic AMP Formation and Poly-Phosphatidylinositol Turnover in Rat Salivary Glands

大白鼠唾腺上M3香蕈亞型受體與腺核苷酸環化酶活化及多磷脂醯肌醇轉換作用兩者偶合現象之研究

魏健吾(Jiann-Wu Wei) ； 葉世榮(Shih-Rung Yeh) ； 王明城(Edward K. Wang)

《The Chinese Journal of Physiology》 34卷3期 (1991/09) Pp. 303-315

摘要

Wei,J.W.,S.R.Yeh,and E.K.Wang, Evidence for the coupling of muscarinic M3 receptor to cyclic AMP formation and poly-phosphatidylinositol turnover in rat salivaryglands. Chinese J.Physiol.34(3):303-315,1991.The biochemical events which arecoupled to the subtypes of muscarinic cholinergic receptors in rat salivary glands were studied. The subtype property of this receptor system was characterized by the use of (superscript 3)H-QNB binding to glandular membrane homogenates. The Kd and Bmax values of this binding were found to be 0.2nM and 210 fmole/mg protein respectively. In the drug-displacement study on the (superscript 3)H-QNB binding the following potency order was obtained(based on the IC50 values calculated from each individual dose-response curve):Atropine＞4-DAMP＞HHSiD＞Pirenzepine＞AF-DX 116. This order is a typical M3 muscarinic subtype, according to the recent consensus. Carbachol(0.1mM)caused a 4.4-fold increased in IP3 productionover the basal level, when tissue fragments were prelabeled with (superscript 3)H-inositol. The abovementioned cholinergic antagonists could block this event in a similar potency order. Carbachol (0.1mM)did not have a significant effect on the basal level of cAMP formation of these tissue homogenates. On the other hand, it had a 33% reduction of isoproterenol (10 μM)-enhancing cAMP formation. The reduction effect of carbachol on cAMP formation could also be blocked by the above mentioned cholinergic antagonists in a similar order. Our results indicated that rat salivary glands have M3 muscarinic receptors and theactivation of these receptors causes changes in both phosphatidylinositol turnover and cAMP formation.

並列摘要

Wei,J.W.,S.R.Yeh,and E.K.Wang, Evidence for the coupling of muscarinic M3 receptor to cyclic AMP formation and poly-phosphatidylinositol turnover in rat salivaryglands. Chinese J.Physiol.34(3):303-315,1991.The biochemical events which arecoupled to the subtypes of muscarinic cholinergic receptors in rat salivary glands were studied. The subtype property of this receptor system was characterized by the use of (superscript 3)H-QNB binding to glandular membrane homogenates. The Kd and Bmax values of this binding were found to be 0.2nM and 210 fmole/mg protein respectively. In the drug-displacement study on the (superscript 3)H-QNB binding the following potency order was obtained(based on the IC50 values calculated from each individual dose-response curve):Atropine＞4-DAMP＞HHSiD＞Pirenzepine＞AF-DX 116. This order is a typical M3 muscarinic subtype, according to the recent consensus. Carbachol(0.1mM)caused a 4.4-fold increased in IP3 productionover the basal level, when tissue fragments were prelabeled with (superscript 3)H-inositol. The abovementioned cholinergic antagonists could block this event in a similar potency order. Carbachol (0.1mM)did not have a significant effect on the basal level of cAMP formation of these tissue homogenates. On the other hand, it had a 33% reduction of isoproterenol (10 μM)-enhancing cAMP formation. The reduction effect of carbachol on cAMP formation could also be blocked by the above mentioned cholinergic antagonists in a similar order. Our results indicated that rat salivary glands have M3 muscarinic receptors and theactivation of these receptors causes changes in both phosphatidylinositol turnover and cAMP formation.

並列關鍵字

Muscarinic receptor dubtype ； phosphoinositide turnover ； rat salivary glands ； (superscript 3)H-QNB binding ； cAMP formation