title: [M-cholinoreceptor-mediated inhibition of Na, K-ATPase activity in the myocardial sarcolemma and intestinal smooth muscles by acetylcholine].
abstract: Acetylcholine (ACH) produced specific inhibition of Na, K-ATP-ase activity in sarcolemmic preparations of the frog heart (K0.5 = 1 microM), dog atria (K0,5 = 5 microM) and ventricles (K0.5 = 1 microM), and dog small intestinal smooth muscles (K0,5 = 0.5 microM). K0.5 is the concentration causing a half-maximal effect. Atropine (10(-7) = 10(-6) M) blocked the inhibitory effect of ACH. The preparations contained a considerable number of 3H-quinuclidinyl benzilate (3H-QNB) binding sites. Treatment of atrial sarcolemma with a mixture of digitonin and sodium cholate resulted in a substantial decrease in the number of 3H-QNB binding sites in the membrane, while Na,K-ATPase lost responsiveness to ACH. In the presence of 10 microM GTP there was a noticeable decrease in sensitivity of the enzyme to ACH. It is assumed that inhibition of Na, K-ATPase activity by acetylcholine is mediated by muscarinic receptor activation with the involvement in this process of GTP-binding proteins.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology*; D011898:Ranidae; D011976:Receptors, Muscarinic / Q000187:drug effects*; D012508:Sarcolemma / Q000187:drug effects / Q000201:enzymology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
chemical_list: D011976:Receptors, Muscarinic; D000254:Sodium-Potassium-Exchanging ATPase; D000109:Acetylcholine
vernacular_title: Oposredovannoe M-kholinoretseptorom ingibirovanie Na, K-ATFaznoĭ aktivnosti sarkolemmy miokarda i gladkikh myshts kishechnika atsetilkholinom.