title: Effects of quinidine, lidocaine and encainide on guinea pig myocardial Na(+)-K(+)-ATPase activity.
abstract: The effects of three Class I antiarrhythmic agents, quinidine (Class 1A), lidocaine (Class 1B) and encainide (Class 1C) on the Mg2(+)-dependent, Na+/K+ activated adenosine triphosphatase were compared with those of ouabain in microsomal preparations of the guinea pig heart. Lidocaine and quinidine inhibited the ATP-hydrolysis by the Na(+)-K(+)-ATPase in a concentration-dependent fashion similar to that of ouabain. The concentrations for half maximal inhibition of the enzyme activity were 4.1 +/- 0.7 mM for lidocaine and 0.46 +/- 0.12 mM for quinidine. Encainide exhibited stimulatory tendency at pharmacological concentrations, enhancing the enzyme activity by 2.5% at 1.0 microM and 25% at 1.0 mM. These results show that the Class I antiarrhythmic drugs may influence the Na(+)-K(+)-ATPase activity in different ways.
authors.affiliation: Department of Pharmacology, King Saud University, Riyadh, Saudi Arabia.
authors.forename: A A
authors.initials: AA
authors.lastname: Almotrefi
authors.forename: N
authors.initials: N
authors.lastname: Dzimiri
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000813:Anilides / Q000494:pharmacology*; D000818:Animals; D016700:Encainide; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology*; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D011802:Quinidine / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D000813:Anilides; D000255:Adenosine Triphosphate; D008012:Lidocaine; D000254:Sodium-Potassium-Exchanging ATPase; D011802:Quinidine; D016700:Encainide