title: Influence of lorcainide on microsomal Na+, K(+)-ATPase in guinea-pig isolated heart preparations.
abstract: 1. The effects of lorcainide on the myocardial Mg2(+)-dependent, Na+ and K(+)-activated adenosine triphosphatase (Na+, K(+)-ATPase) were compared in guinea-pig heart preparations with those of ouabain, a specific inhibitor of the enzyme activity. 2. Both ouabain and lorcainide inhibited the microsomal Na+, K(+)-ATPase activity in a concentration-dependent fashion. Their inhibitory effective ranges were 0.05-100 microM and 0.15-125 microM, respectively, and the concentrations for half maximal inhibition (IC50 values) were 2.1 +/- 0.3 and 33.5 +/- 7.3 microM, respectively. 3. In a second series of experiments, the combined effects of the two drugs on the enzyme activity were studied. In these experiments, lorcainide produced a concentration-dependent potentiation of the inhibitory effects of ouabain on Na+, K(+)-ATPase activity. 4. The present study demonstrates that lorcainide is a potent inhibitor of myocardial Na+, K(+)-ATPase.
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: D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D044482:Benzeneacetamides; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009206:Myocardium / Q000201:enzymology; D010042:Ouabain / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
chemical_list: D000889:Anti-Arrhythmia Agents; D044482:Benzeneacetamides; D010880:Piperidines; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; C015970:lorcainide