title: Possible mechanism for the frequency-dependent increases in the cardiac contraction in monkey.
abstract: The effects of various interventions on the frequency-dependent increases in the contractility of the papillary muscles of monkeys were investigated. Ouabain (10(-6)M) and KCl-free Krebs-Ringer solution, which are known to inhibit membrane Na+,K+-ATPase (EC 3.6.1.3), abolished the frequency-dependent increases in the contractility of the papillary muscles. Epinephrine (4.5 X 10(8)M) or quinidine (1.3 X 10(-5)M), which are known not to inhibit the membrane Na+,K-ATPase at these concentrations, did not alter the frequency-dependent increases in the contractility. These results indicate that the frequency-dependent increases in the contractility might be mediated through an inhibition of the sarcolemmal Na+,K+-ATPase.
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D004837:Epinephrine / Q000494:pharmacology; D000882:Haplorhini; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D010210:Papillary Muscles / Q000187:drug effects / Q000502:physiology; D011802:Quinidine / Q000494:pharmacology; D013997:Time Factors
chemical_list: D010042:Ouabain; D011802:Quinidine; D004837:Epinephrine