The effect of prolonged treatment with oxyfedrine on intracellular potentials and on other features of cardiac function in rabbits and guinea-pigs.
1. Previous work in acute experiments has shown that the main pharmacological action of oxyfedrine is stimulation of beta-adrenoceptors, yet there have been clinical reports that the drug is beneficial in the treatment of angina pectoris.2. In the present experiments rabbits and guinea-pigs were treated for several weeks with daily i.p. injections of oxyfedrine.3. A daily dosage of 15 mg/kg oxyfedrine had no effect on growth rate for 4 weeks, but thereafter the growth rate of treated animals fell below that of controls.4. The heart weights of the treated animals, expressed as a percentage of body weight, were significantly lower than those of controls.5. Measurement of intracellular potentials in hearts taken from treated rabbits showed that the main effects were a reduction in the maximum rate of depolarization and a prolongation of the plateau of the action potential.6. Guinea-pigs treated for 6 weeks with 15 mg/kg oxyfedrine daily i.p. were protected to some extent from the toxic effect of ouabain infused intravenously.
D000200:Action Potentials / Q000187:drug effects; D000318:Adrenergic beta-Agonists / Q000494:pharmacology* / Q000627:therapeutic use; D000605:Amino Alcohols / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000188:drug therapy; D004562:Electrocardiography; D006128:Growth / Q000187:drug effects; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D006325:Heart Atria / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D010042:Ouabain / Q000037:antagonists & inhibitors; D011427:Propiophenones / Q000494:pharmacology* / Q000627:therapeutic use; D011437:Propylamines / Q000494:pharmacology / Q000627:therapeutic use; D011817:Rabbits; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D013997:Time Factors
D000318:Adrenergic beta-Agonists; D000605:Amino Alcohols; D011427:Propiophenones; D011437:Propylamines; D010042:Ouabain