The effect of prolonged treatment with oxyfedrine on intracellular potentials and on other features of cardiac function in rabbits and guinea‐pigs

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Abstract
1 Previous work in acute experiments has shown that the main pharmacological action of oxyfedrine is stimulation of β-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.