The cardiovascular effect of chloroquine in anaesthetized dogs

Abstract

Dogs were anaesthetized with sodium pentobarbitone and the effects, on the cardiovascular system, of graded doses of chloroquine were investigated.Intravenous injection of chloroquine from 2 to 4 mg kg⁻¹ produced significant reductions in cardiac contractility, as estimated by measuring the maximum rate of rise of left ventricular pressure, and also in vascular resistance, estimated by measuring the pressure in a femoral artery perfused at constant flow. Heart rate was reduced significantly only when a dose of 4 mg kg⁻¹ was used.The cardiovascular responses observed in the intact animal were also present after cardiac sympathetic block with propranolol and denervation of the limb or after administration of histamine H₁ and H₂ receptor antagonists. This suggests that the responses were due to the direct action of chloroquine on the heart and blood vessels.