Selective actions of calcium antagonistic drugs on the haemodynamics and regional organ blood flow in rats.
Six substances, all of which influence calcium utilization by smooth muscle, namely nimodipine (50 micrograms/kg), flunarizine (1 mg/kg), verapamil (0.2 mg/kg), lidoflazine (1 mg/kg), magnesium (600 mumol Mg++/kg), and manganese (180 mumol Mn++/kg), were given intravenously to rats and their effects on regional blood flows and on cardiac output were determined by the radioactive microsphere technique. All compounds caused a temporary fall in mean arterial blood pressure. Cardiac output was decreased by manganese, and minute work by nimodipine, manganese and lidoflazine. Nimodipine increased blood flow in the liver, skeletal muscle and heart and decreased that in the stomach, ileum, colon, kidney, spleen and skin; manganese increased flow in the duodenum, jejunum, liver and myocardium and decreased that in the stomach, ileum, colon, spleen and skin; flunarizine increased flow in the liver, heart and brain; and magnesium increased flow in the liver, spleen and brain. Lidoflazine and verapamil, although leading to haemodynamic alterations, had no selective effect on organ blood flow. Selective actions by calcium effector drugs can provide information on mechanisms of calcium flux in various types of vascular smooth muscle, and show that it is possible to tailor combinations of anti-calcium agents with optimal effects on a given organ.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002302:Cardiac Output / Q000187:drug effects*; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects*; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012039:Regional Blood Flow / Q000187:drug effects*
D002121:Calcium Channel Blockers; D008345:Manganese; D008274:Magnesium