EFFECTS OF NISOLDIPINE ON CARDIOCIRCULATORY DYNAMICS AND CARDIAC-OUTPUT DISTRIBUTION IN CONSCIOUS RATS AT REST AND DURING TREADMILL EXERCISE

  • 1 January 1985
    • journal article
    • research article
    • Vol. 232  (2) , 376-381
Abstract
The effects of the dihydropyridine derivative nisoldipine (1.6 .mu.g/kg per min) on hemodynamics and regional blood flow (radioactive microspheres 15 .+-. 5 .mu.m) were examined in conscious rats at rest and during treadmill exercises (35 feet/min, 5 min). Nisoldipine significantly reduced systemic vascular resistance (-38%) and mean arterial pressure (-17%) and increased heart rate (P < 0.05). Skeletal muscle blood flow was increased and vascular resistances in the skeletal muscle, in renal and coronary arteries and in part of the gut circulations were significantly reduced (all P < 0.05). Left ventricular end-diastolic pressure was unchanged by the drug both at rest and during exercise. At exercise, nisoldipine significantly increased skeletal muscle blood flow in 4 of 8 skeletal muscle regions investigated; the increase in total skeletal muscle flow was less pronounced compared to the changes at rest. The vasodilator effect of nisoldipine in the renal and splanchnic circulations was markedly attenuated by the exercise-induced vasoconstriction in these circulatory beds. Nisoldipine is apparently a potent vasodilator of skeletal muscle and coronary and renal arteries. It appears to possess highly selective effects on vascular smooth muscle as compared to its direct cardiac effects.