EFFECT OF INTRAVENOUSLY INFUSED NORADRENALINE ON CARDIOVASCULAR-SYSTEM OF COLD-ACCLIMATED RATS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 26  (5) , 397-404
Abstract
Total metabolism, body temperature and basic circulatory parameters (the heart rate, blood pressure, blood oxygen content and hind limb blood flow) were measured in unanesthetized cold-acclimated male rats exposed to the calorigenic action of noradrenaline. Cardiac output, the O2 extraction coefficient and peripheral vascular resistance were calculated from these data. The infusion of noradrenaline (1-6 .mu.g/kg per min) was accompanied by an increase in total metabolism, cardiac output, the O2 extraction coefficient, the heart rate and pressure in the aorta and the femoral artery, which was porportional to the rising dose. After a dose of 2 .mu.g/kg per min, the blood flow in the femoral artery was higher than the resting value, but after doses of 4-6 .mu.g/kg per min it was lower. These changes in the hind limb blood flow in the presence of increased cardiac output, and the changes in peripheral resistance in the presence of constant systemic resistance, are evidence of the autonomic effect of noradrenaline on vasomotor function in the hind limb.

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