Effects of clonidine on vascular responses in kidney and hindlimbs of cats.

1. Cardiovascular reflexes to intravenous adrenaline and histamine and to carotid occlusion were studied in the renal vasculature, and direct effects of noradrenaline and clinidoine were compared in renal and hindlimb vascular beds in anaesthetized cats. 2. Unlike its reported effects on cardiovascular reflexes in the hindlimbs, clonidine depressed all three reflexes in the kidneys. 3. Noradrenaline caused vasoconstriction when given directly into both renal and hindlimb circulartions, but clonidine produced vasoconstriction only in the hindlimb vascular bed. 4. These results suggest that alpha-adrenoceptors in the reanl vasculature may be different from those in the hindlimbs, and that the cardiovascular reflexes in these two areas are under different control.