Effects of endothelin on adrenergic neurotransmission in the dog kidney

Endothelin infused into the renal artery (0.3-3 ng/kg per min) of anesthetized dogs suppressed the increases in renal venous plasma norepinephrine (NE) concentration and calculated NE efflux induced by renal nerve stimulation at low frequencies (0.7-1.2 Hz) but not at high frequencies (2-3.5 Hz). Endothelin failed to affect the decrease in renal blood flow induced by renal nerve stimulation or exogenous NE. These findings suggest that endothelin inhibits NE release during a slight rise in renal nerve activity, while it does not affect alpha-adrenoceptor-mediated vasoconstriction in the dog kidney.