Effect on renal function and renin secretion of noradrenaline infused into the renal artery

Effect of noradrenaline on renal function and renin secretion was studied during infusion into the renal artery of anaesthetized dogs. Experiments were performed with or without alpha or beta receptor blockade. Noradrenaline infusion resulted in a significant elevation of renin secretion associated with marked vasoconstriction. Urine flow rate, the filtered and excreted amounts of sodium were diminished due to the decreased GFR. Alpha receptor blockade suppressed renin secretion in the presence of changes in renal haemodynamics. The simultaneous infusion of noradrenaline enhanced renin release without affecting renal haemodynamics or reducing Na-excretion. Following simultaneous inhibition of alpha and beta receptors renin secretion dropped markedly; there were no further changes in either renin secretion or renal haemodynamics upon the simultaneous administration of noradrenaline. Based on the present findings it is suggested that renin secretion is controlled by both alpha and beta receptors. Beta receptor simulation exerts a direct action, whereas alpha stimulation appears to be mediated in part by indirect mechanisms such as renal haemodynamics.