1. The effect of adrenaline and noradrenaline on renin secretion in the isolated perfused rat kidney was examined. The doses of catecholamines used were such that renal vasoconstriction and therefore increases in renal perfusion pressure were avoided. Under these conditions adrenaline and noradrenaline significantly increased renin secretion rates, compared with control experiments in which no catecholamine was infused.
2. Mean renal perfusion pressure during both adrenaline and noradrenaline infusion paralleled the control study by showing a progressive fall.
3. Administration of phenoxybenzamine did not impair the stimulation of renin secretion by adrenaline whereas this was prevented by racemic propranolol.
4. These observations suggest that catecholamines stimulate renin secretion by an intrarenal effect which is largely independent of changes in renal perfusion pressure. It is postulated that the beta-adrenoceptors mediating renin secretion are an integral component of the renin-producing cell.