Renal intracortical blood flow and renin secretion after denervation by 6-hydroxydopamine

Abstract

A new method of unilateral renal denervation (DNX) was developed in dogs by rapidly injecting 6-hydroxydopamine (6-OHDA) into the renal artery with simultaneous collection of the venous effluent to avoid systemic effects. The procedure induced a 93.1 ± 2.7% destruction of the adrenergic innervation as assessed by a histochemical fluorescence technique. A comparative study of both kidneys was carried out 3 days after DNX. Renal blood flow (RBF) and its cortical distribution were measured with radioactive microspheres at mean perfusion pressures of 117 mmHg (1 mmHg = 133.322 Pa) (normotension) and 70 mmHg (hypotension). The comparison of renal perfusion between kidney halves revealed a remarkable perfusion symmetry during normotension and hypotension in both the intact and the DNX kidney. Renal DNX by 6-OHDA did not alter RBF when the kidneys were perfused at normotension. During hypotension, RBF fell by 45% on the control side, while a nonsignificant decrease was noted in the DNX kidney. The redistribution of blood flow to inner cortical zones was less marked in the DNX side during hypotension. The DNX kidney did not release renin during normotension, but exhibited a normal renin response to hypotension. These data are partly in agreement with classical denervation models, and indicate that (1) denervation by 6-OHDA protects renal perfusion during hypotension; and (2) the redistribution of blood flow to inner cortical nephrons is independent of release of renin, but modulated by adrenergic innervation.