RENAL SYMPATHETIC NEUROEFFECTOR FUNCTION IN RENOVASCULAR- AND ANGIOTENSEVII-DEPENDENT-HYPERTENSION IN RABBITS

摘要

Background: There is evidence that an increased influence of the sympathetic nervous system, particularly on renal function, contributes to the development and/or maintenance of hypertension induced by unilateral renal artery clipping (2K1C) or chronic angiotensin II infusion (Ang II). However, renal sympathetic nerve activity (RSNA) per se is not increased in these forms of hypertension. This paradox might be explained if the sensitivity of the kidney to sympathetic outflow is increased in 2K1C- and Ang II-hypertension.Aim: To determine whether the gain of renal sympathetic neuro-effector mechanisms is increased in Ang II- and 2K1 C-hypertension in rabbits.Methods: Chronic hypertension of similar severity (-20% above baseline) was produced by subcutaneous infusion of Ang II (20-50 ng/kg/min; n = 9), or by placing a clip on either the left (n = 7) or right (n = 6) renal artery (2K1C). Another group of rabbits underwent sham surgery (n = 8). Four to six weeks later, all rabbits then underwent an experiment under pentobarbitone anaesthesia (90-150 mg plus 30-50 mg/h), during which the renal nerves were stimulated reflexively (hypoxia - 10% O_2) and electrically (0.5-2 Hz at maximal voltage). Responses of renal haemodynamics, excretory function, and renal renin release, of the left kidney were measured.