Sympathoadrenal and renin-angiotensin systems in the development of two-kidney, one clip renal hypertension in rats.

Abstract

SUMMARYThe relative roles of tbe sympathetic nerrous system and renin-angiotefisin system in the development of two-kidney renal hypertension were studied using four groups of rats: Group I = vehicle control; Group II = 6-OH-dopamine (2 weeks prior to renal clipping then weekly throughout the study); Group III = adrenal medullectomy plus vehicle; Group IV = o-OHndopamlne plus adrenal medullectomy. Six weeks after clipping of a single renal artery, plasma renln activity (PRA) was comparably elevated in all groups. However, mean blood pressure (MBP) of Group II was lower than that of Group I controls (154.

Sympatho-Adrenal System and the Kidney in Hypertension

“…Tyrosine-hydroxylase, and dopamine (5-hydroxylase activities and the concentration of NE were increased in the hypothalamus of one-kidney, one clip hypertension [47], Furthermore, plasma NE was increased 62% in the same model [47], NE turnover was shown to be increased in the aorta and mesenteric artery of one-kidney, one clip but not in the two-kidney, one clip model in the rabbit [48]. Guanethidine further decreased blood pressure to normal lev els in chronic two-kidney, one clip hypertensive rats receiving normally effective doses of captopril and hydrochlorothizide [46], Adrenal medullectomy alone was without effect on the development of the two-kidney, one clip model. However, this procedure had additive hypo tensive effect when combined with sympathectomy at 6 and 12 weeks after placement of the clip [46], The mechanism responsible for the activation of the SNS in this form of hypertension is not known.…”

“…Central sympathectomy with 6-hydroxydopamine [46] and le sions of the AV3V area of the brain [30] prevented the increase in blood pressure in the one-kidney, one clip and in the two-kidney, one clip hypertension, as well as in the one-kidney, one figure-8 hypertension. Similar results can be obtained with peripheral sympathectomy by 6-hydroxydopamine or with immunosympathectomy.…”

Importance of the renal nerves in established two-kidney, one clip Goldblatt hypertension.

“…9 -" For example, unclipping which restored blood pressure to normal levels was accompanied by decreased activity of the reninangiotensin system as well as a decrease in peripheral sympathetic activity. The response to SQ 20,881 provides further evidence that the renin-angiotensin system is partially responsible for the maintenance of the hypertension.…”

Pre- and postjunctional inhibition of vascular sympathetic function by captopril in SHR. Implication of vascular angiotensin II in hypertension and antihypertensive actions of captopril.

“…There is now little doubt that the sympathetic nervous system plays an important contributory role in the maintenance of twokidney RHR, a role that grows more important as the duration of hypertension increases. 21 " 23 Similarly, the sympathetic nervous system is important in the development as well as the maintenance of hypertension in SHR. Thus, drugs that interfere with sympathetic function are effective in reducing both chronic renal and spontaneous hypertension.…”