Sympathetic-renal interaction in chronic arterial pressure control

The effects of neonatal sympathectomy of donors or recipients on post-transplantation arterial pressure were investigated in spontaneously hypertensive rats (SHR) by renal transplantation experiments. Conscious mean arterial pressure (MAP) and renal vascular resistance were 136 [+ or -] 1 mmHg and 15.5 [+ or -] 1.2 mmHg * [ml.sup.-1] * min * g in sympathectomized SHR (n = 8) vs. 158 [+ or -] 4 mmHg (P < 0.001) and 20.8 [+ or -] 1.1 mmHg * [ml.sup.-1] * min * g (P < 0.05) in controls (n = 10). Seven weeks after transplantation of a kidney from neonatally sympathectomized SHR donors, MAP in SHR recipients (n = 10) was 20 mmHg lower than in controls transplanted with a kidney from hydralazine-treated SHR (n = 10) (P < 0.05) associated with reduced sodium sensitivity of MAP. Neonatal sympathectomy also lowered MAP in F1-hybrids (F1H; SHR x Wistar-Kyoto rats). Within 6 wk after transplantation, renal grafts from untreated SHR increased MAP by 20 mmHg in sympathectomized F1H (n = 10) and by 35 mmHg in sham-treated F1H (n = 8) (P < 0.05). Neonatal sympathectomy induces chronic changes in SHR kidney function leading to a MAP reduction even when extrarenal sympathetic tone is restored. Generalized reduction in sympathetic tone resets the kidney-fluid system to reduced MAP and blunts the extent of arterial pressure rise induced by an SHR kidney graft. rats; inbred strains; kidney transplantation; sodium; catecholamines; guanethidine