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+/-1 mmHg and 15.5+/-1.2 mmHg.ml(-1).min.g in sympathectomized SHR (n=8) vs. 158+/-4 mmHg (P<0.001) and 20.8±1.1 mmHg.ml(-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.