OBJECTIVES: To study the effects of denervation of the kidney on renal vascular resistance at maximal dilatation and renal function during the development of hypertension in the spontaneously hypertensive rat (SHR). METHODS: SHR aged 6 weeks were subjected to left renal denervation or a sham-operation (n = 18 denervated, n = 13 sham). When they were aged 10 weeks, pairs of denervated and sham-operated left kidneys were perfused with 2% dextran in Tyrode's solution and pressure-flow and pressure-glomerular filtration rate (GFR) relationships at maximal vasodilation were established. The awake mean arterial blood pressure, in-vivo renal function and renal noradrenaline content were also measured. RESULTS: There were no significant differences between the pressure-flow relationships for denervated and sham-operated kidneys. However, there was a marked, parallel, shift leftwards in the pressure-GFR relationship (P < 0.001). Thus, the denervated kidneys commenced filtering at a lower threshold perfusion pressure than did the sham-operated ones. In-vivo renal plasma flow and GFR were significantly greater in the denervated left kidneys of SHR than they were in the contralateral kidneys. The noradrenaline content in denervated kidneys was 5 +/- 3% of that in innervated kidneys. The awake mean arterial pressure was 135 +/- 1 and 138 +/- 2 mmHg in the denervated and sham-operated groups respectively. CONCLUSION: Denervation of the kidney of SHR aged 6 weeks of age altered the pressure-GFR but not the pressure-flow relationship for these rats 4 weeks later. The results are compatible with there having been an increase in average preglomerular and a decrease in post-glomerular vessel lumen diameters. These changes suggest that the renal nerves affect the structural development of the renal vasculature in SHR.
OBJECTIVES: To study the effects of denervation of the kidney on renal vascular resistance at maximal dilatation and renal function during the development of hypertension in the spontaneously hypertensiverat (SHR). METHODS: SHR aged 6 weeks were subjected to left renal denervation or a sham-operation (n = 18 denervated, n = 13 sham). When they were aged 10 weeks, pairs of denervated and sham-operated left kidneys were perfused with 2% dextran in Tyrode's solution and pressure-flow and pressure-glomerular filtration rate (GFR) relationships at maximal vasodilation were established. The awake mean arterial blood pressure, in-vivo renal function and renal noradrenaline content were also measured. RESULTS: There were no significant differences between the pressure-flow relationships for denervated and sham-operated kidneys. However, there was a marked, parallel, shift leftwards in the pressure-GFR relationship (P < 0.001). Thus, the denervated kidneys commenced filtering at a lower threshold perfusion pressure than did the sham-operated ones. In-vivo renal plasma flow and GFR were significantly greater in the denervated left kidneys of SHR than they were in the contralateral kidneys. The noradrenaline content in denervated kidneys was 5 +/- 3% of that in innervated kidneys. The awake mean arterial pressure was 135 +/- 1 and 138 +/- 2 mmHg in the denervated and sham-operated groups respectively. CONCLUSION: Denervation of the kidney of SHR aged 6 weeks of age altered the pressure-GFR but not the pressure-flow relationship for these rats 4 weeks later. The results are compatible with there having been an increase in average preglomerular and a decrease in post-glomerular vessel lumen diameters. These changes suggest that the renal nerves affect the structural development of the renal vasculature in SHR.