Selective effect of tempol on renal medullary hemodynamics in spontaneously hypertensive rats

被引:36
作者
Feng, MG [1 ]
Dukacz, SAW [1 ]
Kline, RL [1 ]
机构
[1] Univ Western Ontario, Dept Physiol, London, ON N6A 5C1, Canada
关键词
arterial pressure; nitric oxide; renal medulla; kidney; hypertension; angiotensin II;
D O I
10.1152/ajpregu.2001.281.5.R1420
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
The present study assessed the short- and long-term effect of tempol, a membrane-permeable mimetic of superoxide dismutase, on renal medullary hemodynamics in spontaneously hypertensive rats (SHR). Tempol was given in the drinking water (1 mM) for 4 days or 7 wk (4-11 wk of age), and medullary blood flow (MBF) was measured over a wide range of renal arterial pressure by means of laser-Doppler flowmetry in anesthetized rats. In addition, the response of the medullary circulation to angiotensin II (5-50 ng . kg(-1) . min(-1) iv) was determined in SHR treated for 4 days with tempol. Compared with control SHR, short- and long-term treatment with tempol decreased arterial pressure by similar to 20 mmHg and increased MBF by 35-50% without altering total renal blood flow (RBF) or autoregulation of RBF. Angiotensin II decreased RBF and MBF dose dependently (similar to 30% at the highest dose) in control SHR. In SHR treated with tempol, angiotensin II decreased RBF (similar to 30% at the highest dose) but did not alter MBF significantly. These data indicate that the antihypertensive effect of short- and long-term administration of tempol in SHR is associated with a selective increase in MBF. Tempol also reduced the sensitivity of MBF to angiotensin II. Taken together, these data support the idea that tempol enhances vasodilator mechanisms of the medullary circulation, possibly by interacting with the nitric oxide system. Increased MBF and reduced sensitivity of MBF to angiotensin II may contribute to the antihypertensive action of tempol in SHR.
引用
收藏
页码:R1420 / R1425
页数:6
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