Farhi E R, Cant J R, Paganelli W C, Dzau V J, Barger A C
Department of Physiology and Biophysics, Harvard Medical School, Boston, Mass.
Circ Res. 1987 Nov;61(5):670-7. doi: 10.1161/01.res.61.5.670.
We investigated the effect of converting enzyme inhibition (CEI) on the relationship between renal perfusion pressure (RPP) and steady-state plasma renin activity (PRA) in uninephrectomized conscious dogs on normal-salt (80 meq Na+/day) and low-salt (10 meq Na+/day) diets. Stimulus-response curves for the renal baroreceptor were determined by measuring the steady-state PRA while the RPP was lowered and then held constant by an inflatable cuff placed around the renal artery. On each diet the control stimulus-response curve can be described by two lines intersecting at a threshold pressure; in the higher pressure range PRA is relatively insensitive to changes in RPP, while in the lower pressure range PRA is very responsive to changes in RPP. On the normal-salt diet CEI significantly increases the sensitivity of PRA to RPP in the responsive range without affecting the threshold pressure itself or the values of PRA at pressures greater than the threshold pressure. On the low-salt diet CEI also increases the sensitivity of PRA to RPP significantly in the responsive range; we were unable to determine the effect of CEI on PRA at RPPs greater than the threshold pressure in the low-salt state because CEI causes a significant drop in blood pressure under these circumstances. The effect of CEI was significantly greater in the dogs on the low-salt diet than in the dogs on the normal-salt diet. Thus, CEI and salt depletion interact synergistically to increase the sensitivity of the renal baroreceptor only in the responsive range of the stimulus-response curve, i.e., at renal perfusion pressures below the threshold pressure.
我们研究了在正常盐（80 毫当量钠/天）和低盐（10 毫当量钠/天）饮食条件下，转换酶抑制（CEI）对单侧肾切除清醒犬肾灌注压（RPP）与稳态血浆肾素活性（PRA）之间关系的影响。肾压力感受器的刺激 - 反应曲线通过测量稳态 PRA 来确定，同时通过围绕肾动脉放置的可充气袖带降低 RPP 并使其保持恒定。在每种饮食条件下，对照刺激 - 反应曲线可用两条在阈值压力处相交的线来描述；在较高压力范围内，PRA 对 RPP 的变化相对不敏感，而在较低压力范围内，PRA 对 RPP 的变化非常敏感。在正常盐饮食下，CEI 在反应范围内显著增加 PRA 对 RPP 的敏感性，而不影响阈值压力本身或高于阈值压力时的 PRA 值。在低盐饮食下，CEI 在反应范围内也显著增加 PRA 对 RPP 的敏感性；由于在这些情况下 CEI 会导致血压显著下降，我们无法确定 CEI 对低盐状态下高于阈值压力的 RPP 时 PRA 的影响。CEI 对低盐饮食犬的影响显著大于对正常盐饮食犬的影响。因此，CEI 和盐耗竭仅在刺激 - 反应曲线的反应范围内，即在低于阈值压力的肾灌注压下协同相互作用，以增加肾压力感受器的敏感性。
