Himura Y, Liang C S, Delehanty J M, Hood W B
Department of Medicine (Cardiology Unit), University of Rochester Medical Center, NY 14642.
J Cardiovasc Pharmacol. 1994 Nov;24(5):702-6. doi: 10.1097/00005344-199424050-00003.
To determine if nitroprusside improves arterial baroreflex responsiveness in chronic congestive heart failure (CHF), we administered nitroprusside to 11 conscious dogs with pacing-induced CHF. Baroreflex sensitivity was determined by plotting the R-R interval against systolic aortic pressure after a bolus injection of phenylephrine (PE). At baseline, dogs with CHF had higher heart rate (HR), increased left atrial blood pressure (BP), and reduced left ventricular (LV) dP/dt as compared with 10 sham-operated normal animals. Baroreflex sensitivity index was significantly lower in CHF dogs, (8.3 +/- 1.3 ms/mm Hg) than normal dogs (25.1 +/- 1.2 ms/mm Hg, p < 0.001). Intravenous (i.v.) administration of nitroprusside (1 microgram/kg/min) to CHF dogs decreased left atrial BP (23 +/- 1-17 +/- 1 mm Hg) and HR (131 +/- 4-115 +/- 4 beats/min), but had no significant effect on either cardiac output (CO) or systolic aortic BP. This resulted in a 58% increase in baroreflex sensitivity index to 13.1 +/- 1.3 ms/mm Hg (p < 0.001); and the change correlated significantly with magnitude of decrease in left atrial BP (r = 0.884, p < 0.001) but not with the increase in R-R interval (r = 0.390, p > 0.10). In contrast, administration of nitroprusside sufficient to decrease left atrial BP (9.0 +/- 1.4-6.4 +/- 1.2 mm Hg) did not alter baroreflex sensitivity (26.4 +/- 3.4-26.4 +/- 3.9 ms/mm Hg) in 5 normal dogs. The results suggest that nitroprusside infusion increases arterial baroreflex sensitivity only in dogs with CHF and that this effect is probably functionally linked to the reductions of cardiac filling pressure.
为了确定硝普钠是否能改善慢性充血性心力衰竭（CHF）患者的动脉压力感受器反射反应，我们对11只通过起搏诱导CHF的清醒犬给予硝普钠。通过在静脉注射去氧肾上腺素（PE）后绘制R-R间期与主动脉收缩压的关系来确定压力感受器反射敏感性。在基线时，与10只假手术正常动物相比，CHF犬的心率（HR）更高，左心房血压（BP）升高，左心室（LV）dP/dt降低。CHF犬的压力感受器反射敏感性指数（8.3±1.3毫秒/毫米汞柱）显著低于正常犬（25.1±1.2毫秒/毫米汞柱，p<0.001）。对CHF犬静脉注射（i.v.）硝普钠（1微克/千克/分钟）可降低左心房BP（23±1-17±1毫米汞柱）和HR（131±4-115±4次/分钟），但对心输出量（CO）或主动脉收缩压无显著影响。这导致压力感受器反射敏感性指数增加58%，达到13.1±1.3毫秒/毫米汞柱（p<0.001）；并且这种变化与左心房BP的降低幅度显著相关（r = 0.884，p<0.001），但与R-R间期的增加无关（r = 0.390，p>0.10）。相比之下，给予足以降低左心房BP（9.0±1.4-6.4±1.2毫米汞柱）的硝普钠对5只正常犬的压力感受器反射敏感性（26.4±3.4-26.4±3.9毫秒/毫米汞柱）没有改变。结果表明，硝普钠输注仅在CHF犬中增加动脉压力感受器反射敏感性，并且这种作用可能在功能上与心脏充盈压的降低有关。
