Mendelowitz D, Scher A M
Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195.
Am J Physiol. 1990 Jan;258(1 Pt 2):H92-100. doi: 10.1152/ajpheart.1990.258.1.H92.
In a previous study [Am. J. Physiol. 255 (Heart Circ. Physiol. 24): H673-H678, 1988] we demonstrated that baroreflex responses decay (reset) to increased static sinus pressures, but with increased pulsatile pressure, responses are maintained. To determine more conclusively whether pulsatile pressure prevents rapid baroreflex resetting in this study we examined resetting as shifts of the baroreflex (sinus pressure-arterial pressure) curve. In seven anesthesized rabbits the left sinus was vascularly isolated and conditioned for 5 min to static or pulsatile pressures of 60, 100, or 140 mmHg mean pressure, 0 or 35-40 mmHg pulse pressure. The baroreflex curve was then determined by stepwise changing sinus pressure from 40 to 160 mmHg in 20-mmHg increments. Threshold, midpoint, and saturation sinus pressures shifted 25-39% with static conditioning pressures but did not shift significantly with pulsatile pressures. Also, the baroreflex responses to step increases in static sinus pressure decayed, as resetting occurred, but did not decay with pulsatile sinus pressure increases. Thus the baroreflex rapidly resets with static pressures, but there is minimal, if any, resetting with pulsatile pressures.
在之前的一项研究中[《美国生理学杂志》255卷（心脏循环生理学24）：H673 - H678，1988年]，我们证明压力感受性反射对静态窦压力升高的反应会衰减（重置），但随着脉动压力升高，反应得以维持。为了更确切地确定在本研究中脉动压力是否能防止压力感受性反射快速重置，我们将压力感受性反射（窦压力 - 动脉压力）曲线的移位作为重置来进行研究。在7只麻醉的兔子中，将左窦进行血管隔离，并使其适应平均压力为60、100或140 mmHg，脉压为0或35 - 40 mmHg的静态或脉动压力5分钟。然后通过以20 mmHg的增量将窦压力从40逐步改变到160 mmHg来确定压力感受性反射曲线。阈值、中点和饱和窦压力在静态调节压力下移位了25 - 39%，但在脉动压力下没有显著移位。此外，随着重置的发生，压力感受性反射对静态窦压力逐步升高的反应会衰减，但对脉动窦压力升高则不会衰减。因此，压力感受性反射在静态压力下会快速重置，但在脉动压力下即使有重置也极小。
