Vassallo D V, Vasquez E C, Mill J G, Cabral A M
Departamento de Ciências Fisiológicas, Centro Biomédico, UFES, Victoria, ES, Brazil.
Am J Physiol. 1991 Sep;261(3 Pt 2):H639-43. doi: 10.1152/ajpheart.1991.261.3.H639.
Sinoaortic baroreceptor denervation (SAD) in the rat immediately produces hypertension and tachycardia, as the result of an increased sympathetic tone to the heart and resistance vessels. Adaptive processes are then installed, changing according to the duration of the SAD. In this work we studied the time course of adaptive changes occurring in the rat heart within a 30-day period. Heart rate and mean blood pressure were measured before mechanical studies in the isometrically contracting left ventricle papillary muscles. Results showed that heart rate and mean blood pressure increased immediately after the SAD. Heart rate normalized 15 days later, although hypertension persisted. Thirty days later both rate and pressure normalized. Mechanical studies showed that isometric force development (F) and its first-time derivative (dF/dt) behaved similar to controls until the 1st wk but displayed a contractile depression in the 2nd wk after SAD. However, after 30 days this depression subsided and both F and dF/dt were back to normal values. The beta-adrenoceptor responsiveness also changed during this 30-day period. Three days after denervation there was an increased sensitivity to isoproterenol action in the muscles. This sensitivity was progressively reduced as the time after denervation increased. The absence of a similar behavior with the rest-potentiated contractions suggests that these time-course adaptive changes are specific for beta-adrenoceptor stimulation.
大鼠的窦主动脉压力感受器去神经支配（SAD）会立即导致高血压和心动过速，这是由于心脏和阻力血管的交感神经张力增加所致。随后会启动适应性过程，并根据SAD的持续时间而变化。在这项研究中，我们研究了30天内大鼠心脏发生的适应性变化的时间进程。在对等长收缩的左心室乳头肌进行力学研究之前，测量心率和平均血压。结果显示，SAD后心率和平均血压立即升高。15天后心率恢复正常，尽管高血压仍然存在。30天后，心率和血压均恢复正常。力学研究表明，等长力发展（F）及其一阶导数（dF/dt）在第1周之前的表现与对照组相似，但在SAD后的第2周出现收缩抑制。然而，30天后这种抑制消退，F和dF/dt均恢复到正常值。在这30天内，β-肾上腺素能受体反应性也发生了变化。去神经支配3天后，肌肉对异丙肾上腺素作用的敏感性增加。随着去神经支配时间的增加，这种敏感性逐渐降低。静息增强收缩没有类似的表现，这表明这些时间进程的适应性变化是β-肾上腺素能受体刺激所特有的。
