Shammas R A, Denison A L, Pfennig T W, Hemker D P, Stephenson R B
Department of Physiology, Michigan State University, East Lansing 48824.
Am J Physiol. 1988 Jun;254(6 Pt 2):R1025-34. doi: 10.1152/ajpregu.1988.254.6.R1025.
Previous studies showed that baroreflex control of heart rate is impaired during operant shock avoidance conditioning and classical aversive conditioning. However, the effects of such "emotionally stressful" paradigms on the ability of the baroreflex to control arterial pressure have not been directly assessed. We prepared the carotid sinus regions of dogs for reversible isolation from the systemic circulation, and we derived complete stimulus-response relations for the effects of carotid sinus pressure on both heart rate and arterial pressure. For any given carotid sinus pressure, arterial pressure and heart rate were higher during operant shock-avoidance conditioning and during classical aversive conditioning than in a neutral environment, which indicates an upward resetting of the baroreflex. However, threshold and saturation carotid sinus pressures were unaffected by operant conditioning or classical conditioning, which indicates that the baroreceptors themselves were not reset. The ranges over which the carotid baroreflex could vary arterial pressure and heart rate were significantly increased during both operant conditioning and classical conditioning. Baroreflex gain was unchanged during operant conditioning and was significantly increased during classical conditioning. We conclude that the baroreflex is not impaired during operant shock-avoidance conditioning or classical aversive conditioning in dogs. However, the baroreflex is reset and regulates blood pressure at an elevated level.
先前的研究表明，在操作性休克回避条件反射和经典厌恶条件反射过程中，压力感受性反射对心率的控制会受到损害。然而，此类“情绪应激”范式对压力感受性反射控制动脉血压能力的影响尚未得到直接评估。我们对犬的颈动脉窦区域进行制备，使其与体循环可逆性隔离，并得出了颈动脉窦压力对心率和动脉血压影响的完整刺激-反应关系。对于任何给定的颈动脉窦压力，在操作性休克回避条件反射期间和经典厌恶条件反射期间，动脉血压和心率均高于中性环境中的水平，这表明压力感受性反射发生了向上重置。然而，阈值和饱和颈动脉窦压力不受操作性条件反射或经典条件反射的影响，这表明压力感受器本身并未重置。在操作性条件反射和经典条件反射期间，颈动脉压力感受性反射能够改变动脉血压和心率的范围均显著增加。在操作性条件反射期间压力感受性反射增益未变，而在经典条件反射期间显著增加。我们得出结论，在犬的操作性休克回避条件反射或经典厌恶条件反射过程中，压力感受性反射并未受损。然而，压力感受性反射被重置，并在升高的水平上调节血压。
