Role of cardiac nerves in determination and modulation of blood pressure oscillation pattern

Effects of autonomic innervation of the heart for blood pressure oscillation (BPO) caused by a side pressure exertion procedure in rabbits were studied by intravenous administrations of atropine or beta-blockers (metoprolol and propranolol). When relatively large doses of these drugs were injected the oscillation disappeared. Atropine injection caused three types of effects on BPO: mostly abolition, diminution and sometimes augmentation. In the diminished cases, the oscillation waves were subjected to a successive decrease in the height and the gradient of ascending limbs. And the extent of bradycardia on the descending limb was less than that of the control. In the augmented cases which accounted for one fifth of all the results, the injection enhanced the BPO in wave height and gradient. Meanwhile, the administration of beta-blockers resulted in disappearance or a decrease in wave height and gradient of the ascending limbs of waves. From these, it is suggested that cardiac sympathetic and vagal discharges accelerate blood pressure rise of the ascending limb, and vagal discharges contribute to active descent of each wave. It is suggested that the BPO is influenced not only by the periodic change of the total peripheral resistance but also by the concomitant changes in tones of cardiac nerves.