Uchida Y
Am J Physiol. 1975 Jan;228(1):223-30. doi: 10.1152/ajplegacy.1975.228.1.223.
Mechanosensitivity of afferent sympathetic nerve fibers from the right heart and the pulmonary artery has been examined. Action potentials of the afferent fibers that responded to tapping the right heart and the pulmonary artery were derived from upper thoracic communicating rami of both sides of anesthetized dogs. The fibers were composed of myelinated Adelta fibers and unmyelinated fibers. The receptive fields of both groups of fibers were located widely in the right heart and the pulmonary artery. Myelinated fibers ceased to fire quickly whereas unmyelinated fibers continued to fire after withdrawl of a brief mechanical stimulus. In the myelinated group, the pressure threshold was 3-50, 6-58, and 3-10 mmHg for right ventricular, pulmonary and right atrial threshold was 15-58, 22-34, and 4-8 mmHg for right ventricular, pulmonary, and right atrial fibers, respectively. Spontaneous discharge of myelinated fibers was synchronous with each rise and/or fall in intracardiac or pulmonary pressure whereas that of unmyelinated fibers was irregular and independent. A rise in pressure produced by pulmonary embolization or occlusion caused an augumented discharge whereas a fall caused by caval vein occulsion eliminated the discharge. The results indicate the existence of both myelinated and unmyelinated fibers with mechanoreceptors in the right heart and the pulmonary artery.
已对来自右心和肺动脉的传入交感神经纤维的机械敏感性进行了研究。对轻敲右心和肺动脉有反应的传入纤维的动作电位取自麻醉犬双侧的胸上交通支。这些纤维由有髓鞘的Aδ纤维和无髓鞘纤维组成。两组纤维的感受野广泛分布于右心和肺动脉。有髓鞘纤维在短暂机械刺激撤除后迅速停止放电，而无髓鞘纤维在刺激撤除后仍继续放电。在有髓鞘纤维组中，右心室、肺动脉和右心房纤维的压力阈值分别为3 - 50、6 - 58和3 - 10 mmHg，右心室、肺动脉和右心房纤维的压力阈值分别为15 - 58、22 - 34和4 - 8 mmHg。有髓鞘纤维的自发放电与心内或肺动脉压力的每次升高和/或降低同步，而无髓鞘纤维的自发放电则不规则且独立。肺栓塞或阻塞引起的压力升高导致放电增加，而腔静脉阻塞引起的压力降低则消除放电。结果表明，在右心和肺动脉中存在有髓鞘和无髓鞘的机械感受器纤维。
