[Experimental study on the changes of blood pressure induced by afferent stimulation on the somatic nerves (author's...

It has been shown by many authors that afferent stimulation of various somatic nerves results in the different types of responses with regard to blood pressure and heart rate. It was revealed by Hunt that afferent "weak" stimulation of the somatic nerves caused depressor responses, and "strong" stimulation, pressor responses. Ranson and Gordon thought that the depressor response to the afferent stimulation of the somatic nerves would involve the thick myelinated nerve fibers, and the pressor response, the fine non-myelinated nerve fibers. On the other hand, it has been postulated that the socalled chest pain and/or nonspecific complaints observed in patients with myocardial infarction, angina pectoris and neurocirculatory asthenia (NCA) are related to some alterations at the cervical and thoracic vertebral levels of the spinal cord or nerve roots. Maekawa, Hayase and Konishi attached importance to the presence of subclinical arachnoiditis adhesiva cerebrospinalis at the cervical and thoracic vertebral levels in patients of NCA. These facts suggests that the contribution of the spinal cord and the nerve roots to the circularoty system is different between the cervico-thoracic levels and the lumbar levels. Based on these facts, the author stimulated the somatic nerves of both the forelimbs and the hindlimbs afferently in alpha-chloralose anesthetized dogs, with a train of square electric pulses for 20 seconds, and studied the response of the circulatory system to such stimuli.