The Effects of Autonomic Nervous System Inhibition on the Circulatory Response to Muscular Exercise.

One of the primary functions performed by the cardiovascular system is the delivery of oxygen and metabolic substrates to the peripheral tissues during varying levels of their activity. Accordingly, the manner in which the circulation is altered during muscular activity and the consideration that the cardiovascular response is mediated through the interaction of a number of mechanisms, prominent among which is the activity of the autonomic nervous system, are of interest. The present investigation was undertaken in an attempt to clarify the role of this mechanism in normal human subjects by determining the manner in which inhibition of the parasympathetic and the sympathetic divisions, or both, affected the circulatory response to exercise. Two pharmacologic agents were employed to produce functional inhibition of the autonomic nervous system; atropine was used to inhibit the parasympathetic division, and guanethidine, an effective adrenergic blocking agent (1), was used to interfere with the activity of the sympathetic division.