Pressoreceptor-Autonomic Oscillation: A Probable Cause of Vasomoter Waves

Abstract

A study of vasomotor waves in dogs showed that factors which block either the pressoreceptor system or the sympathetic nervous system will cause vasomotor waves to disappear. The period of reaction of the pressoreceptor reflex is of proper duration to explain the period of oscillation noted in the vasomotor waves. The theory of oscillation in regulatory systems is briefly discussed. The pressoreceptor-autonomic nervous reflex system satisfies the 2 essential conditions for oscillation, i.e., a negative reflex and a time delay in the circuit. Pressoreceptor-autonomic oscillation may be explained as follows: The blood pressure rises; this stimulates the pressoreceptors; the sympathetics are inhibited and the vagi are excited; the blood pressure falls. This diminishes the excitation of the pressoreceptors; the sympathetics are released from their inhibition and the vagi are no longer excited; the blood pressure rises again; and the cycle repeats itself indefinitely until some dampening factor intervenes. Such oscillation may exist in the waxing, sustained, or dampened form depending on the relative power of the reflex driving force and the dampening factors. Each of these 3 forms has been demonstrated in vasomotor waves by varying the driving force of the pressoreceptor-autonomic reflex.