The functional significance of the 10-Hz sympathetic rhythm: a hypothesis

This paper reviews work from our laboratory on the 10-Hz rhythm in sympathetic nerve discharge of the cat and offers a hypothesis on its functional significance. The rhythm is ubiquitous to the discharges of sympathetic nerves with different cardiovascular targets and arises from a system of coupled nonlinear brain stem oscillators, each of which has a selective relationship with a different portion of the spinal sympathetic outflow. The 10-Hz rhythmic discharges of sets of sympathetic nerves are differentially related and the pattern of relationships in one experiment can be the reverse of that in the next. We hypothesize that nonuniform and dynamic coupling of the central circuits controlling different sympathetic nerves is the basis for the formulation of complex cardiovascular response patterns that include differential changes in regional blood flows.