A comparison of the stimulus-response curves of aortic and carotid sinus baroreceptors in decerebrated cats

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Abstract
Recordings of total nerve activity suggested differences in the sensitivities and working ranges between aortic and carotid sinus baroreceptors. This result however, conflicts with single fibre studies from isolated receptor zones. Thus it appeared of some interest to compare the function curves of aortic and carotid sinus baroreceptors in the intact animal. This was achieved by comparing the response characteristics of two groups of aortic and carotid sinus baroreceptors in decerebrated cats. One smaller group consisted of 11 receptor pairs, each member of the pair being studied simultaneneously in the same cat, and a larger group consisting of 98 aortic and 49 carotid sinus baroreceptors studied independently of each other. The response of each receptor to wide pressure variations was recorded by inflating and deflating an intraaortic catheter tip balloon. Function curves were derived by plotting receptor discharge in terms of spikes per second against mean aortic pressure. No significant differences were found either in the slope of the function curves or their mean pressures at minimum activity, the latter appearing to be set by the working blood pressure level. Thus it was concluded that aortic and carotid sinus baroreceptors differ neither in their sensitivities nor in their working ranges when in their physiological environment.