Resetting of aortic baroreceptors in experimental hypertension and atherosclerosis

The dependence of aortic baroreceptor activity on aortic pressure and aortic distension was studied in isolated preparations "aortic arch--aortic nerve", obtained from normal rabbits and from rabbits with experimental hypertension and atherosclerosis varying in duration. It was found that in both atherosclerosis and hypertension the reactivity thresholds of aortic baroreceptors shifted toward higher pressures. In initial stages of hypertension and atherosclerosis this resetting results from changes in the baroreceptive zone itself, and aortic distensibility does not differ from the normal state. In later stages of hypertension and atherosclerosis the aortic distensibility decreases; in consequence of this the shift of baroreceptor reactivity threshold increases. Possible mechanism of baroreceptor resetting and its role in the regulation of arterial pressure in hypertension and atherosclerosis are discussed.