Aortic Baroreceptor Activity in Normal and Hypertensive Rabbits

The baroreceptor activity in the entire left aortic nerve was recorded in 9 normal and 5 hypertensive rabbits. A technique based on rectification and integration of the nerve potentials allowed separate analysis of the mean, systolic and diastolic activities. The nervous activities measured at different diastolic blood pressures showed only small variations during recordings over several hours. and small inter‐individual variations. In hypertensive rabbits, the receptors required a higher pressure to start firing than in normal rabbits. The activity was lower at all pressures in hypertensive animals. The difference from normal rabbits increased with increasing pressure, and was most pronounced for the systolic part of the firing. Mechanisms for causing the resetting of baroreceptor activity in hypertension are discussed. It is concluded that a combination of hypertensive wall changes and exhaustion or destruction of some receptors is probably responsible for the resetting.