DYNAMIC TRANSDUCTION PROPERTIES OF IN-SITU BARORECEPTORS OF RABBIT AORTIC DEPRESSOR NERVE

We developed a new method for isolating in situ baroreceptor regions o f the rabbit aortic depressor nerve (ADN) and estimated the transfer f unction from pressure to afferent nerve activity in the frequency rang e of 0.01-5 Hz by a white noise technique. Complete isolation of the b aroreceptor area of the right ADN was made in situ by ligation of the innominate artery and the right subclavian and common carotid arteries . We altered the pressure in the isolated baroreceptor area according to a binary quasi-white noise between 80 and 100 mmHg in 12 urethan-an esthetized rabbits. The gain increased two to three times as the frequ ency of pressure perturbation increased from 0.01 to 2 Hz and then dec reased at higher frequencies. The phase slightly led below 0.2 Hz. The squared coherence value was >0.8 in the frequency range of 0.01-4 Hz. The step responses estimated from the transfer function were indistin guishable from those actually observed. We conclude that the barorecep tor transduction of the ADN is governed by linear dynamics under the p hysiological operating pressure range.