CAROTID CHEMORECEPTORS INFLUENCE ARTERIAL-PRESSURE IN INTACT AND AORTIC-DENERVATED RATS

The objective of the present study was to analyze the role of the arterial chemoreceptors in arterial pressure alterations produced by sinoaortic denervation (SAD) in rats. The mean arterial pressure during 2 h of continuous computerized beat-to-beat recordings was higher after aortic denervation (AD; 130 +/- 2 and 124 +/- 3 mmHg, respectively), lower after sinus denervation (SD; 101 +/- 1 and 101 +/- 3 mmHg), and remained unaltered after SAD (121 +/- 3 and 108 +/- 2 mmHg) 1 and 20 days after denervation compared with control rats (114 +/- 1 mmHg). Hypotensive effect of SD was confirmed when arterial pressure was recorded in the same animal before and after SD (from 112 +/- 2 to 103 +/- 2 mmHg). A similar effect was observed after isolated carotid body artery (CBA) ligation (from 114 +/- 3 to 104 +/- 3 mmHg). Furthermore, CBA ligation attenuated by 13% the hypertension after AD (from 136 +/- 2 to 118 +/- 3 mmHg). Bradycardic response to phenylephrine and arterial pressure variability were markedly altered by SAD and AD but remained normal after SD. In contrast, the chemoreflex (intravenous KCN) was abolished after SAD, SD, and CBA ligation but was preserved after AD. These data suggest that the arterial pressure alteration produced by SAD in rats represents the net effect of the abolition of inhibitory (baroreceptor deafferentation) and excitatory (chemoreceptor deafferentation) influences on the arterial pressure.