Effect of sinoaortic denervation on cardiac output

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Abstract
Cardiac output was measured in 30 rats with neurogenic hypertension of 20, 40, 180, and 360 days duration under light pentobarbital anesthesia. When compared with the values exhibited by 21 normal rats, all the denervated rats (except 4) had normal cardiac outputs, indicating that the major factor responsible for the elevation in blood pressure was an increase in peripheral resistance. Heart rate, blood volume, and hematocrit were also normal in the neurogenic hypertensive rats. For the purpose of comparison the cardiac output was determined in groups of rats with neurogenic, renal, and deoxycorticosterone (DCA) hypertension. The values (ml/min/100 cm2) found in the denervated (14.4), renal (12.4), and DCA (15.0) hypertensive animals were not significantly different from those exhibited by normal rats (15.4). The blood volume of the rats with DCA hypertension was elevated. The results indicate that the hypertension produced in the rat by sinoaortic denervation, as well as that caused by DCA injection or renal artery constriction, is due to increased peripheral resistance rather than to elevation of cardiac output.