Effects of fentanyl on carotid sinus baroreflex control of circulation in rabbits
Ohsumi, H.; Sakamoto, M.; Yamazaki, T.; Okumura, F.
American Journal of Physiology 256(3 Pt 2): R625-R631
1989
ISSN/ISBN: 0002-9513 PMID: 2493749 Document Number: 335250
The effects of intravenous administration of fentanyl on carotid sinus baroreflex control of hemodynamics were investiatged in chronically instrumented rabbits. Carotid sinus baroreflex was assessed by bilateral carotid occlusion (BCO), and the responses of mean arterial pressure (MAP), heart rate (HR), mean ascending aortic flow (MAF), and total peripheral resistance (TPR) were obtained. Hemodynamic responses to BCO were examined with cumulative doses of 5, 10, and 15 .mu.g/kg of fentanyl. Fentanyl did not affect MAP and TPR but reduced HR and MAF dose dependently. Fentanyl did not attenuate the MAP response to BCO significantly. In contrast, fentanyl significantly attenuated the TPR response from 0.126 .+-. 0.003 to 0.014 .+-. 0.005 mmHg .cntdot. min-1 .cntdot. ml-1 and augmented the HR response from 31 .+-. 2 to 47 .+-. 3 beats/min in the conscious state and at 15 .mu.g/kg of fentanyl, respectively. The administration of atropine after the fentanyl attenuated MAP and HR responses to 79.9 and 27.7% of those of 10 .mu.g/kg of fentanyl, respectivley. We suggest that these dissociated hemodynamic responses reflect the vagotonic and sympatholytic effects of fentanyl on the baroreflex pathways.