Effects of fentanyl on carotid sinus baroreflex control of circulation in rabbits

Abstract

The effects of intravenous administration of fentanyl on carotid sinus baroreflex control of hemodynamics were investigated 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 micrograms/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 0.104 +/- 0.005 mmHg.min-1.ml-1 and augmented the HR response from 31 +/- 2 to 47 +/- 3 beats/min in the conscious state and at 15 micrograms/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 micrograms/kg of fentanyl, respectively. We suggest that these dissociated hemodynamic responses reflect the vagotonic and sympatholytic effects of fentanyl on the baroreflex pathways.

Effects of diazepam on the carotid sinus baroreflex control of circulation in rabbits

“…The administration of diazepam caused minimum blood gas changes. However, blood gas changes of the same extent induced by the inhalation of hypercarbic and hypoxic gas did not alter haemodynamic response to BCO (Ohsumi et al 1989). Furthermore, we examined the possible influence of the vehicle on haemodynamics and the arterial baroreflex.…”

“…The injection took 15-20 s. The BCO procedure was done 3 min after each injection of diazepam. The BCO procedure is described in detail elsewhere (Ohsumi et al 1989). In the BCO procedure, the bilateral occluding cuffs were inflated simultaneously for I min with the amount of saline previously determined for a complete occlusion of carotid arteries.…”

Comparison of the role of endothelin, vasopressin and angiotensin in arterial pressure regulation during sevoflurane anaesthesia in dogs

“…To assess whether potential differences in arterial pressure between groups are modi®ed by the arterial barore¯ex, we measured the sensitivity of the carotid barore¯ex sensitivity (BRS) as described previously. 13 Both carotid arteries were occluded simultaneously for 45 s with self-made external cuff occluders, resulting in a decrease in CSP and an increase in heart rate. BRS was calculated as the quotient of changes in RR interval (ms) and CSP (BRS=DRR/DCSP).…”

Etiology, Diagnosis, and Pharmacologic Treatment of Pediatric Pulmonary Hypertension

“…[55] As the cardiac output increases, so does recruitment of small resistance pulmonary arteries. The resulting increase in the total cross-sectional area of pulmonary blood flow reduces the PVR.…”