Difference in the effect of pancuronium and vecuronium on baroreflex control of heart rate in humans

Abstract

The effects of pancuronium and vecuronium, each in doses of 0.05 and 0.08 mg·kg⁻¹, on the baroreflex control of the heart rate were studied in 40 adult patients of either sex (21 men and 19 women) during stable nitrous oxide-oxygen-fentanyl anesthesia. The blood pressure was elevated by intravenous infusion of phenylephrine (4 μgg·kg⁻¹·min⁻¹) for the pressor test, and lowered by a bolus injection of nitroglycerin (0.3–0.5 mg) for the depressor test. Baroreflex sensitivity was judged from the slope of the regression of the systolic blood pressure on the succeeding R-R intervals on the ECG. There was no significant difference between the baseline blood pressure at which both tests were carried out. Nitrous oxide-oxygen-fentanyl anesthesia alone suppressed the baroreflex sensitivity to a level which was at the lower limit of the physiological and non-anesthetized state. The 0.08 mg·kg⁻¹ dose of pancuronium significantly suppressed the reflex sensitivity in both the pressor and depressor tests. However, the 0.05 mg·kg⁻¹ dose of pancuronium and both doses of vecuronium did not cause any significant change in the test results.