This study was designed to determine baroreflex control of heart rate (HR) to hypotensive and hypertensive stimuli during the early follicular (EF), preovulation (PreOV), and midluteal (ML) phases of the menstrual cycle and to test the hypothesis that cardiovagal reflex responses to hypertensive stimuli would be altered depending on the plasma estradiol levels in healthy women. In addition, these results were compared with those of male volunteers. Fifteen healthy women with regular menstrual cycles and thirteen male volunteers were recruited. Cardiovagal baroreflex sensitivity was defined as the slope of the linear portion relating R-R interval and systolic blood pressure triggered by bolus injections of nitroprusside and phenylephrine, from the overshoot phase of the Valsalva maneuver, and during spontaneous fluctuations. Three measurements were averaged in each test as a representative at each phase, and the order of phases was counterbalanced. Baroreflex sensitivities by the phenylephrine pressor test and Valsalva maneuver during the PreOV phase were significantly greater than those during the EF and ML phases but were similar to those of men. Depressor test sensitivities by nitroprusside and down-sequence spontaneous cardiac baroreflex sensitivity during the EF phase were significantly greater than those of the ML phase and of men. Significant correlations were observed between plasma estradiol concentrations and baroreflex sensitivities assessed by phenylephrine and the Valsalva maneuver. Our results indicate that baroreflex control of HR is altered during the regular menstrual cycle, and estradiol appears to exert cardiovagal modulation in healthy women.

We conclude that heart rate responses to both lowering and elevating blood pressure were depressed by propofol anaesthesia, and 60 min was required for their full recovery after discontinuation of propofol infusion.

Simvastatin treatment can attenuate hindlimb motor dysfunction and histopathological changes in spinal cord ischemia/reperfusion injury in rats.

These data show that ultrashort-acting selective beta(1)-adrenoreceptor antagonists can reduce neurological injury in a rat model of spinal cord ischemia-reperfusion.

Sevoflurane depresses cardio-vagal baroreflex gain (ability of vagally mediated R-R interval response to arterial blood pressure change). We examined the effects of sevoflurane anesthesia on maximum buffering capacity of vagally mediated hemodynamic control (baroreflex range) by examining the entire stimulus-response baroreflex relation. Electrocardiogram and invasive arterial blood pressure were monitored in 11 healthy volunteers. Carotid-cardiac baroreflex responses were elicited by increasing neck chamber pressure (external pressure applied over the bilateral carotid sinuses) to 40 mm Hg for 5 heartbeats followed by decreasing chamber pressure by successive 15-mm Hg R-wave triggered decrements to -65 mm Hg during held expiration. R-R intervals were plotted as functions of preceding carotid distending pressure. Range, maximum gain, and operational point (relative position of the resting set point within the entire baroreflex response curve) were determined at conscious baseline, during 2% (end-tidal) sevoflurane anesthesia, without and with phenylephrine infusion to maintain conscious arterial blood pressure, and at 30, 60, 120, and 180 min after emergence from anesthesia. Sevoflurane anesthesia significantly depressed maximum gain (from 3.84 +/- 0.99 to 1.04 +/- 0.40 ms/mm Hg [mean +/- sd]; P < 0.001) and range (from 207 +/- 43 to 52 +/- 19 ms; P < 0.001) of the reflex relation, both of which recovered at 120 and 180 min after emergence. Phenylephrine infusion only partially restored these variables. The operational point was unchanged throughout the study. Our results indicate that maximum cardio-vagal compensatory response to buffer hemodynamic perturbation is depressed during sevoflurane anesthesia. Sevoflurane-induced hypotension, which produced vagal withdrawal, did not play an important role in depressing cardio-vagal reflex function.