BACKGROUND Spinal anesthesia causes hypotension and bradycardia due to sympathetic nerve block and it is difficult to predict the level of sensory block and the duration of blockade. Recent studies have reported that intravenous phenylephrine can reduce the rostral spread of spinal anesthesia in pregnant women. We think a phenylephrine infusion will be useful for maintaining the baseline blood ...

The effect of phenylephrine, an alpha-agonist, on the Ca movements and the influence of removal of external Na+ on the relaxant activity of phenylephrine were examined in the taenia coli of guinea pigs. Phenylephrine (10(-7)-10(-5)M) caused dose-dependent relaxation of the taenia coli contracted by 20 mM KCl in Locke-Ringer solution. Phenylephrine (10(-5) M) suppressed the spike discharges of t...

OBJECTIVE To determine the effect of changes in autonomic tone induced by phenylephrine infusion on atrial refractoriness and conduction. DESIGN Left and right atrial electrophysiological properties were measured before and after a constant phenylephrine infusion designed to increase sinus cycle length by 25%. SUBJECTS 20 patients, aged 53 (SD 6) years, undergoing electrophysiological study...

Ophthalmic surgeons often apply phenylephrine topically to effect pupillary dilatation. We describe a paediatric patient in whom cardiac arrhythmias, severe hypertension and pulmonary oedema occurred following intraoperative ocular phenylephrine administration. We believe that systemic absorption of the drug was responsible and discuss ways in which this might be reduced when ocular phenylephri...

Whether sympathetic activity influences cerebral blood flow (CBF) and oxygenation remains controversial. The influence of sympathetic activity on CBF and oxygenation was evaluated by the effect of phenylephrine on middle cerebral artery (MCA) mean flow velocity (Vmean) and the near-infrared spectroscopy-derived frontal lobe oxygenation (ScO2) at rest and during exercise. At rest, nine healthy m...

BACKGROUND Phenylephrine and ephedrine are both used to maintain arterial blood pressure during spinal anesthesia for cesarean delivery. Usually, either drug is given alone but several previous studies have described combining the drugs. However, the effect of varying the proportion of vasopressors in such combinations has not been reported. METHODS One-hundred-twenty-five parturients having ...

The vasodilator activity of alpha(1)-adrenoceptor agonists was tested in the rat mesenteric vascular bed (MVB), and the mechanism involved was investigated in cultured endothelial cells isolated from the bovine coronary vascular bed. In preparations preconstricted by U46619, noradrenaline and phenylephrine induced a slight relaxant effect at nanomolar concentrations. This effect was abolished i...

Vasoconstrictive properties of sympathomimetic drugs are the basis of their widespread use as decongestants and possible source of adverse responses. Insufficiently substantiated practice of combining decongestants in some marketed preparations, such are those containing phenylephrine and lerimazoline, may affect the overall contractile activity, and thus their therapeutic utility. This study a...

Changes in reactivity to phenylephrine in aortas isolated from 2-, 6-, and 10-week ethanol-treated rats and their age-matched control and isocaloric rats were investigated. Chronic ethanol consumption enhances the contractile response of endothelium-intact and -denuded rat aortic rings to phenylephrine, a response that is time-independent. Pretreatment with indomethacin reduced E(max) for pheny...