In the driven isolated left atrium of the rabbit theophylline shortened relaxation time in a similar manner to isoprenaline and histamine. 2 Phenylephrine lengthened relaxation time in a similar manner to calcium. 3 Theophylline caused phenylephrine to shorten relaxation time, which was inhibited by a beta-adrenoceptor blocking drug, but theophylline did not potentiate the effect of phenylephri...

The relaxation of phenylephrine-contracted blood vessels by acetylcholine, nitroprusside, or atrial natriuretic factor has been linked to elevations in cyclic guanosine 3',5'-monophosphate (cGMP). Also, 8-bromo-cGMP can induce vascular relaxation in isolated vascular smooth muscle contracted with phenylephrine. We determined whether these cGMP-dependent vasodilators could relax isolated rat aor...

PURPOSE To determine the mydriatic regimen that provides optimal dilation of the pupil with minimal systemic side effects for screening of retinopathy of prematurity. METHODS This cross-sectional, randomized, double-masked clinical trial compared cyclopentolate 1% + phenylephrine 2.5%, tropicamide 1% + phenylephrine 2.5%, and a prepared combination of cyclopentolate 0.2% with phenylephrine 1%...

To determine dose-dependent cardiovascular effects of dobutamine and phenylephrine during anesthesia in horses, increasing doses of dobutamine and phenylephrine were infused to 6 healthy Thoroughbred horses. Anesthesia was induced with xylazine, guaifenesin and thiopental and maintained with sevoflurane at 2.8% of end-tidal concentration in all horses. The horses were positioned in right latera...

The use of phenylephrine has been well described as a potential cause of morbidity and mortality. A thorough literature review of phenylephrine use is presented in this article. The use of ketamine and epinephrine with phenylephrine can precipitate an even more potentially lethal and catastrophic syndrome. We present the case of a 21-year-old man with Hodgkin's lymphoma and lupus who experience...

The effect of cal-adrenoceptor stimulation on the delayed rectifier K' current (IK) was examined in isolated guinea pig ventricular cells by use of the patch-clamp method. 'K was evoked by a 3-second depolarizing pulse from a holding potential of -30 mV in a Na+and K'-free solution containing 3 ,uM nifedipine. Phenylephrine (30 ,uM) in the presence of propranolol (1 ELM) produced an increase in...

BACKGROUND Spinal anesthesia is an accepted technique in elective cesarean sections. However, hypotension, resulted from sympathectomy is a common problem, especially in pregnant women. Prevention of this complication by sympathomimetic agents is of potential clinical significance. The aim of this study is to compare the effect of prophylactic infusion of Phenylephrine versus Ephedrine in the p...

Phenylephrine is generally regarded as a "pure" alpha(1)-agonist. However, after treatment of the forearm with the alpha-adrenergic-blocking drug phentolamine, brachial artery infusion of phenylephrine can cause transient forearm vasodilation. To determine whether this response was beta-receptor mediated, phenylephrine, phentolamine, and propranolol were infused into the brachial arteries of si...

1. Ngan Kee WD, Khaw KS, Tan PE, Ng FF, Karmakar MK: Placental transfer and fetal metabolic effects of phenylephrine and ephedrine during spinal anesthesia for cesarean delivery. ANESTHESIOLOGY 2009; 111:506 –12 2. Dyer RA, Reed AR, Van Dyk D, Arcache MJ, Hodges O, Lombard CJ, Greenwood J, James MF: Hemodynamic effects of ephedrine, phenylephrine, and the coadministration of phenylephrine with ...