BACKGROUND The authors have previously observed an apparent association between rostral spread of spinal anesthesia and choice of intravenous vasopressor given to maintain maternal systolic arterial pressure during cesarean delivery. This study tested the hypothesis that an intravenous infusion of phenylephrine can reduce rostral spread of spinal anesthesia in pregnancy, compared with ephedrine...

We investigated the role of interleukin-1beta (IL-1beta) and prostaglandins (PG) in the alpha(1)-adrenergic agonist, phenylephrine-induced hypothalamic-pituitary-adrenal axis (HPA) responses under basal and social stress conditions. Male Wistar rats, either control or exposed to crowding stress for 7 days prior to treatment, were used in these experiments. All compounds were injected i.p. Cyclo...

BACKGROUND Hypotension remains a common clinical problem of spinal anesthesia for cesarean delivery and phenylephrine is used as a vasopressor to address this. However, phenylephrine reduces maternal cardiac output (CO) due to reflex bradycardia. Glycopyrrolate is safe for the fetus, and increases heart rate (HR). Using a noninvasive measure of CO, we compared maternal hemodynamic changes betwe...

BACKGROUND AND AIMS Haeme oxygenase could play a role in the pathogenesis of arterial vasodilation in cirrhosis. The aim of this study was to verify the role of haeme oxygenase in the hyporesponsiveness to phenylephrine of small mesenteric arteries in rats with CCl(4) induced cirrhosis, with and without ascites. METHODS Pressurised small resistance mesenteric arteries were challenged with inc...

We investigated whether chronic infusion of phenylephrine could induce structural and functional changes in the kidney of rats with the subsequent development of salt-sensitive hypertension. Rats were infused with phenylephrine (0.15 mmol/kg per day) by minipump, resulting in a moderate increase in systolic blood pressure (BP) (17 to 25 mm Hg) and a marked increase in BP variability as measured...

BACKGROUND The intravenous administration of indigo carmine has been reported to produce transiently increased blood pressure in patients. The goal of this in vitro study was to examine the effect of indigo carmine on phenylephrine-induced contractions in an isolated rat aorta and to determine the associated cellular mechanism with particular focus on the endothelium-derived vasodilators. MET...

Glucose output from perfused livers of 48 h-starved rats was stimulated by phenylephrine (2 microM) when lactate, pyruvate, alanine, glycerol, sorbitol, dihydroxyacetone or fructose were used as gluconeogenic precursors. Phenylephrine-induced increases in glucose output were immediately preceded by a transient efflux of Ca2+ and a sustained increase in oxygen uptake. Phenylephrine decreased the...

The present study assessed whether the baroreflex inhibition elicited by electrical stimulation of the hypothalamic paraventricular nucleus (PVN) involves altered activity in the nucleus of the solitary tract (NTS). Unit recordings were made from 107 neurons in the NTS in anesthetized rabbits. Intravenous phenylephrine was used to induce a pressor response and to activate baroreflexes. Of the n...

Shortly after birth, cardiac myocytes lose the ability to divide, and, in adult animals, heart muscle grows by a process of cellular hypertrophy where each individual cell gets larger. We have previously shown that activated Ras protein can induce markers of the hypertrophic phenotype, including atrial natriuretic factor (ANF) expression and organization of contractile proteins, and that Ras is...

PURPOSE To examine the inhibitory effects of topically instilled bunazosin hydrochloride (bunazosin), a selective alpha1-adrenoceptor antagonist, on the retinal artery constrictions induced by intravitreous phenylephrine hydrochloride (phenylephrine) and endothelin (ET)-1 in rabbits. METHODS Phenylephrine or ET-1 (20 microL) was injected into the central part of the vitreous in both eyes in p...