Search results for "Ephrin"

Differential electrophysiologic and inotropic effects of phenylephrine in atrial and ventricular heart muscle preparations from rats.

1991

Stimulation of alpha 1-adrenoceptors evokes a different pattern of inotropic responses in atrial and ventricular heart muscle preparations from rats. The inotropic effects are accompanied by different changes in membrane potential. In an attempt to clarify the question whether or to which extent these events are causally related, the effects of phenylephrine on force of contraction, transmembrane potential, Ca2+ current (ICa) and K+ currents were comparatively studied in either tissue. In atrial preparations, phenylephrine 10 mumol/l caused an increase in force of contraction, a marked prolongation of the action potential duration and a depolarization of the membrane at rest. In the ventric…

Catecholamine release in human skin--a microdialysis study.

2003

Dermal microdialysis might be a promising tool to investigate properties of sympathetic neurons in the skin as investigation of peripheral noradrenergic neurons in humans usually relies on highly variable vasoconstrictor reflexes or on indirect measurements like skin temperature recordings. To evaluate this technique, 21 experiments were performed in 15 healthy subjects with four intracutaneous microdialysis fibers (diameter, 200 microm; cutoff, 5 kDa) at hands or feet. After 60 min, saline perfusion tyramine at concentrations of 0.195 to 200 microg/ml was applied for 15 min followed by a 15-min saline perfusion again. Catecholamine concentrations were detected through high-performance liqu…

Plasma noradrenaline and the pressor action of exogenous noradrenaline in normotensive subjects and patients with essential hypertension.

1978

1. An inverse relationship was found between plasma noradrenaline and reactivity to exogenous noradrenaline in normotensive subjects. 2. The relationship between plasma noradrenaline and reactivity was disturbed in age-matched patients with essential hypertension. 3. A multiple-regression analysis showed a highly significant correlation between adrenergic activity and reactivity to noradrenaline and the mean arterial blood pressure level (r = 0·91). The results suggest that adrenergic activity and pressor response to noradrenaline combined are important determinants of arterial blood pressure. 4. An inverse relationship could also be demonstrated between plasma renin activity and reactivity…

Glycyrrhetinic Acid Reverses the Lipopolysaccharide-Induced Hypocontractility to Noradrenaline in Rat Aorta: Implications to Septic Shock

2014

Abstract.: Septic shock and associated vascular hyporeactivity to vasoconstrictor agonists remain a major problem of critical care medicine. Here we report that glycyrrhetinic acid (GA), the active component of licorice, effectively restores vascular contractility in the model of lipopolysaccharide (LPS)-treated rat aorta. GA was as effective as the NO synthase inhibitor NG-nitroarginine methylester. GA did not affect the vascular NO levels (measured by EPR spin trapping) and relaxations to l-arginine in LPS-treated rings as well as relaxation to S-nitroso-Nacetylpenicillamine in control rings. Thus, GA may represent an interesting alternative to NO synthase inhibitors in sepsis-associated …

Noradrenalin- und Adrenalingehalt des Rattenherzens bei experimenteller Niereninsuffizienz

1960

Norepinephrine transporter gene polymorphism is not associated with susceptibility to alcohol dependence

2002

Abnormalities in monoamine neurotransmission have been implicated in the pathogenesis of alcoholism, mood disorders and schizophrenia. Murine norepinephrine transporter gene (NET) has been mapped to a region on chromosome 8 where a quantitative trait locus for ethanol sensitivity. Therefore we tested whether norepinephrine transporter (NET) gene variants confer susceptibility to either alcohol dependence or severe alcohol withdrawal symptoms. There is a highly polymorphic silent G1287A mutation in the NET gene. In our study 157 alcoholics and 185 healthy unrelated matched control subjects were analyzed for a silent G1287A mutation. No significant differences in allele and genotype distribut…

Description of the response of a new multi-parametric brain sensor to physiological and pathophysiological challenges in the cortex of juvenile pigs

2014

AIM Monitoring of intracranial pressure (ICP), local cerebral blood flow (CBF) and oxygen is part of modern intensive critical care medicine. Preclinical evaluation of newly developed catheters that should monitor several parameters simultaneously is reported poorly in the literature. The goal of our study was (1) to evaluate a new multi-parametric sensor in brain tissue and (2) to establish a testing protocol using pathophysiological challenges that target measured parameters of the sensor and autoregulatory boundaries and could be used as preclinical standard protocol in future studies. MATERIAL AND METHODS We describe data from 12 new multi-parametric brain sensors (MPBS) that were impla…

Evidence that depletion of internal calcium stores sensitive to noradrenaline elicits a contractile response dependent on extracellular calcium in ra…

1993

1. Noradrenaline 1 microM induced a contractile response in rat isolated aorta in the presence or in the absence of extracellular Ca2+ with depletion of intracellular Ca2+ stores. Thereafter, during incubation in the presence of Ca2+, an increase in the resting tone was observed. Such a contractile response did not occur after exposure to caffeine or 5-hydroxytryptamine. 2. This increase in tension was inhibited in a concentration-dependent manner by alpha-adrenoceptor antagonists (prazosin, phentolamine and yohimbine), the non-specific relaxing compound, papaverine and by the Ca(2+)-entry blocker, nifedipine. Therefore, this contractile process is related to depletion of Ca2+ stores sensit…

Nitric Oxide Opposes Myogenic Pressure Responses Predominantly in Large Arterioles In Vivo

1998

Abstract —A myogenic vasoconstriction may amplify the effects of circulating vasoconstrictors. In cremaster arterioles, the contribution of a myogenic component to the constriction on intravenous infusion of norepinephrine (NE) or angiotensin II (Ang II) was studied. Second, the role of endothelium-derived nitric oxide (NO) in the control of these myogenic constrictions and its site of action in the resistance vascular bed was investigated. In 30 anesthetized (pentobarbital) hamsters, the cremaster was prepared for intravital microscopy, and a pneumatic vessel occluder was placed around the aorta to vary blood pressure in the hindquarter of the animal. Intravenous infusion of NE (0.5 nmol/…

Effect of Phenylephrine on the Accommodative System

2016

Accommodation is controlled by the action of the ciliary muscle and mediated primarily by parasympathetic input through postganglionic fibers that originate from neurons in the ciliary and pterygopalatine ganglia. During accommodation the pupil constricts to increase the depth of focus of the eye and improve retinal image quality. Researchers have traditionally faced the challenge of measuring the accommodative properties of the eye through a small pupil and thus have relied on pharmacological agents to dilate the pupil. Achieving pupil dilation (mydriasis) without affecting the accommodative ability of the eye (cycloplegia) could be useful in many clinical and research contexts. Phenylephr…