Search results for "Adrenergic"

Functional characterization of α1 -adrenoceptor subtypes in vascular tissues using different experimental approaches:a comparative study

2003

The α1-adrenergic responses of rat aorta and tail artery have been analysed measuring the contractility and the inositol phosphate (IP) formation induced by noradrenaline. Three antagonists, prazosin, 5-methylurapidil (α1A selective) and BMY 7378 (α1D selective) have been used in different experimental procedures. Noradrenaline possesses a greater potency inducing contraction and IP accumulation in aorta (pEC50-contraction=7.32±0.04; pEC50-IPs=6.03±0.08) than in the tail artery (pEC50-contraction=5.71±0.07; pEC50-IPs=5.51±0.10). Although the maximum contraction was similar in both tissues (Emax-tail=619.1±55.6 mg; Emax-aorta-698.2±40.8 mg), there were marked differences in the ability of th…

Number and functionality of beta-adrenergic receptors in the mouse lymphocytic P388 leukemia as a doxorubicin-sensitive and -resistant variant.

1992

A comparison of the antihypertensive action of propranolol and the optical isomers of N-isopropyl-p-nitrophenylethanolamine (INPEA)

1969

In hypertensive patients, the effect of propranolol and of the optical isomers of N-isopropyl-p-nitrophenylethanolamine (INPEA) on blood pressure was studied. Single oral doses of 40 mg propranolol, 700 mg (−)-INPEA and 700 mg (+)-INPEA decreased supine systolic as well as standing systolic and diastolic blood pressure. Single intravenous doses of 75 mg (−)-INPEA and 75 mg (+)-INPEA lowered supine systolic and diastolic blood pressure. The antihypertensive action of the beta adrenergic blocking levorotatory isomer of INPEA and of the dextrorotatory isomer, which is devoid of beta adrenergic blocking activity, did not differ. It is concluded from these results that the antihypertensive actio…

Die Konzentration von Noradrenalin und Adrenalin in den einzelnen Abschnitten des Herzens

1959

1. A method for the assay of noradrenaline and adrenaline in small pieces of heart tissue is described. The amines were extracted with acid ethanol and separated by paper chromatography. The regions containing the amines were eluted and the amount of amines in the eluates was determined by bioassay. Noradrenaline was assayed on the blood pressure of the pithed rat. Adrenaline was assayed on the isolated atropinized rat's uterus stimulated with oxytocin. 2. The identity of the substances tested by bioassay with noradrenaline and adrenaline was confirmed by a number of chemical and pharmacological tests. 3. The concentration of catechol amines in different parts of the heart was studied in ca…

Die Hemmbarkeit der inhibitorischen Adrenalinbzw. Noradrenalinwirkung durch Adrenolytika

1958

Dibenamine, dihydroergotamine, regitin and priscol were found to antagonize specifically the inhibitory action of adrenaline and noradrenaline on the electrically stimulated isolated ileum of the guinea-pig. The antagonistic action of dibenamine was irreversible.

Modifications induced in the renin-angiotensin-aldo-sterone system of rats by alpha-blocking drugs.

1978

Summary The data reported in the present paper refer to quantitative variations of plasma renin activity and plasma aldosterone levels after administration of alpha-blocking agents, i.e. phentolamine, phenoxybenzamine and gihydroergotoxin derivatives, either to rats kept on a standard diet with water ad libitum or to rats receiving distilled water load, the latter treatment causing an increase of both plasma renin activity and plasma aldosterone levels if compared to control values. No strict correlation between (a) drug-induced modifications of plasma renin activity and plasma aldosterone levels and (b) blood pressure drop caused by the same drugs was shown to occur under either experiment…

Zur Wirkung von Oxytocin auf einen autorhythmischen glatten Gefässmuskel

1972

The influence of oxytocine on the spontaneously contractile portal vein of the rat has been investigated. This octapeptide decreases the active tension and abolished it completely at a concentration of 5×10−7g/ml. The effect is not caused by an adrenergic mechanism but by a direct action on the smooth muscle cell.

The α1B-adrenoceptor subtype mediates adrenergic vasoconstriction in mouse retinal arterioles with damaged endothelium

2014

Background and Purpose The α1-adrenoceptor family plays a critical role in regulating ocular perfusion by mediating responses to catecholamines. The purpose of the present study was to determine the contribution of individual α1-adrenoceptor subtypes to adrenergic vasoconstriction of retinal arterioles using gene-targeted mice deficient in one of the three adrenoceptor subtypes (α1A-AR−/−, α1B-AR−/− and α1D-AR−/− respectively). Experimental Approach Using real-time PCR, mRNA expression for individual α1-adrenoceptor subtypes was determined in murine retinal arterioles. To assess the functional relevance of the three α1-adrenoceptor subtypes for mediating vascular responses, retinal vascular…

Adrenoceptor-mediated changes of excitation and contraction in isolated heart muscle preparations.

1989

The inotropic effects of sympathetic stimulation on the heart are mainly ascribed to the activation of beta-adrenoceptors. However, several findings suggest that alpha-adrenoceptors also may help mediate the inotropic response to catecholamines under certain conditions. The onset of the positive inotropic effect mediated by beta-adrenoceptors occurs within seconds and is associated with a faster rate of relaxation. Both beta 1- and beta 2-adrenoceptors are stimulatorily coupled to the enzyme adenylate cyclase, thereby leading to the generation of cyclic AMP. Cyclic AMP increases the slow inward calcium current and enhances the uptake of calcium into the sarcoplasmic reticulum. GTP-binding p…

Dehydration of detomidine hydrochloride monohydrate

2010

The thermodynamic stability of detomidine hydrochloride monohydrate has been evaluated on the basis of phase transition kinetics in solid state. A method free of empirical models was used for the treatment of kinetic data, and compared to several known solid state kinetic data processing methods. Phase transitions were monitored by powder X-ray diffraction (PXRD) and thermal analysis. Full PXRD profiles were used for determining the phase content instead of single reflex intensity measurements, in order to minimize the influence of particle texture. We compared the applicability of isothermal and nonisothermal methods to our investigation of detomidine hydrochlorine monohydrate dehydration.