Alpha-adrenoceptors in the myocardium: incidence and functional significance
Alpha-adrenoceptors mediating positive inotropic effects are well established in the heart of various species including human heart. The mechanism by which alpha-adrenoceptor stimulation increases force of contraction is not known. cAMP is unlikely to be involved as a mediator. Evidence has been presented that an increase in magnitude and duration of the slow Ca++ inward current may be partly responsible for the positive inotropic effect. In addition, stimulation of alpha-adrenoceptors may increase Ca++ sensitivity of the contractile proteins. Stimulation of alpha-adrenoceptors by endogenous catecholamines may serve as a reserve mechanism under various conditions of impaired beta-adrenergic influence, e.g. hypothyroidism, bradycardia or ischemia. Furthermore, alpha-adrenoceptors may be involved in the genesis of reperfusion arrhythmias in ischemic heart.
alpha-Adrenoceptors in the ventricular myocardium: clonidine, naphazoline and methoxamine as partial alpha-agonists exerting a competitive dualism in action to phenylephrine
alpha-Adrenoceptors mediating positive inotropic effects on the ventricular myocardium: some aspects of structure-activity relationship of sympathomimetic amines
Alpha-adrenoceptor-mediated restoration of calcium-dependent potential in the partially depolarized rabbit papillary muscle
Qualitative differences between beta-adrenergic and alpha-adrenergic inotropic effects in rat heart muscle
Characterization of adrenoceptors mediating positive inotropic responses in the ventricular myocardium of the dog
Thyroxine and propylthiouracil effects on alpha- and beta-adrenergic receptor number, ATPase activities, and sialic acid content of rat cardiac membrane vesicles
The time course of the effects of beta- and alpha-adrenoceptor stimulation by isoprenaline and methoxamine on the contractile force and cAMP level of the isolated rabbit papillary muscle
Positive inotropic effect without cyclic AMP elevation after alpha-adrenergic stimulation of perfused hearts from hypothyroid rats
Relationship between the level of cAMP and the contractile force under stimulation of alpha- and beta-adrenoceptors by phenylephrine in the isolated rabbit papillary muscle
Comparison of the mechanisms underlying the positive inotropic actions of dopamine, adrenaline and isoprenaline on the isolated rabbit papillary muscle
Lack of correlation between the positive inotropic effect evoked by alpha-adrenoceptor stimulation and the levels of cyclic AMP and/or cyclic GMP in the isolated ventricle strip of the rabbit
No evidence for involvement of dopaminergic receptors in the positive inotropic action of dopamine on the isolated rabbit papillary muscle
Demonstration in human atrial preparations of alpha-adrenoceptors mediating positive inotropic effects
Influence of thyroid hormone on the positive inotropic effects mediated by alpha- and beta-adrenoceptors in isolated guinea pig atria and rabbit papillary muscles
Reduction by adenosine of the isoproterenol-induced increase in cyclic adenosine 3',5'-monophosphate formation and glycogen phosphorylase activity in rat heart muscle
Biochemical evidence for presynaptic and postsynaptic alpha-adrenoceptors in rat heart membranes: positive homotropic cooperativity of presynaptic binding
Changes of adrenoceptor-mediated responses in the pithed rat during propylthiouracil-induced hypothyroidism
Differentiation by cholinergic stimulation of positive inotropic actions mediated via alpha- and beta-adrenoceptors in the rabbit heart
alpha 1-Adrenergic receptors in guinea pig myocardium: identification by binding of a new radioligand, (3H)-prazosin
Influence of temperature on the sensitivity of the adrenoceptors in the isolated atria of guinea pigs and rats
Frequency-dependence of the positive inotropic effect of methoxamine and naphazoline mediated by alpha-Adrenoceptors in the isolated rabbit papillary muscle
Characterization of the adrenoceptors mediating the positive ino- and chronotropic effect of phenylephrine on isolated atria from guinea pigs and rabbits by means of adrenolytic drugs
Positive inotropic effects of phenylephrine in the isolated rabbit papillary muscle mediated both by alpha- and beta-adrenoceptors
Stimulation by phenylephrine of adrenergic alpha- and beta-receptors in the isolated perfused rabbit heart
Localization of beta adrenergic receptors, and effects of noradrenaline and cyclic nucleotides on action potentials, ionic currents and tension in mammalian cardiac muscle
Effect of digoxin on the heart in normal subjects: influence of isometric exercise and autonomic blockade: a noninvasive study
The effects of nitroglycerin on exercise-induced regional myocardial contractile dysfunction are not diminished by pretreatment with dihydroergotamine
Pharmacological studies on a new antihypertensive agent, S-2150, a benzothiazepine derivative: 1. Antinecrotic and antiarrhythmic effects in reperfused rat hearts
Influence of the calcium-sensitizer UDCG-115 on hemodynamics and myocardial energetics in patients with idiopathic dilated cardiomyopathy. Comparison with nitroprusside
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