The protective effect of phentolamine against cardiac arrhythmias in the rat

Williams, Betty J.; Griffith, William H.; Albrecht, Catherine M.

doi:10.1016/0014-2999(78)90216-9

Cited by 14 publications

(4 citation statements)

References 15 publications

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“…It is unclear, ho'wever, to what extent this electrical property is dependent upon a-adrenoceptors. Stewart et al (1980) concluded that a-adrenoceptors were not involved in the blockade of the fast sodium channel, but Williams, Griffith & Albrecht (1978) reached an opposite conclusion. Corr, Shayman, Kramer & Kipnis (1981) not only invoked aadrenoceptors in the antiarrhythmic action of phentolamine but ascribed its effectiveness in ischaemic hearts to an increased number of a-adrenoceptors in ischaemic compared with normal myocardium.…”

Section: Introductionmentioning

confidence: 99%

A comparison of the electrophysiological actions of phentolamine with those of some other antiarrhythmic drugs on tissues isolated from the rat heart

Northover

1983

British J Pharmacology

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1Glass microelectrodes were used to record transmembrane electrical activity from cells located just beneath the endocardial surface of segments from the atrial and right ventricular free walls of rat hearts during superfusion and electrical stimulation in vitro at 37°C. 2 Availability of the fast sodium channels for current flow was inferred from the maximum rate of rise of membrane potential during phase 0 of the action potential. 3 Phentolamine mesylate (2 to 20 LM) caused a concentration-dependent block of the fast sodium channel. This was reflected in prolongation of the refractory period and slowing of recovery of excitability following the action potential, without significant change in action potential duration or resting membrane potential. 4 Increase in the concentration of KCI in the superfusate from 5 to 10 mm depolarized the muscle and potentiated the blocking action of phentolamine. Both the depolarizing and the phentolaminepotentiating actions of KCI were counteracted by simultaneous elevation of the concentration of CaC12 in the superfusate from 2 to 10 mM. 5 The blocking action of phentolamine was enhanced by increasing the frequency of electrical stimulation in the range 0.01 to 10 Hz. 6 In respect of the properties listed above, lignocaine hydrochloride was similar to phentolamine but was different from quinidine sulphate in that the effects of the latter drug were not potentiated by KCl. 7 Two other ac-adrenoceptor antagonists, prazosin and yohimbine, both displayed actions similar to those shown by phentolamine. Tolazoline was only weakly active and dihydroergotamine (60 pM) was inactive. Dibenamine and phenoxybenzamine, unlike the previously named drugs, caused an irreversible block of the fast sodium channel. These blocking actions of oa-adrenoceptor antagonists were not prevented by simultaneous exposure to the ot-adrenoceptor agonist phenylephrine (1 mm). 8 Muscle from both reserpine pretreated and non-pretreated rats responded indistinguishably to phentolamine.

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Section: Introductionmentioning

confidence: 99%

A comparison of the electrophysiological actions of phentolamine with those of some other antiarrhythmic drugs on tissues isolated from the rat heart

Northover

1983

British J Pharmacology

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“…The effect of alpha-adrenergic receptor blockade in this model is dramatic, with either phentolamine or prazosin reducing mortality from 26% in untreated controls to 2% in drug-treated animals (Corr and Crafford, 1981). Antiarrhythmic effects of phentolamine have also been observed in the guinea pig against arrhythmias induced by reducing coronary flow (Penny and Sheridan, 1982), and against norepinephrine-induced arrhythmias in the anesthetized rat (Williams et al, 1978). Tolazoline and yohimbine were also effective in the latter model (Williams et al, 1978).…”

Section: Alpha-adrenergic Receptor Antagonists As Antiarrhythmic Agentsmentioning

confidence: 98%

“…Antiarrhythmic effects of phentolamine have also been observed in the guinea pig against arrhythmias induced by reducing coronary flow (Penny and Sheridan, 1982), and against norepinephrine-induced arrhythmias in the anesthetized rat (Williams et al, 1978). Tolazoline and yohimbine were also effective in the latter model (Williams et al, 1978). In the dog, phentolamine has been shown to produce beneficial effects against arrhythmias induced by norepinephrine, epinephrine, or nicotine (Leimdorfer, 1952).…”

Section: Alpha-adrenergic Receptor Antagonists As Antiarrhythmic Agentsmentioning

confidence: 99%

The alpha-1 Adrenergic Receptors

Ruffolo¹

1987

The Receptors

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All rights reservedNo part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise without written permission from the Publisher.Preface vii ology will allow alpha-l adrenergic receptors to be isolated and purified and their amino acid sequence to be identified. This will ultimately allow for the systematic subclassification of alpha-l adrenergic receptors and for their differential regulation to be studied in greater detail. These new advances are likely to take place within the next five years, and it is our intent for this review of alpha-l adrenergic receptor pharmacology to provide an accurate summary of the current state of knowledge relating to alpha-l adrenergic receptors, which we hope will serve as a foundation upon which to build a broader base of knowledge in the future.

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“…1974;Govier, 1968;Iversen ct al.. 1972;Parr and Urquilla. 1972;Potter et al, 1971;Williams et al, 1978]. This explains the ability of these drugs to produce tachycardia.…”

Section: Preferential Medical Uses Of Trazodonementioning

confidence: 99%

Trazodone, a New Avenue in the Treatment of Depression

Silvestrini¹,

Valeri²

1984

Psychopathology

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Pharmacological and biochemical data on trazodone are reviewed in order to compare this drug to imipramine and other tricyclics both from the point of view of the mechanism of action and preferential clinical indications. Trazodone tends to inhibit biochemical and pharmacological functions depending on the catecholaminergic system, whereas imipramine has a potentiating activity. However, both these drugs decrease the density of β-receptors following repeated administrations. Trazodone and imipramine have similar effects on the serotoninergic system. The two drugs also share an antinociceptive activity. It is stressed that this activity has been of critical importance in the discovery of trazodone. In fact, the development of this drug was based on the working hypothesis that a disturbance in the perception of unpleasant experience has a role in the pathogenesis of depression. Some medical implications of the α-blocking activity of trazodone are discussed. Trazodone is preferable to other antidepressant treatment when depression is associated with angle-closure glaucoma, cardiovascular disturbances depending on noradrenaline release, tremor, some psychotic conditions and alcoholism.

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The protective effect of phentolamine against cardiac arrhythmias in the rat

Cited by 14 publications

References 15 publications

A comparison of the electrophysiological actions of phentolamine with those of some other antiarrhythmic drugs on tissues isolated from the rat heart

A comparison of the electrophysiological actions of phentolamine with those of some other antiarrhythmic drugs on tissues isolated from the rat heart

The alpha-1 Adrenergic Receptors

Trazodone, a New Avenue in the Treatment of Depression

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