Mechanism of Increased Susceptibility to Fibrillation of the Hypothermic Mammalian Heart in Situ

Szekeres, L.; Méhes, J.; Papp, Julius Gy.

doi:10.1111/j.1476-5381.1961.tb01277.x

Cited by 7 publications

(2 citation statements)

References 15 publications

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“…Arrhythmias were at no time observed in any dog during UK14275 administration. Adrenergic mechanisms are believed however to play an important role in arrhythmogenesis under conditions such as ischaemia (Ceremuzynski, Staszewska-Barczak & Herbacynska-Cedro, 1969;Jewitt et al, 1969), hypothermia (Szekeres, Mehes & Papp, 1961) excessive neurogenic stimulation (Han,Garcia de Jalon & Moe, 1964) or digitalis toxicity and UK14275 might therefore produce similar responses under such conditions. No electrophysiological effect of UK14275 not attributable to an adrenergic mechanism was noted in this study.…”

Section: Discussionmentioning

confidence: 99%

Electrophysiological and haemodynamic effects of a new inotropic agent (UK 14275) in the dog

Russell

Smith

Oliver

1979

Clin Exp Pharmacol Physiol

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1. Electrophysiological and haemodynamic effects after intravenous administration of a new inotropic agent (UK14275) have been examined in open-chest dogs under pentobarbitone anaesthesia. 2. UK14275 produced slight shortening of QT interval, ventricular functional refractory period and atrio-ventricular conduction time but did not affect action potential duration or endocardial-epicardial conduction time. 3. Cardiac output and left ventricular dP/dt increased, and systemic vascular resistance fell. 4. An end-systolic pressure gradient developed between left ventricle and aorta attributable to left ventricular cavity obliteration.

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Section: Discussionmentioning

confidence: 99%

Electrophysiological and haemodynamic effects of a new inotropic agent (UK 14275) in the dog

Russell

Smith

Oliver

1979

Clin Exp Pharmacol Physiol

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“…On the other hand, recent evidence has indicated that a-receptor blockade does contri(bute to protection against arrhythmias induced by oualbain (Barrett & Cullum, 1968;Raper & Wale, 1968;Dohadwalla, Freedberg & Vaughan Williams, 1969) or by acetylcholine (Hashimoto, Chiba, Tanaka, Hirata & Suzuki, 1968). Surgical removal of cardiac sympathetic nerves raises the fibrillation threshold in the cat (Szekeres, Mehes & Papp, 1961;Papp & Szekeres, 1967), and it is possilble that the anti-arrhythmic action of bretylium could be due to depression of activity in sympathetic nerves. Leveque (1965) observed that bretylium did not exhilbit maximum anti-arrhythmic effectiveness until after 4 hr.…”

Section: Discussionmentioning

confidence: 99%

The effect of bretylium on intracellular cardiac action potentials in relation to its anti‐arrhythmic and local anaesthetic activity

Papp

Williams

1969

British J Pharmacology

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. The initial effect of bretylium tosylate on isolated rabbit atria was to increase conduction velocity, contraction heights, spontaneous frequency and maximum driven frequency, and to reduce electrical threshold. At concentrations of 200 mg/l. or less, these were the only effects, and were consistent with the known sympathomimetic actions of bretylium. . At extremely high concentrations, 1,200 and 2,400 mg/l., the initial actions were succeeded by weak quinidine‐like effects; reduced conduction velocity, spontaneous and maximum driven frequencies, and rate of rise of action potential. The electrical threshold was raised, but contraction heights were not reduced. . The local anaesthetic activity of bretylium, measured by reductions in the frog nerve action potential, was 1/90 that of procaine and 1/300 that of propranolol, on a molar basis. . Acute pretreatment with bretylium, 20 mg/kg intravenously, significantly increased the amount of infused ouabain required before the appearance of the first signs of atrial arrhythmia in anaesthetized guinea‐pigs, but did not prevent ventricular arrhythmias. . Pretreatment with bretylium 30 mg/kg subcutaneously 24 hr, and again 4 hr before ouabain infusion, increased the dose of ouabain inducing atrial irregularity and slightly but significantly reduced the incidence of ventricular fibrillation.

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Intracardiac electric stimulation in conscious rabbits

Thormählen¹,

Rohte²

1981

Naunyn-Schmiedeberg's Arch. Pharmacol.

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Cardiac arrhythmics were induced in conscious rabbits by intracardiac electric stimulation. The arrhythmic threshold remained constant for a period of more than 6 months. The antiarrhythmic drugs ajmaline, prajmalium, disopyramide, quinidine, lidocaine, propranolol and verapamil, given i.v. or orally, were screened for their threshold-raising potency. Particularly the membrane-stabilizing antiarrhythmics showed significant effects. The model may constitute a useful screen for such drugs in the conscious animal.

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Mechanism of Increased Susceptibility to Fibrillation of the Hypothermic Mammalian Heart in Situ

Cited by 7 publications

References 15 publications

Electrophysiological and haemodynamic effects of a new inotropic agent (UK 14275) in the dog

Electrophysiological and haemodynamic effects of a new inotropic agent (UK 14275) in the dog

The effect of bretylium on intracellular cardiac action potentials in relation to its anti‐arrhythmic and local anaesthetic activity

Intracardiac electric stimulation in conscious rabbits

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