Parachloromercuribenzoate on action potentials of Purkinje and ventricular fibers of hog heart

Kleinfeld, Morris; Stein, Edward; Murphy, Bernard

doi:10.1152/ajplegacy.1964.206.5.975

Cited by 6 publications

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“…It is unlikely that parachloromercuribenzoate has any single specific site of action on myocardium metabolism; recent studies of its effect on isolated cardiac tissue (20) suggested and myocardial contractility in hearts deprived of autonomic activity.…”

Section: Discussionmentioning

confidence: 99%

Effects of Hypoxia and Metabolic Inhibitors on the Intrinsic Heart Rate and Myocardial Contractility in Dogs

Jose

Stitt

1969

Circulation Research

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Previous studies have shown that after autonomic blockade by propranolol and atropine, the intrinsic rate and contractile function of the heart were related in patients with myocardial failure. In this study the intrinsic rate and ventricular contractile force were measured in dogs during acute heart failure produced by agents which impair myocardial energy synthesis, to see whether these conditions reproduced the relationship found in naturally occurring myocardial disease in man. Anesthetized dogs, after propranolol and atropine, were either ventilated with 6% oxygen or given sodium cyanide, parachloromercuribenzoate, or dinitrophenol by intravenous infusion. Hypoxia and cyanide initially increased and then depressed both rate and contraction. Parachloromercuribenzoate depressed both. Dinitrophenol depressed only contraction. During hypoxia, cyanide, and parachloromercuribenzoate the percent changes in contractile force and intrinsic rate were linearly related (r=0.87) with slopes of 3.2, 2.7, and 3.3, respectively. These results together with previous data during pentobarbital and aminophylline were consistent with a single linear relationship between rate and contractility (r = 0.89, slope 3.2). This resembled closely the relationship found previously in man. It is suggested that in both situations, this relationship may be determined by a dependence of rate and contractility on similar limited sources of energy.ADDITIONAL KEY WORDS denervated heart myocardial failure propranolol atropine myccardial energy synthesis• In a previous study in man, we used propranolol and atropine to study the intrinsic functional properties of the myocardium at different stages of myocardial disease (1, la). It was found that after autonomic blockade by these drugs, the heart rate became fixed to most stimuli, at a value which varied in different individuals inversely with the severity of the myocardial disease. This value, which we named the intrinsic heart rate, was directly

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Section: Discussionmentioning

confidence: 99%

Effects of Hypoxia and Metabolic Inhibitors on the Intrinsic Heart Rate and Myocardial Contractility in Dogs

Jose

Stitt

1969

Circulation Research

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“…On the other hand, in the myocardium, little is known about the effects of sulfhydryl blocking reagents. KLEINFELD et al (1964) reported a decrease in the resting membrane potential and in the overshoot of action potential in hog Purkinje fibers after application of p-chloromercuribenzoic acid (PCMB), and KLEINFELD and STEIN (1968) observed a positive inotropic effect of HgCl2 on the rat atrium. Recently, HALBACH (1975) found that HgCl2 caused a rapidly developing negative inotropic effect followed by a transient increase in the contractile tension of the guinea pig papillary muscle.…”

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confidence: 99%

The Action of N-Ethylmaleimide on the Membrane Currents and Contractile Tension in the Bullfrog Atrium

Aomine

Abe

1978

Jpn.J.Physiol

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The effects of N-ethylmaleimide (NEM), a sulfhydryl blocking reagent, on the membrane currents, action potentials and contractile tension in bullfrog atrial muscle were studied by using the double sucrose gap technique. In concentrations of 10-3 to 10-4 M, NEM led to a transient enhancement of twitch contraction followed by a late inhibition, while 10-2 M NEM merely produced an inhibitory effect. The positive inotropism was accompanied by a prolongation of action potential and the negative inotropism, by a depression of action potential. Under voltage clamp conditions, 10-3 M NEM reduced the fast inward current and increased the steady state outward and background currents. The slow inward current and the inward Ca current in Na-free conditions were transiently increased by 10-3 M NEM with an enhancement of contractile tension. In voltage-tension relationships, NEM-induced augmentation of tension appeared in depolarizing pulses of 60-70 mV. The results indicate that NEM increases transiently the Ca conductance of the cell membrane. Preincubation with L-cysteine blocked the production of positive inotropic effect by NEM, suggesting that the effects of NEM are due to the blockade of protein sulfhydryl group in the atrial muscle.

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Antiarrhythmic Compounds

Szekeres

Papp

1968

Progress in Drug Research / Fortschritte Der Arzneimittelforschung / Progrès Des Recherches Pharmaceutiques

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Parachloromercuribenzoate on action potentials of Purkinje and ventricular fibers of hog heart

Cited by 6 publications

References 0 publications

Effects of Hypoxia and Metabolic Inhibitors on the Intrinsic Heart Rate and Myocardial Contractility in Dogs

Effects of Hypoxia and Metabolic Inhibitors on the Intrinsic Heart Rate and Myocardial Contractility in Dogs

The Action of N-Ethylmaleimide on the Membrane Currents and Contractile Tension in the Bullfrog Atrium

Antiarrhythmic Compounds

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