Pacemaker potentials. The excitation of isolated rabbit auricles by acetylcholine at low temperatures

Marshall, J. F.; Williams, E. M. Vaughan

doi:10.1113/jphysiol.1956.sp005455

Cited by 49 publications

(8 citation statements)

References 17 publications

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“…The biphasic responses of the heart to acetylcholine have been observed by several authors (7)(8)(9)(10)(11)(12)(13)(14). The restarting effect of acetylcholine on the atrial preparation in which rhythmical contraction had been abolished by quinidine, eserine and paludrine (12,13) and by the lowering of environmental temperature (14) has been reported.…”

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confidence: 80%

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Recovering Effect of Acetylcholine on the Depressed Atrial Transmembrane Potential of the Reserpinized Rabbit by the Adrenolytics

Misu

1964

Japanese Journal of Pharmacology

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confidence: 80%

“…The restarting effect of acetylcholine on the atrial preparation in which rhythmical contraction had been abolished by quinidine, eserine and paludrine (12,13) and by the lowering of environmental temperature (14) has been reported.…”

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confidence: 99%

Recovering Effect of Acetylcholine on the Depressed Atrial Transmembrane Potential of the Reserpinized Rabbit by the Adrenolytics

Misu

1964

Japanese Journal of Pharmacology

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“…Furthermore, an addition of a small amount of acetylcholine to the bath at low temperatures caused fully propagated action potentials to appear accompanied by the development of considerable tension. 1 The present work describes the effects of low temperatures on the transmembrane potentials of pacemaker and nonpacemaker fibers in the isolated atria of rabbits. The effects of decreased temperatures on cardiac fibers have been studied previously, using the microelectrode technic (see review by Weidmann 2 ).…”

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confidence: 99%

Effects of Low Temperatures on Transmembrane Potentials of Single Fibers of the Rabbit Atrium

Marshall

1957

Circulation Research

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Lowering the temperature caused a fall in the diastolic membrane potential and action potential and an increase in the duration of the action potential in both pacemaker and nonpacemaker fibers of the rabbit atrium. Pacemaker fibers were the most resistant to cooling and continued to discharge at a temperature where all conducted action potentials and mechanical contractions had ceased. Acetylcholine (IO~7 Gm./ml.) administered at a low temperature when only pacemaker fibers were discharging, elicited propagated action potentials and contractions. This effect was associated with an increase in diastolic membrane potential towards that existing at a temperature of 30 C.

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“…Demonstration of a stimulatory effect has not as yet been achieved in the range of physiological temperatures and this factor may prove to be of the utmost importance in this regard. A possible explanation of the role of acetylcholine in mammalian cardiac automatism rests on experiments reported by Marshall and Vaughan Williams (1956). These workers found that cooling spontaneously beating rabbit atria below 20°C.…”

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confidence: 99%

Some Observations on Cardiac Automatism in Certain Animals

Jensen

1958

The Journal of General Physiology

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Certain aspects of the acetylcholine hypothesis of cardiac automatidty have been tested in dtro with spontaneously beating cardiac tissue from rabbits, rats, dams, and hagfish. The beat of atria from rabbits and rats may be depressed or excited by acetylcholine, depending upon the state of the tissue. Proguanil and cocaine inhibition of the beat in the rat may be antagonized by acetylcholine so that reversal of the depression occurs. The action of acetylcholine on the hearts of dams was found to be strictly inhibitory. Proguanil and cocaine, in contrast to their action on mammalian atria, exert a stimulatory effect on the heart of the molluscs studied. In fact, cocaine stimulated these hearts when they were inhibited by acetylcholine.Studies on the non-innervated hagtish heart revealed that this tissue is completely insensitive to the action of acetylcholine. Extracts prepared from beating hearts of this species will accelerate hypodynamic hearts of the hagiish as well as of the mussel. An extract of the neurogenic lobster heart was without effect on the hagiish heart. Proguanil was likewise ineffective in concentrations which produced inhibition and excitation in rat and clam hearts respectively.It was concluded that acetylcholine does not play a role in the myogenic automatism of all species, and that another mechanism is responsible is suggested on the basis of results obtained in the hagfish hearts.

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Pacemaker potentials. The excitation of isolated rabbit auricles by acetylcholine at low temperatures

Cited by 49 publications

References 17 publications

Recovering Effect of Acetylcholine on the Depressed Atrial Transmembrane Potential of the Reserpinized Rabbit by the Adrenolytics

Recovering Effect of Acetylcholine on the Depressed Atrial Transmembrane Potential of the Reserpinized Rabbit by the Adrenolytics

Effects of Low Temperatures on Transmembrane Potentials of Single Fibers of the Rabbit Atrium

Some Observations on Cardiac Automatism in Certain Animals

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