Rhythmicity and Automatism in the Mammalian Left Auricle

Rothberger, C. J.; Sachs, Adam

doi:10.1113/expphysiol.1939.sp000795

Cited by 21 publications

(8 citation statements)

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“…Histamine is present in the tissues of the body in quantities which are toxic when liberated.37 When added to fluid bathing nonrhythmic heart tissues, histamine has induced rhythmic activity.38 39 Cardiac muscle releases histamine-like substance continuously. The amount is increased by increasing the work of the heart, by anoxia and by increased carbon dioxide."'…”

Section: Resultsmentioning

confidence: 99%

Delayed Development of Ventricular Ectopic Rhythms following Experimental Coronary Occlusion

1950

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Following aseptic occlusion of the anterior descending artery of the dog's heart ectopic ventricular tachycardia develops after a latency of four and one-half to eight hours, and persists for two to four days. Large gross infarcts are found in all hearts. The duration of latency of onset of major ectopic activity approximates the minimal period of ischemia required to produce histologic signs of necrosis. It is suspected that products or processes of necrosis have excitatory effects on tissues bounding the ischemic zone. Evidences concerning various possible excitatory factors are briefly reviewed.

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Section: Resultsmentioning

confidence: 99%

Delayed Development of Ventricular Ectopic Rhythms following Experimental Coronary Occlusion

1950

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“…This led Paes to postulate th at the norm al cardiac rhythm was due to the tonic action of the heart nerves by the constant liberation of acetylcholine (vagus) and adrenalin (sympathetic), together with a chemical substance 124 F. DAVIES AND E. T. B. FRANCIS ON specific to the nodal tissue. Rothberger and Sachs (1939) criticized the work of Demoor, and found that strips of the left atrium of the rabbit and guinea-pig which contain no nodal tissue (the specimens were examined histologically by Aschoff) exhibited spontaneous rhythm ical contractions when immersed in nutrient fluid; the rhythm of these strips was slower than th at of the S-A node. The absence of nodal tissue in the salam ander heart, which exhibits the same phenom enon of intrinsic rhythmicity as the m am m alian heart, appears to indicate th at nodal tissue is not essential as a source of a substance responsible for rhythm icity alone.…”

Section: T H E H Ea R T O F T H E Salam Ander T23mentioning

confidence: 99%

The heart of the salamander ( salamandra salamandra l. ), with special reference to the conducting (connecting) system and its bearing on the phylogeny of the conducting systems of mammalian and avian hearts

Davies

Francis

1941

Phil. Trans. R. Soc. Lond. B

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Nine salamander hearts have been studied histologically by means of serial sections, cut in each of three planes (transverse, frontal and sagittal), and stained with haemalum and eosin, van Gieson's acid fuchsin and iron-haematoxylin, and by the protargol method of Bodian. I his study has demonstrated muscular continuity between the several cardiac chambers, and the entile absence of any specialized muscle or ‘nodal tissue’ at the junctional sites or in any other part of the heart. The heart muscle forms a continuum. The cardiac muscle fibres are characterized by their large size (i.e. breadth); they have the same general histological characters in all parts of the heart. Measurements are given for the fibres from various parts of the hearts of the salamander and frog. The muscular connexions between the various cardiac chambers have been studied in detail. In each of the chambers the musculature is arranged in a basket-work fashion, but at each of the junctional sites the muscle suddenly changes to a regular circular arrangement. The sinus, at its junction with the right atrium, contains muscle only in its ventral wall, and it is this wall only of the sinus which thus establishes muscular continuity with the ring of muscle (S-A ring) around the sinu-atrial opening. The musculature of both atria is continuous with that of the ventricle in two ways. From the ring of muscle (A-V ring) surrounding the common opening of the atria into the ventricle, the atrio-ventricular funnel dips down into the ventricle, and the caudal border of this funnel is continuous ( a ) with an invaginated part of the base of the ventricle, and ( b ) more extensively with ventricular papillary muscles, which, in their turn, are continued into the inner ventricular trabeculae about the middle level of the ventricle. The A-V funnel is homogeneous in structure; no one part of its circumference differs from another. The ventricular muscle is directly continued into that of the bulbus cordis, in which latter chamber the muscle is entirely circular. The course which the wave of contraction takes during its transmission from the sinus throughout the heart has been deduced from the study of the details of the continuity of the musculature of the various cardiac chambers. To a large extent this deduction has been confirmed by superimposing tracings of the outline of the pulsating heart, made from the slow-motion cinephotographic records. This latter study has revealed many of the details of the phases of the cardiac cycle. The delay in the transmission of the wave of contraction from one cardiac chamber to the next is accounted for by the relatively long path which the impulse has to traverse at the junctional sites, where the muscle is arranged in a circular fashion, without postulating the existence of specialized ‘block fibres’ at these sites. The branching of the muscle fibres has the effect of converting the morphological circular arrangement of the fibres at these junctions into a physiological spiral. The glycogen content of the various parts of the frog’s heart, as revealed by staining with carmine, is found to increase in the order sinus, atria, ventricle and bulbus cordis. This is correlated with a similar increasing order of density of musculature and work done, the glycogen being a reserve potency for the energy of muscular contraction. The fact that the intrinsic rhythmic rates of the several chambers decrease in the same order as the glycogen content increases may or may not be coincidental. Cutting and ligature experiments, with cinephotographic and kymographic records, reveal the intrinsic rhythmic rates of the various cardiac chambers of the salamander heart. No satisfactory reason has yet been adduced to account for the different intrinsic rhythmic rates of the several parts of the heart when these are isolated from each other. The dorsal mesocardium has been traced in its entirety. The sinu-ventricular fold is a part of the continuous dorsal mesocardium and does not constitute a direct muscular sinuventricular connexion. The distribution of the intracardiac nerve cells has been noted and the probable pathway of migration of these nerve cells in the embryo has been suggested. The significance of the results of this investigation in relation to the phylogeny of the specialized conducting system of the hearts of homoiothermal vertebrates (mammals and birds) is discussed. The view is expressed that the cardiac conducting systems of homoiothermal vertebrates constitute a neomorphic development, correlated with functional requirements, and are not remnants of more extensive tissues of similar structure in the lower vertebrate heart. Variations in this newly evolved formation probably account for the different descriptions of such elements in various mammalian and avian hearts.

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“…Even in muscle strips of the left atrium from guinea pigs and rab bits, spontaneous beating was seen in 7 out of 65 experiments. In some cases the rhythmic contractions appeared only after adre naline had been added to the nutrient solution (19). The authors concluded that the left atrium possesses a feeble and irregular automatism.…”

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confidence: 96%