The Ultrastructure of the Sinu-Atrial Node of the Bat

Laskowski, Michael B.; D'Agrosa, Louis S.

doi:10.1159/000145774

Cited by 7 publications

(2 citation statements)

References 19 publications

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“…In mammals, basal heart rates are inversely correlated with the body weight. Smaller mammals such as mice and bats have fast heart rate, ranging from ϳ500 beats/min in mice during daytime (157) to 800 -1,000 beats/min in flying bats (269). In contrast, the heart rate in medium-sized and larger mammals can vary between 60 and 70 beats/min in humans and ϳ20 beats/min in whales (see Ref.…”

Section: A Principlesmentioning

confidence: 99%

Genesis and Regulation of the Heart Automaticity

Mangoni

Nargeot²

2008

Physiological Reviews

508

565

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The heart automaticity is a fundamental physiological function in higher organisms. The spontaneous activity is initiated by specialized populations of cardiac cells generating periodical electrical oscillations. The exact cascade of steps initiating the pacemaker cycle in automatic cells has not yet been entirely elucidated. Nevertheless, ion channels and intracellular Ca(2+) signaling are necessary for the proper setting of the pacemaker mechanism. Here, we review the current knowledge on the cellular mechanisms underlying the generation and regulation of cardiac automaticity. We discuss evidence on the functional role of different families of ion channels in cardiac pacemaking and review recent results obtained on genetically engineered mouse strains displaying dysfunction in heart automaticity. Beside ion channels, intracellular Ca(2+) release has been indicated as an important mechanism for promoting automaticity at rest as well as for acceleration of the heart rate under sympathetic nerve input. The potential links between the activity of ion channels and Ca(2+) release will be discussed with the aim to propose an integrated framework of the mechanism of automaticity.

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Section: A Principlesmentioning

confidence: 99%

Genesis and Regulation of the Heart Automaticity

Mangoni

Nargeot²

2008

Physiological Reviews

508

565

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“…First of all, the anatomic architecture of the SN has often been described as devoid of a definitive shape or an organized structure [ 4 – 10 ]. The results of the 3D reconstructions of the atrial elements [ 11 – 14 ] and the mathematical [ 15 , 16 ] and ultrastructural models [ 17 ] of the SN are strongly divergent. The fact that the SN presents a different shape in humans, as compared to other mammals, complicates the task of creating a reliable model of this structure even more [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

SEM, TEM, and IHC Analysis of the Sinus Node and Its Implications for the Cardiac Conduction System

Mandrioli

Ceci

Balbi

et al. 2013

Anatomy Research International

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More than 100 years after the discovery of the sinus node (SN) by Keith and Flack, the function and structure of the SN have not been completely established yet. The anatomic architecture of the SN has often been described as devoid of an organized structure; the origin of the sinus impulse is still a matter of debate, and a definite description of the long postulated internodal specialized tract conducting the impulse from the SN to the atrioventricular node (AVN) is still missing. In our previously published study, we proposed a morphologically ordered structure for the SN. As a confirmation of what was presented then, we have added the results of additional observations regarding the structural particularities of the SN. We investigated the morphology of the sinus node in the human hearts of healthy individuals using histochemical, immunohistochemical, optical, and electron microscopy (SEM, TEM). Our results confirmed that the SN presents a previously unseen highly organized architecture.

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Lymph heart musculature in birds

Budras

Hullinger

Rautenfeld

1987

Journal of Morphology

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Development and innervation of the lymph heart musculature of chicken, emu, rhea, and duck was studied by electron microscopy at post-hatch ages from 3 days to adulthood. Development of innervation was monitored by acetylcholinesterase staining. Horseradish peroxidase was used to determine the extent of the transverse tubule network. Chickens were unusual among these birds in that lymph heart myocytes had already undergone a definitive differentiation and degeneration by 3 days. In ducks and ratite birds, lymph heart myocytes more slowly but progressively differentiate a cytomorphology that does not conform in all characteristics to cardiac or skeletal muscle and even resembles in some aspects, smooth muscle. Myofibrils become the dominant cytoplasmic structure, transverse tubules form "internal couplings" with agranular reticulum cisternae, and "external couplings" are formed between myocytes at myomyal junctions. The myomyal junctions also contain AChE-positive reaction product and some subplasmalemmal vesicles that lack a dense core. The lymph heart myocardium of ducks of 2 weeks demonstrated mitotic figures. In adult ducks the myosatellite cell numbers diminish and a characteristic pattern of myocyte degeneration appears. In juvenile ducks and ratites some myocytes differentiate to conductile cells, much as the conductile myocytes and myofibers of the blood heart. The lymph heart innervation is described, and the role of nerve in differentiation and maintenance of myocyte morphology in the lymph heart is discussed.

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The Ultrastructure of the Sinu-Atrial Node of the Bat

Cited by 7 publications

References 19 publications

Genesis and Regulation of the Heart Automaticity

Genesis and Regulation of the Heart Automaticity

SEM, TEM, and IHC Analysis of the Sinus Node and Its Implications for the Cardiac Conduction System

Lymph heart musculature in birds

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