On the smooth muscle in the turtle's heart

Shaner, Ralph F.

doi:10.1002/ar.1090250203

Cited by 7 publications

(14 citation statements)

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“…The slow changes in atrial tone were clearly distinct and independent from the normal rapid contractions of the cardiac muscle (Fano, 1887). Shortly thereafter, a dense layer of smooth muscle lining the luminal side of the atrial wall was described in this species and other members of the family Emydidae (Laurens, 1913;Rosenzweig, 1903;Shaner, 1923). This smooth muscle originates in the sinus venosus and pulmonary veins and continues into the ventricle, where its distribution becomes much more sparse (Shaner, 1923).…”

Section: Introductionmentioning

confidence: 83%

“…Shortly thereafter, a dense layer of smooth muscle lining the luminal side of the atrial wall was described in this species and other members of the family Emydidae (Laurens, 1913;Rosenzweig, 1903;Shaner, 1923). This smooth muscle originates in the sinus venosus and pulmonary veins and continues into the ventricle, where its distribution becomes much more sparse (Shaner, 1923). It was also shown that the conspicuous tonus waves were sensitive to smooth-muscle-specific pharmacological substances (Snyder and Andrus, 1919), providing conclusive evidence that the unusual waves could be attributed to smooth muscle.…”

Section: Introductionmentioning

confidence: 88%

“…For instance, the smooth-muscle-dependent tonus contraction is potentiated by vagal stimulation, histamine and pituitary extract, but inhibited by sympathetic stimulation with adrenaline (Bottazzi and Grünbaum, 1899;Dimond, 1959;Fano, 1887;Fano and Fayod, 1888;Gault, 1917;Gruber, 1920aGruber, ,b, 1921Gruber, , 1927Gruber, , 1934Gruber and Markel, 1918a,b;Sollmann and Rossides, 1927). However, little consensus was reached regarding its functional role, although implications for electrical conduction or strengthening atrial contraction were suggested (Meek, 1927;Shaner, 1923). Indeed, Shaner (1923) resoundingly concluded 'it is hardly worthwhile to hazard a guess as to the function of smooth muscle in such a peculiar position'.…”

Section: Introductionmentioning

confidence: 99%

“…However, little consensus was reached regarding its functional role, although implications for electrical conduction or strengthening atrial contraction were suggested (Meek, 1927;Shaner, 1923). Indeed, Shaner (1923) resoundingly concluded 'it is hardly worthwhile to hazard a guess as to the function of smooth muscle in such a peculiar position'. Nonetheless, Gesell (1915) earlier observed that cardiac output decreased when atrial tonus spontaneously increased in perfused turtle hearts.…”

Section: Introductionmentioning

confidence: 99%

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Contraction of atrial smooth muscle reduces cardiac output in perfused turtle hearts

Joyce

Axelsson

Wang

2019

Journal of Experimental Biology

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Unusual undulations in resting tension (tonus waves) were described in isolated atria from freshwater turtles more than a century ago. These tonus waves were soon after married with the histological demonstration of a rich layer of smooth muscle on the luminal side of the atrial wall. Research thereafter waned and the functional significance of this smooth muscle has remained obscure. Here, we provide evidence that contraction of the smooth muscle in the atria may be able to change cardiac output in turtle hearts. In in situ perfused hearts of the red-eared slider turtle (Trachemys scripta elegans), we demonstrated that activation of smooth muscle contraction with histamine (100 nmol kg −1 bolus injected into perfusate) reduced cardiac output by decreasing stroke volume (>50% decrease in both parameters). Conversely, inhibition of smooth muscle contraction with wortmannin (10 µmol l −1 perfusion) approximately doubled baseline stroke volume and cardiac output. We suggest that atrial smooth muscle provides a unique mechanism to control cardiac filling that could be involved in the regulation of stroke volume during diving.

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Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Contraction of atrial smooth muscle reduces cardiac output in perfused turtle hearts

Joyce

Axelsson

Wang

2019

Journal of Experimental Biology

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“…Atrial tonus waves have been observed previously in tortoise and turtle atrial tissue (Gannon et al, 2003), and have been attributed to the presence of smooth muscle in the atria (reviewed in Meek, 1927). Histological studies have demonstrated the presence of endocardial smooth muscle in turtle atria, and more sparsely in the ventricle (Shaner, 1923;Gannon et al, 2003). When specific smooth muscle tissue poisons were applied to atrial tissue from the turtle, the 'tonus waves' were abolished (Snyder and Andrus, 1919).…”

Section: Increases In Diastolic Camentioning

confidence: 89%

The role of the sarcoplasmic reticulum in the generation of high heart rates and blood pressures in reptiles

Galli

Gesser

Taylor

et al. 2006

Journal of Experimental Biology

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Smooth Muscle in Cardiac Chambers is Common in Turtles and Extensive in the Emydid Turtle,Trachemys scripta

Joyce

Crossley

Wang

et al. 2019

The Anatomical Record

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A prominent layer of smooth muscle lining the luminal side of the atria of freshwater turtles (Emydidae) was described more than a century ago. We recently demonstrated that this smooth muscle provides a previously unrecognized mechanism to change cardiac output in the emydid red-eared slider (Trachemys scripta) that possibly contributes to their tremendous diving capacity. The purpose of the present immunohistochemical study was firstly to screen major groups of vertebrates for the presence of cardiac smooth muscle. Secondly, we investigated the phylogenetic distribution of cardiac smooth muscle within the turtle order (Testudines), including terrestrial and aquatic species. Atrial smooth muscle was not detected in a range of vertebrates, including Xenopus laevis, Alligator mississippiensis, and Caiman crocodilus, all of which have pronounced diving capacities. However, we confirmed earlier reports that traces of smooth muscle are found in human atrial tissue. Only within the turtles (eight species) was there substantial amounts of nonvascular smooth muscle in the heart. This amount was greatest in the atria, while the amount in proportion to cardiac muscle was greater in the sinus venosus than in other chambers. T. scripta had more smooth muscle in the sinus venosus and atria than the other turtles. In some specimens, there was some smooth muscle in the ventricle and the pulmonary vein. Our study demonstrates that cardiac smooth muscle likely appeared early in turtle evolution and has become extensive within the Emydidae family, possibly in association with diving. Across other tetrapod clades, cardiac smooth muscle might not associate with diving.

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On the smooth muscle in the turtle's heart

Cited by 7 publications

References 1 publication

Contraction of atrial smooth muscle reduces cardiac output in perfused turtle hearts

Contraction of atrial smooth muscle reduces cardiac output in perfused turtle hearts

The role of the sarcoplasmic reticulum in the generation of high heart rates and blood pressures in reptiles

Smooth Muscle in Cardiac Chambers is Common in Turtles and Extensive in the Emydid Turtle,Trachemys scripta

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