The Sarcoplasmic Reticulum in the Vertebrate Heart

Galli, Gina L. J.; Shiels, Holly A.

doi:10.1007/978-1-4614-3387-3_5

Cited by 8 publications

(10 citation statements)

References 82 publications

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“…Indeed, in mammalian preparations it has previously 287 been shown that cyanide increases calcium release from the SR and/or mitochondria (Jundt, 288 et al, 1975), and further, calcium release from the SR is essential for the recovery of force 289 production during acidosis (Orchard, 1987). This supports our hypothesis that the SR is vital 290 during anoxia in the cockle, and also lends support to the developing view that the SR is a 291 key regulator of calcium homeostasis during environmental stress (Galli and Shiels, 2012). 292…”

supporting

confidence: 80%

Myocardial force generation and anoxia tolerance in the common cockle, Cerastoderma edule

Joyce

Ozolina

Shiels

2014

Preprint

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The myocardium of molluscs exhibits profound anoxia tolerance, however the cellular mechanisms underlying heart performance during normoxia and anoxia are not well understood. In the present study we investigated the role of the sarcoplasmic reticulum (SR) during normoxia and chemical anoxia (2 mM sodium cyanide) in electrically paced ventricle preparations from the common cockle (Cerastoderma edule) at ~19°C. Acute anoxia caused a substantial increase in resting tension but did not significantly affect the force of contraction, rate of contraction or rate of relaxation in myocardial preparations. SR inhibition (ryanodine, 10 µM; thapsigargin, 2 µM) attenuated the increase in resting tension, and also caused a significant decrease in the force of contraction during anoxia. During normoxia, SR inhibition reduced the force and rate of contraction by 20-30 % at contraction frequencies of 0.2 Hz and 0.5 Hz. SR inhibition also elicited an increase in resting tension at 0.5 Hz. Our results suggest that the SR plays a role in maintaining cardiac performance during anoxia in cockle myocardium. Furthermore, the SR is operative during normoxia and is relatively more important in the cockle heart than in many ectothermic vertebrates. As efforts to understand the evolution of the SR are advanced, anoxia tolerant invertebrates may serve as valuable model organisms.

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supporting

confidence: 80%

Myocardial force generation and anoxia tolerance in the common cockle, Cerastoderma edule

Joyce

Ozolina

Shiels

2014

Preprint

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“…Kashyap, ). In fish, the morphology of cardiomyocytes of the spongy and compact myocardium is alike (Di Maio & Block, ), but similar comparisons have not been made in reptiles and possible functional differences remain to be studied (Galli & Shiels, ). The compact layers are supplied with blood from coronary arteries (see Section II.6), whereas the spongy part, as in all other ectothermic vertebrates, is bathed in the blood returning to the heart (Benninghoff, ; Ošťádal, Rychter & Poupa, ; Kashyap, ; Poupa, ; Pieperhoff, Bennett & Farrell, ; Jensen et al , 2010 a, c ).…”

Section: Reptile Heartsmentioning

confidence: 99%

Structure and function of the hearts of lizards and snakes

2013

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With approximately 7000 species, snakes and lizards, collectively known as squamates, are by far the most species-rich group of reptiles. It was from reptile-like ancestors that mammals and birds evolved and squamates can be viewed as phylogenetically positioned between them and fishes. Hence, their hearts have been studied for more than a century yielding insights into the group itself and into the independent evolution of the fully divided four-chambered hearts of mammals and birds. Structurally the heart is complex and debates persist on rudimentary issues such as identifying structures critical to understanding ventricle function. In seeking to resolve these controversies we have generated three-dimensional (3D) models in portable digital format (pdf) of the anaconda and anole lizard hearts ('typical' squamate hearts) and the uniquely specialized python heart with comprehensive annotations of structures and cavities. We review the anatomy and physiology of squamate hearts in general and emphasize the unique features of pythonid and varanid lizard hearts that endow them with mammal-like blood pressures. Excluding pythons and varanid lizards it is concluded that the squamate heart has a highly consistent design including a disproportionately large right side (systemic venous) probably due to prevailing pulmonary bypass (intraventricular shunting). Unfortunately, investigations on rudimentary features are sparse. We therefore point out gaps in our knowledge, such as the size and functional importance of the coronary vasculature and of the first cardiac chamber, the sinus venosus, and highlight areas with implications for vertebrate cardiac evolution.

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“…The functional role of the SR is heterogeneous in ectotherms and has been reviewed recently (47). In the majority of ectothermic species, atrial and ventricular myocyte contractions do not require Ca 2ϩ release from the SR. Contraction is supported exclusively by transsarcolemmal Ca 2ϩ flux through LTCCs (144,151,152), and in some cases with contribution from reverse-mode NCX (62,153).…”

Section: Functional Role Of the Srmentioning

confidence: 99%

“…dependent on SR Ca 2ϩ cycling, have greater steady-state and maximal SR Ca 2ϩ contents than their mammalian counterparts (47,48,60) (see FIGURE 4). If all vertebrates can store significant quantities of Ca 2ϩ in the SR, why is it released in some species and not others?…”

mentioning

confidence: 99%

The Sarcoplasmic Reticulum and the Evolution of the Vertebrate Heart

Shiels

Galli

2014

Physiology

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The sarcoplasmic reticulum (SR) is crucial for contraction and relaxation of the mammalian cardiomyocyte, but its role in other vertebrate classes is equivocal. Recent evidence suggests differences in SR function across species may have an underlying structural basis. Here, we discuss how SR recruitment relates to the structural organization of the cardiomyocyte to provide new insight into the evolution of cardiac design and function in vertebrates.

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The Sarcoplasmic Reticulum in the Vertebrate Heart

Cited by 8 publications

References 82 publications

Myocardial force generation and anoxia tolerance in the common cockle, Cerastoderma edule

Myocardial force generation and anoxia tolerance in the common cockle, Cerastoderma edule

Structure and function of the hearts of lizards and snakes

The Sarcoplasmic Reticulum and the Evolution of the Vertebrate Heart

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