Performance of the heat of the hagfish,Eptatretus cirrhatus

Forster, Malcolm E.

doi:10.1007/bf01881687

Cited by 28 publications

(3 citation statements)

References 15 publications

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“…The fundamental importance of this intrinsic mechanism is evident because it is common to all vertebrate hearts examined to date. Even the primitive hagfish (Eptatretus cirrhatus (Forster in Bloch and Schneider, 1801)), which has no cardiac innervation for external cardiac control, can more than double stroke volume with increased cardiac filling pressure (Forster 1989;. The relationship between cardiac stroke volume and cardiac filling pressure is called a Starling curve.…”

Section: Intrinsic Control Of Cardiac Contractilitymentioning

confidence: 99%

Fish cardiorespiratory physiology in an era of climate changeThe present review is one of a series of occasional review articles that have been invited by the Editors and will feature the broad range of disciplines and expertise represented in our Editorial Advisory Board.

et al. 2009

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This review examines selected areas of cardiovascular physiology where there have been impressive gains of knowledge and indicates fertile areas for future research. Because arterial blood is usually fully saturated with oxygen, increasing cardiac output is the only means for transferring substantially more oxygen to tissues. Consequently, any behavioural or environmental change that alters oxygen uptake typically involves a change in cardiac output, which in fishes can amount to a threefold change. During exercise, not all fishes necessarily have the same ability as salmonids to increase cardiac output by increasing stroke volume; they rely more on increases in heart rate instead. The benefits associated with increasing cardiac output via stroke volume or heart rate are unclear. Regardless, all fishes examined so far show an exquisite cardiac sensitivity to filling pressure and the cellular basis for this heightened cardiac stretch sensitivity in fish is being unraveled. Even so, a fully integrated picture of cardiovascular functioning in fishes is hampered by a dearth of studies on venous circulatory control. Potent positive cardiac inotropy involves stimulation of sarcolemmal β-adrenoceptors, which increases the peak trans-sarcolemmal current for calcium and the intracellular calcium transient available for binding to troponin C. However, adrenergic sensitivity is temperature-dependent in part through effects on membrane currents and receptor density. The membrane currents contributing to the pacemaker action potential are also being studied but remain a prime area for further study. Why maximum heart rate is limited to a low rate in most fishes compared with similar-sized mammals, even when Q10 effects are considered, remains a mystery. Fish hearts have up to three oxygen supply routes. The degree of coronary capillarization circulation is of primary importance to the compact myocardium, unlike the spongy myocardium, where venous oxygen partial pressure appears to be the critical factor in terms of oxygen delivery. Air-breathing fishes can boost the venous oxygen content and oxygen partial pressure by taking an air breath, thereby providing a third myocardial oxygen supply route that perhaps compensates for the potentially precarious supply to the spongy myocardium during hypoxia and exercise. In addition to venous hypoxemia, acidemia and hyperkalemia can accompany exhaustive exercise and acute warming, perhaps impairing the heart were it not for a cardiac protection mechanism afforded by β-adrenergic stimulation. With warming, however, a mismatch between an animal’s demand for oxygen (a Q10 effect) and the capacity of the circulatory and ventilatory systems to delivery this oxygen develops beyond an optimum temperature. At temperature extremes in salmon, it is proposed that detrimental changes in venous blood composition, coupled with a breakdown of the cardiac protective mechanism, is a potential mechanism to explain the decline in maximum and cardiac arrhythmias that are observed. Furthermore, the fall off in scope for heart rate and cardiac output is used to explain the decrease in aerobic scope above the optimum temperature, which may then explain the field observation that adult sockeye salmon ( Oncorhynchus nerka (Walbaum in Artedi, 1792)) have difficulty migrating to their spawning area at temperatures above their optimum. Such mechanistic linkages to lifetime fitness, whether they are cardiovascular or not, should assist with predictions in this era of global climate change.

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Section: Intrinsic Control Of Cardiac Contractilitymentioning

confidence: 99%

Fish cardiorespiratory physiology in an era of climate changeThe present review is one of a series of occasional review articles that have been invited by the Editors and will feature the broad range of disciplines and expertise represented in our Editorial Advisory Board.

et al. 2009

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“…The heart operates with the lowest after load of any vertebrate animal (Davie et al 1987;Forster et al 1988;Forster, 1989). There is no coronary blood supply.…”

Section: Introductionmentioning

confidence: 99%

“…There is no coronary blood supply. Even at maximal cardiac output, the mean circulation time must exceed 5min, as the circulating blood volume is high (Forster et al 1989). Following exercise, oxygen tensions in venous blood are low (PvO2 0.47±0.2kPa, Wells et al 1986) and rise only slowly on recovery.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Two Jacuzzis and Swimming Mild Recoveries on Heart Beat Rate and Myocardial Oxygen Consumption of Swimming

Aminian

2015

CeN

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Mass Transport: Circulatory System with Emphasis on Nonendothermic Species

Crossley

Burggren

Reiber

et al. 2016

Comprehensive Physiology

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Mass transport can be generally defined as movement of material matter. The circulatory system then is a biological example given its role in the movement in transporting gases, nutrients, wastes, and chemical signals. Comparative physiology has a long history of providing new insights and advancing our understanding of circulatory mass transport across a wide array of circulatory systems. Here we focus on circulatory function of nonmodel species. Invertebrates possess diverse convection systems; that at the most complex generate pressures and perform at a level comparable to vertebrates. Many invertebrates actively modulate cardiovascular function using neuronal, neurohormonal, and skeletal muscle activity. In vertebrates, our understanding of cardiac morphology, cardiomyocyte function, and contractile protein regulation by Ca2+ highlights a high degree of conservation, but differences between species exist and are coupled to variable environments and body temperatures. Key regulators of vertebrate cardiac function and systemic blood pressure include the autonomic nervous system, hormones, and ventricular filling. Further chemical factors regulating cardiovascular function include adenosine, natriuretic peptides, arginine vasotocin, endothelin 1, bradykinin, histamine, nitric oxide, and hydrogen sulfide, to name but a few. Diverse vascular morphologies and the regulation of blood flow in the coronary and cerebral circulations are also apparent in nonmammalian species. Dynamic adjustments of cardiovascular function are associated with exercise on land, flying at high altitude, prolonged dives by marine mammals, and unique morphology, such as the giraffe. Future studies should address limits of gas exchange and convective transport, the evolution of high arterial pressure across diverse taxa, and the importance of the cardiovascular system adaptations to extreme environments. © 2017 American Physiological Society. Compr Physiol 7:17-66, 2017.

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Performance of the heat of the hagfish,Eptatretus cirrhatus

Cited by 28 publications

References 15 publications

Fish cardiorespiratory physiology in an era of climate changeThe present review is one of a series of occasional review articles that have been invited by the Editors and will feature the broad range of disciplines and expertise represented in our Editorial Advisory Board.

Fish cardiorespiratory physiology in an era of climate changeThe present review is one of a series of occasional review articles that have been invited by the Editors and will feature the broad range of disciplines and expertise represented in our Editorial Advisory Board.

Comparison of Two Jacuzzis and Swimming Mild Recoveries on Heart Beat Rate and Myocardial Oxygen Consumption of Swimming

Mass Transport: Circulatory System with Emphasis on Nonendothermic Species

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