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Cardiac performance in response to loading pressures in Busycon Canauculatum (Gastropoda) and Mercenaria Mercenaria (Bivalvia)

Cardiac performance in response to loading pressures in Busycon Canauculatum (Gastropoda) and Mercenaria Mercenaria (Bivalvia)
Cardiac performance in response to loading pressures in Busycon Canauculatum (Gastropoda) and Mercenaria Mercenaria (Bivalvia)
The performance of the isolated hearts of a gastropod, Busycon canaliculatum (L.), and a bivalve, Mercenaria mercenaria(L.), were examined at different perfusion levels around the expected physiological ranges. Both hearts followed the Frank-Starling relationship with regard to stroke volume versus preload, but the heart-rate response was species-dependent. The argument is developed that the molluscs might functionally apply Starling's Law of the heart to accommodate increased output during exercise.

At the expected in vivo filling pressures the power output of the two hearts was the same (15–30 × 10?6Wg?1 ventricular tissue), but the Mercenaria filling levels were considerably lower. This clearly indicates that the cardiac muscle of each of the two species has evolved to operate at specific pressure ranges.

Electrical recordings from the surface of the myocardium in the perfused Busycon hearts confirm that the shape changes reported in the literature, dealing with stretched myocardium, also occur for changes in the whole heart at realistic loading pressures. These results support previous conclusions that the cardiac output is controlled by the duration of the action potential plateau.

heart, energetics, mollusca
0022-0949
301-320
Smith, P.J.S.
003de469-9420-4f12-8f0e-8e8d76d28d6c
Smith, P.J.S.
003de469-9420-4f12-8f0e-8e8d76d28d6c

Smith, P.J.S. (1985) Cardiac performance in response to loading pressures in Busycon Canauculatum (Gastropoda) and Mercenaria Mercenaria (Bivalvia). Journal of Experimental Biology, 119 (1), 301-320.

Record type: Article

Abstract

The performance of the isolated hearts of a gastropod, Busycon canaliculatum (L.), and a bivalve, Mercenaria mercenaria(L.), were examined at different perfusion levels around the expected physiological ranges. Both hearts followed the Frank-Starling relationship with regard to stroke volume versus preload, but the heart-rate response was species-dependent. The argument is developed that the molluscs might functionally apply Starling's Law of the heart to accommodate increased output during exercise.

At the expected in vivo filling pressures the power output of the two hearts was the same (15–30 × 10?6Wg?1 ventricular tissue), but the Mercenaria filling levels were considerably lower. This clearly indicates that the cardiac muscle of each of the two species has evolved to operate at specific pressure ranges.

Electrical recordings from the surface of the myocardium in the perfused Busycon hearts confirm that the shape changes reported in the literature, dealing with stretched myocardium, also occur for changes in the whole heart at realistic loading pressures. These results support previous conclusions that the cardiac output is controlled by the duration of the action potential plateau.

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Published date: November 1985
Keywords: heart, energetics, mollusca

Identifiers

Local EPrints ID: 190591
URI: http://eprints.soton.ac.uk/id/eprint/190591
ISSN: 0022-0949
PURE UUID: e11bbd16-7b98-4645-9557-6b0c9a757181
ORCID for P.J.S. Smith: ORCID iD orcid.org/0000-0003-4400-6853

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Date deposited: 14 Jun 2011 08:58
Last modified: 15 Mar 2024 03:39

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