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Cardiac performance in response to loading pressures and perfusion with 5-hydroxytryptamine in the isolated heart of Busycon Canaliculatum (Gastropoda, Prosobranchia)

Cardiac performance in response to loading pressures and perfusion with 5-hydroxytryptamine in the isolated heart of Busycon Canaliculatum (Gastropoda, Prosobranchia)
Cardiac performance in response to loading pressures and perfusion with 5-hydroxytryptamine in the isolated heart of Busycon Canaliculatum (Gastropoda, Prosobranchia)
In this study the effects of a molluscan neurotransmitter, 5-hydroxytryptamine (5-HT), were examined on the isolated and pumping heart of the gastropod mollusc Busycon canaliculatum. Unlike in previous studies, the response was measured in such a way as to equate it with cardiac output. In addition, the effects on the myogram form and the manner of perfusate ejection were also examined.

As would be expected from previous studies, 5-HT affects heart rate, showing a positive chronotropic response at a threshold of around 10?9 moll?1. Stroke volume shows little evidence of being regulated by 5-HT concentration. This observation was unexpected as 5-HT is commonly reported to regulate the ‘force’ of contraction in a molluscan heart and, at constant perfusion conditions, this might have been expected to find expression as an increase in stroke volume. 5-HT does, however, have a very clear dose-dependent effect on the aortic pressure pulse amplitude and duration. Amplitude increases markedly (250%) over the concentrations used (10?10-10?6moll?1) with a threshold around 10?8 moll?1 The effect on the duration has the same threshold but the opposite result, with a reduction to approximately 50% of the original value. The same amount of perfusate is therefore being ejected at a higher pressure and flow rate. It is suggested that this might have important implications for a soft-bodied animal with a hydrostatic skeleton.

The electrical activity of the heart was also examined and showed that 5-HT increased the amplitude of both the spike and plateau phase of the action potential. The duration of the latter was reduced. This is discussed with reference to other studies.

0022-0949
243-253
Smith, P.J.S.
003de469-9420-4f12-8f0e-8e8d76d28d6c
HILL, R.B.
f8855537-068c-4a5b-bbd6-87e6a4a1441a
Smith, P.J.S.
003de469-9420-4f12-8f0e-8e8d76d28d6c
HILL, R.B.
f8855537-068c-4a5b-bbd6-87e6a4a1441a

Smith, P.J.S. and HILL, R.B. (1986) Cardiac performance in response to loading pressures and perfusion with 5-hydroxytryptamine in the isolated heart of Busycon Canaliculatum (Gastropoda, Prosobranchia). Journal of Experimental Biology, 123, 243-253.

Record type: Article

Abstract

In this study the effects of a molluscan neurotransmitter, 5-hydroxytryptamine (5-HT), were examined on the isolated and pumping heart of the gastropod mollusc Busycon canaliculatum. Unlike in previous studies, the response was measured in such a way as to equate it with cardiac output. In addition, the effects on the myogram form and the manner of perfusate ejection were also examined.

As would be expected from previous studies, 5-HT affects heart rate, showing a positive chronotropic response at a threshold of around 10?9 moll?1. Stroke volume shows little evidence of being regulated by 5-HT concentration. This observation was unexpected as 5-HT is commonly reported to regulate the ‘force’ of contraction in a molluscan heart and, at constant perfusion conditions, this might have been expected to find expression as an increase in stroke volume. 5-HT does, however, have a very clear dose-dependent effect on the aortic pressure pulse amplitude and duration. Amplitude increases markedly (250%) over the concentrations used (10?10-10?6moll?1) with a threshold around 10?8 moll?1 The effect on the duration has the same threshold but the opposite result, with a reduction to approximately 50% of the original value. The same amount of perfusate is therefore being ejected at a higher pressure and flow rate. It is suggested that this might have important implications for a soft-bodied animal with a hydrostatic skeleton.

The electrical activity of the heart was also examined and showed that 5-HT increased the amplitude of both the spike and plateau phase of the action potential. The duration of the latter was reduced. This is discussed with reference to other studies.

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Published date: July 1986

Identifiers

Local EPrints ID: 190611
URI: https://eprints.soton.ac.uk/id/eprint/190611
ISSN: 0022-0949
PURE UUID: e50c50fa-2950-4497-9d91-cf3d6e511c89
ORCID for P.J.S. Smith: ORCID iD orcid.org/0000-0003-4400-6853

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Date deposited: 16 Jun 2011 14:14
Last modified: 06 Jun 2018 12:31

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Contributors

Author: P.J.S. Smith ORCID iD
Author: R.B. HILL

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