Document Detail

Changes in cardiac performance during hypoxic exposure in the grass shrimp Palaemonetes pugio.
MedLine Citation:
PMID:  22071181     Owner:  NLM     Status:  MEDLINE    
In hearts of higher invertebrates as well as vertebrates, the work performed by the ventricle is a function of both rate and contractility. Decapod crustaceans experience a hypoxia-induced bradycardia that is thought to result in an overall reduction in cardiac work; however, this hypothesis has not yet been tested and is the primary purpose of this study. In the grass shrimp Palaemonetes pugio, cardiac pressure and area data were obtained simultaneously, and in vivo, under normoxic (20.2 kPa O(2)) and hypoxic (6.8 or 2.2 kPa O(2)) conditions and integrated to generate pressure-area (P-A) loops. The area enclosed by the P-A loop provides a measure of stroke work and, when multiplied by the heart rate, provides an estimate of both cardiac work and myocardial O(2) consumption. Changes in intra-cardiac pressure (dp/dt) are correlated to the isovolemic contraction phase and provide an indication of stroke work. At both levels of hypoxic exposure, intra-cardiac pressure, dp/dt, stroke work and cardiac work fell significantly. The significant decrease in intra-cardiac pressure provides the primary mechanism for the decrease in stroke work, and, when coupled with the hypoxia-induced bradycardia, it contributes to an overall fall in cardiac work. Compared with normoxic P-A loops, hypoxic P-A loops (at both levels of hypoxia) become curvilinear, indicating a fall in peripheral resistance (which might account for the reduction in intra-cardiac pressure), which would reduce both stroke work and cardiac work and ultimately would serve to reduce myocardial O(2) consumption. This is the most direct evidence to date indicating that the hypoxia-induced bradycardia observed in many decapod crustaceans reduces cardiac work and is therefore energetically favorable during acute exposure to conditions of low oxygen.
Jutta A Guadagnoli; Kimimasa Tobita; Carl L Reiber
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  214     ISSN:  1477-9145     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-11-10     Completed Date:  2012-02-29     Revised Date:  2014-08-18    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  3906-14     Citation Subset:  IM    
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MeSH Terms
Blood Circulation / physiology
Heart / physiopathology*
Palaemonidae / physiology*
Systole / physiology
Ventricular Function / physiology
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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