Research article summary (published 17 Aug 2009):

Comparison of sarcoplasmic reticulum calcium content in atrial and ventricular myocytes of three fish species.

Full Abstract

Ryanodine (Ry) sensitivity of cardiac contraction differs between teleost species, between atrium and ventricle, and according to the thermal history of the fish. The hypothesis that variability in Ry sensitivity of contraction is due to species-specific, chamber-specific, and temperature-related differences in the sarcoplasmic reticulum (SR) Ca(2+) content, was tested by comparing steady-state (SS) and maximal (Max) Ca(2+) loads of the SR in three teleost fish, rainbow trout (Oncorhynchus mykiss), burbot (Lota lota), and crucian carp (Carassius carassius), which differ in the extent of SR contribution to excitation-contraction coupling. Fish were acclimated at 4 degrees C (cold-acclimation, CA) or 18 degrees C (warm-acclimation, WA), and SR Ca(2+) content was released by a rapid application of 10 mM caffeine to single cardiac myocytes; its amount was determined from the Na(+)-Ca(2+) exchange current at 18 degrees C. SS Ca(2+) load was larger in atrial (304-915 micromol/l) than ventricular (224-540 micromol/l) myocytes in all fish species (P < 0.05), and the same was true for Max SR Ca(2+) content: 550-1,522 micromol/l and 438-840 micromol/l for atrial and ventricular myocytes, respectively (P < 0.05). Consistent with the hypothesis, acclimation to cold increased Ca(2+) load of the cardiac SR in the burbot heart, but contrary to the hypothesis, temperature acclimation did not affect SR Ca(2+) content in rainbow trout and crucian carp hearts. Furthermore, there was an inverse relation between SR Ca(2+) content and Ry sensitivity of contraction force: the species with the smallest SR Ca(2+) content (burbot) is most sensitive to Ry. Collectively, these findings show that SR Ca(2+) content of fish cardiac myocytes is several times larger than that in mammalian cardiac SR.

Author information

Author/s: Haverinen, Jaakko (J); Vornanen, Matti (M);

Affiliation: University of Joensuu, Faculty of Biosciences, Joensuu, Finland. jaakko.haverinen(-atsign-)joensuu.fi

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: American journal of physiology. Regulatory, integrative and comparative physiology (Am J Physiol Regul Integr Comp Physiol), published in United States. (Language: eng)

Reference: 2009-Oct; vol 297 (issue 4) : pp R1180-7

Dates: Created 2009/09/28; Completed 2009/10/13;

PMID: 19692664, status: MEDLINE (last retrieval date: 10/13/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Acclimatization Animals Caffeine - pharmacology Calcium - metabolism Calcium Channels, L-Type - metabolism Carps - metabolism Cold Temperature Fishes - metabolism Heart Atria - metabolism Heart Ventricles - metabolism

Heart Ventricles - metabolism Hot Temperature Membrane Potentials Myocardial Contraction Myocytes, Cardiac - drug effects; metabolism Oncorhynchus mykiss - metabolism Ryanodine Receptor Calcium Release Channel - metabolism Sarcoplasmic Reticulum - drug effects; metabolism Sodium-Calcium Exchanger - metabolism Species Specificity

Associated Chemicals: Calcium Channels, L-Type (0) ; Ryanodine Receptor Calcium Release Channel (0) ; Sodium-Calcium Exchanger (0) ; Caffeine (58-08-2) ; Calcium (7440-70-2)

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