COMPARATIVE ASPECTS OF CARDIAC CONTRACTILITY IN TELEOST FISH: CLUES ABOUT E-C COUPLING FROM ISOMETRIC STUDIES.

Isometric force measurements have had a long-standing application in the study of cardiac contractility and more recent studies of this ilk have been directed at elucidating excitation-contraction (E-C) coupling in fish hearts. This paper brings together recent discoveries, emphasizing differences among species and the effects of temperature. The importance of such an overview is tw-fold. Foremost, the isometric studies have resulted in models of E-C coupling that are currently being tested using other techniques, some of which form important contributions to this symposium. Second, emphasis on exceptional species and experimental conditions has increased and this may blur the broader picture. Therefore, we hope to clearly establish what is known, set the stage for some of the other talks, and act as a pointer for future research. Isometric force has been measured a number of species, including: hagfish (Myxine glutinosa), little skate (Raja erinacea), spiny dogfish (Squalus acanthias), black dogfish (Etmopterus spinax), white sturgeon (Acipenser transmontanus), Atlantic cod (Gadus morhua), ocean pout (Macrozoarce