In situ cardiac performance of Atlantic cod (Gadus morhua) at cold temperatures: long-term acclimation, acute thermal challenge and the role of adrenaline.
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
The resting and maximum in situ cardiac performance of Newfoundland Atlantic cod (Gadus morhua) acclimated to 10, 4 and 0C were measured at their respective acclimation temperatures, and when acutely exposed to temperature changes: i.e. hearts from 10C fish cooled to 4C, and hearts from 4C fish measured at 10 and 0C. Intrinsic heart rate (f(H)) decreased from 41 beats min(-1) at 10C to 33 beats min(-1) at 4C and 25 beats min(-1) at 0C. However, this degree of thermal dependency was not reflected in maximal cardiac output (Q(max) values were ~44, ~37 and ~34 ml min(-1) kg(-1) at 10, 4 and 0C, respectively). Further, cardiac scope showed a slight positive compensation between 4 and 0C (Q(10)=1.7), and full, if not a slight over compensation between 10 and 4C (Q(10)=0.9). The maximal performance of hearts exposed to an acute decrease in temperature (i.e. from 10 to 4C and 4 to 0C) was comparable to that measured for hearts from 4C- and 0C-acclimated fish, respectively. In contrast, 4C-acclimated hearts significantly out-performed 10C-acclimated hearts when tested at a common temperature of 10C (in terms of both Q(max) and power output). Only minimal differences in cardiac function were seen between hearts stimulated with basal (5 nmol l(-1)) versus maximal (200 nmol l(-1)) levels of adrenaline, the effects of which were not temperature dependent. These results: (1) show that maximum performance of the isolated cod heart is not compromised by exposure to cold temperatures; and (2) support data from other studies, which show that, in contrast to salmonids, cod cardiac performance/myocardial contractility is not dependent upon humoral adrenergic stimulation.
