In situ cardiac performance of Atlantic cod (Gadus morhua) at cold temperatures: long-term acclimation, acute thermal challenge and the role of adrenaline

• Published in: Journal of Experimental Biology
• Main Authors: Lurman, Glenn J., Petersen, Lene H., Gamperl, A. Kurt
• Format: Text
• Language: English
• Published: Company of Biologists 2012
• Subjects: Research Articles; atlantic cod; Gadus morhua; Newfoundland
• Online Access: http://jeb.biologists.org/cgi/content/short/215/22/4006; https://doi.org/10.1242/jeb.069849

The resting and maximum in situ cardiac performance of Newfoundland Atlantic cod ( Gadus morhua ) acclimated to 10, 4 and 0°C were measured at their respective acclimation temperatures, and when acutely exposed to temperature changes: i.e. hearts from 10°C fish cooled to 4°C, and hearts from 4°C fish measured at 10 and 0°C. Intrinsic heart rate ( f H ) decreased from 41 beats min−1 at 10°C to 33 beats min−1 at 4°C and 25 beats min−1 at 0°C. 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 0°C, respectively). Further, cardiac scope showed a slight positive compensation between 4 and 0°C ( Q 10 =1.7), and full, if not a slight over compensation between 10 and 4°C ( Q 10 =0.9). The maximal performance of hearts exposed to an acute decrease in temperature (i.e. from 10 to 4°C and 4 to 0°C) was comparable to that measured for hearts from 4°C- and 0°C-acclimated fish, respectively. In contrast, 4°C-acclimated hearts significantly out-performed 10°C-acclimated hearts when tested at a common temperature of 10°C (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.