Plasma catecholamines in the lesser spotted dogfish and rainbow trout at rest and during different levels of exercise

The hypothesis that there is an increase in plasma catecholamines during exercise in fish and that they play an important role in the cardiovascular adjustments during exercise was investigated in the lesser spotted dogfish and rainbow trout. In resting fish plasma catecholamines were at a concentration of 10~9—10~8moll~1. During spontaneous swimming in the dogfish, adrenaline increased by 3-3 times to l-9xlO~8moll~1 and noradrenaline increased by 2-3 times to 3-2X 10~8moll~1. In rainbow trout swimming at a steady 1 body lengths"1 (Ls"1) in a water channel, the levels of both amines decreased to approximately 25 % of the resting values. When swimming to apparent exhaustion at approximately 2 L s ~ \ adrenaline was 10 times the resting value at 1-4X 10~8moll~1, whereas noradrenaline was 2-2 times the resting value at 2-3xlO~8moll~1. Only after repeated burst swimming for 2-3 min did the levels of plasma catecholamines increase substantially above the resting values. In the dogfish, both amines were at lCT'molP1, whereas in the rainbow trout, noradrenaline was at 8-5xlO~8moll~ ' and adrenaline was at 2xlO~7moll~1. These levels were compared with the concentrations of catecholamines used b