Effects of high hydrostatic pressure on catecholamine contents in tissues of the eel acclimatized at two temperatures

Catecholamines (CA) are involved in many adaptative mechanisms of an organism to its environment. In fish, pressure is an environmental factor able to modify these mechanisms of adaptation, and some of the physiological perturbations observed under pressure can be compared to CA unloading. Moreover, the metabolic rate, and probably the CA metabolism of fish, are modified by the ambient temperature. This study has been conducted to measure tissue (brain and heart) CA contents (dopamine, norepinephrine, epinephrine) of eels acclimatized for 15 d at two temperatures, Tw, (15 degrees C or 25 degrees C). The measurements have been made either at atmospheric pressure (1 ATA) or after 60 min at 101 ATA of hydrostatic pressure "per se." The results show that 1) at a given Tw, pressure has no significant effect on tissue CA contents; and 2) there seems to exist a pressure-temperature antagonism concerning dopamine and epinephrine in the brain. It is suggested that this antagonism acts on enzymatic systems involved in the metabolism of these two amines.