Plasma catecholamines in rainbow trout (Salmo gairdneri) during hypoxia.

Plasma catecholamines (CAs) were assayed radioenzymatically in normoxic and variably hypoxic rainbow trout (Salmo gairdneri). Results were grouped according to four levels of progressively deeper hypoxemia. Only in animals where PaO2 fell below 6.7 kPa, were both adrenaline (A) and noradrenaline (NA), slightly, but significantly, increased. In contrast, substantial increases of plasma CAs occurred when PaO2 was reduced below 3.99 kPa (increment …