Hydrostatic pressure and adrenergic drugs (agonists and antagonists): effects and interactions in fish

Cardiac responses to alpha and beta adrenergic drugs have been studied in the eel firstly at atmospheric pressure (1 ATA), secondly at 101 ATA per se hydrostatic pressure. The exposure of treated eels for 1 hr at 101 ATA cancels the propranolol effect, increases the clonidine effect and induces paradoxal effects (reversal effect) of isoproterenol, phentolamine and phenylephrine. The highly significant interaction (P less than 0.001) between drugs and HP at 101 ATA is discussed and interpreted as effects of hydrostatic pressure inducing a change in receptor function.