Absence of catecholamine uptake mechanism in the isolated perfused adrenal gland of the rat.

The left adrenal gland of the rat was perfused in vitro via the adrenal vein with Krebs-bicarbonate solution to study accumulation of exogenous catecholamines and secretion of endogenous norepinephrine and epinephrine by exposing the gland to various sympathomimetic agents. Perfusions with high concentrations of norepinephrine for 30 min did not result in its accumulation over the endogenous norepinephrine content. High concentrations of dopamine, norepinephrine and phenylephrine failed to displace significant quantities of endogenous catecholamines in the perfusate over those secreted spontaneously. Agents known to release norepinephrine from sympathetic nerves, such as tyramine and ephedrine, were ineffective in causing secretion of catecholamines from the rat adrenal gland. We have concluded that chromaffin cells of the isolated rat adrenal gland do not exhibit an efficient uptake system across their membrane for transporting catecholamines.