Electron translucent vesicles in adrenal medulla following catecholamine depletion

Abstract

The fine structure of rabbit adrenal chromaffin cells was examined prior to, and at various times after, hypoglycemic stress-induced release of catecholamines. At the time of maximum catecholamine depletion, 12 hr after insulin-induced hypoglycemic stress, the ratio of electron translucent vesicles to total vesicles was greatest. Return of this ratio to control values occurred when catecholamine levels returned to prestimulation values. Likewise, the ratio of dense core vesicles to total vesicles decreased as the catecholamine level decreased and returned to control values concomitantly with the return of the catecholamines to their prestimulation levels. A rise in the ratio of dense core microvesicles to translucent microvesicles when the catecholamine levels are returning to their prestimulation values suggests that the dense core microvesicles may represent vesicles in the process of synthesizing or accumulating catecholamines. It is concluded that the translucent vesicles arise from dense core chromaffin vesicles and decrease in number as the catecholamine stores are replenished.