Comparative effect of insulin and explanted adrenal medullary tissue and rat adrenal medulla in situ.

The adrenal medulla and explanted medullary cells in the anterior chamber of the eye were examined 3 h after the administration of insulin to rats. No alterations were seen in the explanted cells. In the adrenal medulla, light and electron microscopy indicated depletion of adrenaline cells; noradrenaline cells were not affected. Levels of catecholamines were three times higher in the explanted tissue after insulin treatment; in the medulla in situ they declined by 70%. These results confirm that insulin has no direct releasing effect on chromaffin cells.