Adenylate cyclase in paraneurons. A histochemical study.

Adenylate cyclase activity in the taste buds of the papilla vallata of the tongue, in the EC cells of the duodenal mucosa and in the chromaffin cells of the adrenal medulla of the hamster was histochemically examined using the method invented by Wagner and co-workers (1972). Two types of taste bud cells were distinguished. The dark cell was characterized by a dark cytoplasm: the light cell, by a clear-looking cytoplasm. When AMP-PNP was used as a substrate, and intense activity was demonstrated along the microvilli of all cells in the taste bud. Much weaker activity was demonstrated on the lateral cell membrane. After the use of ATP, the reaction products were found rather evenly distributed over the surface of the taste bud cell. The synaptic area on the surface of the light cell, however, was devoid of reaction products. Among the several kinds of basal-granulated gut cells examined, the EC cell of the duodenal mucosa was one. An intense activity was demonstrated along the microvilli after the use of AMP-PNP. When ATP was used as a substrate, a positive reaction was demonstrated on the lateral cell membranes as well as on the luminal microvilli; the reaction on the microvilli was much stronger than that on the lateral cell membrane. The chromaffin cells of the adrenal medulla showed almost no activity with AMP-PNP. However, when ATP was used, the plasma membrane of Schwann cells and axons showed an intense reaction. The cell membrane of the adrenaline and noradrenaline-storing cells showed a slightly positive reaction. The synaptic area of chromaffin cell was always negative in the reaction. The positive adenylate cyclase activity in the gustatory cells and gut endocrine cells may have some relation to the stimulus reception. This is in keeping with the observation that adrenal medulla chromaffin cells, which were embedded in the internal milieu, did not react to adenylate cyclase.