Epinephrine secretion correlates to calcium intensity of chromaffin granules in vitro in isolated rat adrenal medulla cells

摘要

Adrenal medulla cells release catecholamine hormone in a stimulus-secretion (S-S) coupling manner. One reason that will liberate the horomone-containing granule from the chromaffin cells is the increase of (Ca~(2+))_i within the cytosol. The raising of (Ca~(2+))_i may either caused by the inflow of calcii ion from exterior matrix through ion channels on the plasmalemma, or by the promotion of calcii ion from intracellular calcium stores of the cell. In this work, agonist of acetylcholine (ACh) and A523187 were used to induce S-S coupling phenomena in isolated rat chromaffin cells. The varied quantity of intracellular chromaffin granules as well as epinephrine released from the cells was measured. The change of the calcium content in chromaffin granules was also monitored. The relationship between the calcium content of chromaffin granules and the amount of epinephrine they released upon rat chromaffin cells will be considered to evaluate the role of chromaffin granules as a functional intracellular calcium store that mediates the S-S coupling in chromaffin cells.