Swelling-induced catecholamine secretion recorded from single chromaffin cells

We have studied osmotically induced catecholamine secretion from bovine adrenal chromaffin cells by combining patch-damp measurements, electrochemical detection of secretion, and Fura-2. measurements of intracellular free calcium concentration ([Ca2+](i)). We find that osmotically induced catecholamine release is exocytotic and calcium dependent. Furthermore, we demonstrate that cell swelling is coupled to such secretion via a volume-activated current, carrying predominantly chloride, which causes a plateau depolarization of the cell membrane potential and thus promotes voltage-activated calcium influx. Therefore, cell volume changes may modulate the secretory activity.