Oscillatory Ca2+ signals evoked by cholinergic stimulation in isolated ratpancreatic duct cells

Acetylcholine has been known to potentiate secretin-stimulated bicarbonate secretion by the pancreatic duct system. Recent studies have shown that thi s phenomenon is at least partially attributable to the agonist-induced elev ation of intracellular Ca2+ concentration ([Ca2+](i)) in pancreatic duct ce lls. In order to define spatiotemporal dynamics of these [Ca2+](i) signals, short segments of intralobular and interlobular ducts were isolated from t he rat pancreas and examined by digital image microscopy using a calcium-se nsitive, fluorescent probe, Fura-2. In accord with previous reports by micr ospectrofluorometry, duct segments stimulated with carbachol consistently d isplayed [Ca2+](i) rises, which were specifically suppressed by atropine. P resent image analyses additionally demonstrated a fine fluctuate unevenness of the [Ca2+](i) level in the duct epithelium during the stimulation, sugg esting an asynchronous oscillatory mode of response of the pancreatic duct cells.