Mechanisms of Surfactant Exocytosis in Alveolar Type II Cells In Vitro and In Vivo

Paul Dietl , Thomas Haller , Norbert Mair and Manfred Frick Department of Physiology, University of Innsbruck, A-6020 Innsbruck, Austria Surfactant secretion must be regulated to maintain a low surface tension in the lung during various conditions such as exercise. In vitro studies reveal a slow, unique exocytotic process at the interface of stimulated and constitutive exocytosis. The exocytotic mechanisms and sites of regulation in vivo, however, are still poorly understood.