Sympathetic nerve influence on alveolar type II cell ultrastructure

Pulmonary surfactant release from lamellar bodies in alveolar type II cells in response to exogenous and circulating catecholamines is well documented but sympathetic influences from direct nerve stimulation are not as extensively studied. In order to study sympathetic nerve influence on release, ultrastructure of type II cells was examined following one min stimulation of the stellate ganglion (SGS) which sends sympathetic fibers to lung parenchyma. The type II cell secretion was assessed by measuring volume density of lamellar bodies, interpreting decreased volume density to indicate increased secretion according to accepted stereologic principles. The present study showed lamellar body volume density was reduced 20.8% in type II cells of SGS animals. Multivesicular body volume density was increased 150% by SGS, but Golgi bodies were unchanged. These data are consistent with type II cell origin of at least some of the increased saturated phospholipid recovered from airspaces in previous SGS studies, and support the view that sympathetic nerve activity may contribute to surfactant homeostasis under some conditions.