title: Platelet-activating factor effects on pulmonary ultrastructure in rabbits.
abstract: Morphometric analysis of endothelium in rabbit lungs demonstrated a dramatic effect of platelet-activating factor (PAF) on the ultrastructure of pulmonary vasculature. Plasmalemmal vesicles in capillaries were increased both in size (638 A PAF vs 538 A control) and in number (386/micrograms 3 cytoplasm PAF vs 125/micrograms 3 cytoplasm control) when PAF was administered as a single acute low dose (chi less than 3 micrograms/kg). High concentrations of PAF (chi greater than 3 micrograms/kg) as a single acute dose also increased vesicle number (203/micrograms 3 cytoplasm), but frequently precipitated the respiratory distress syndrome. Chronic administration of PAF with daily doses over periods of either 3.5 or 7 weeks resulted in changes paralleling the acute observations, but did not lead to more extensive lung disease.
mesh_terms: D000818:Animals; D002196:Capillaries / Q000648:ultrastructure*; D002462:Cell Membrane / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D004727:Endothelium / Q000648:ultrastructure; D008168:Lung / Q000098:blood supply* / Q000187:drug effects; D008854:Microscopy, Electron; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011817:Rabbits; D012128:Respiratory Distress Syndrome / Q000139:chemically induced
chemical_list: D010972:Platelet Activating Factor