Influence of vascular and transpulmonary pressures on endothelial vesicles in nonedematous and edematous lungs.
We examined the effects of vascular and transpulmonary (Ptp) pressures on endothelial vesicles in nonedematous and edematous dog lungs by transmission electron microscopy (TEM). Edema was defined as a 30% increase in lung weight. Lungs were prepared for TEM by rapid freezing followed by freeze substitution. Using a random sampling procedure, the size and numerical density (Nv) of vesicles was obtained by standard morphometric techniques and the percentage of cytoplasm occupied by vesicles (Vv) calculated. Results show that at Ptp = 5 cm H2O, vascular pressure has no influence on the variables examined in nonedematous and edematous lungs. At Ptp = 25 cm H2O, increases in vascular pressure were associated with significant decreases in the percent cytoplasm occupied by vesicles for both series of experiments. When nonedematous lungs were compared to edematous lungs, we found increases in vesicle size, Nv, and the percentage of endothelial cell cytoplasm occupied by vesicles. The results confirm the increase in vesicles associated with edema. This result does not appear to be due to increased vascular pressure per se, although time related influences could be involved.
D000818:Animals; D001794:Blood Pressure; D002462:Cell Membrane / Q000502:physiology; D003593:Cytoplasm / Q000648:ultrastructure; D004285:Dogs; D004727:Endothelium / Q000502:physiology / Q000503:physiopathology* / Q000648:ultrastructure; D005615:Freezing; D008168:Lung / Q000502:physiology / Q000503:physiopathology*; D008854:Microscopy, Electron; D011312:Pressure; D011654:Pulmonary Edema / Q000503:physiopathology*