Comparative study of the ultrastructural alterations in the pulmonary vessels of rats treated with alpha-naphthylthiourea (ANTU) and ammonium sulphate.

A comparative study of the ultrastructural changes in rat pulmonary vessels was made in two different situtations of increased vascular permeability: one caused by alpha-naphthylthiourea (ANTU) and the other induced by ammonium sulphate (AS). AS had a more destructive effect on the capillaries but showed little alteration in vessels larger than capillaries. ANTU provoked milder ultrastructural lesions but acted on capillaries, arterial and venous structures. In both conditions intravenously injected carbon particles adhered to the vessel wall and leakage into the interstitial space was rarely seen despite the presence of endothelial gaps. It was concluded that ANTU and AS provoke different ultrastructural alterations and that pulmonary and systemic vessels react differently when undergoing changes in permeability.