Platelet activating factor (PAF-acether) is released into rat pulmonary alveolar fluid as a consequence of hypoxia.
Hypoxia provokes pulmonary constriction and because PAF-acether is a very strong pulmonary constrictor, we looked for PAF-acether in lung alveolar lavage (LAL) with a biological method based on the measurement of rabbit platelet aggregation. We first demonstrated a PAF-acether secretion during bronchoalveolar lavage with sterile isotonic NaCl (pH 7.2). PAF-acether secretion was completely suppressed with isotonic NaCl containing 5 mM EDTA but lyso-PAF-acether was still present (1.9 +/- 0.55 nmoles). Upon hypobaric hypoxia, PAF-acether was detected in LAL (1.05 +/- 0.25 10(-2)nmoles). The amount of lyso-PAF-acether increased by 6 times (12.1 +/- 4.1 nmoles). These results are given for 10(4) nmoles phospholipids of LAL. They indicate that alveolar macrophages might be activated by hypobaric hypoxia, so they produce PAF-acether in the alveole. Such a process could be involved in the well-known bronchoconstriction accompanying hypoxia.
D000818:Animals; D001681:Biological Assay; D001980:Bronchi / Q000502:physiology; D004492:Edetic Acid / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D010972:Platelet Activating Factor / Q000031:analogs & derivatives / Q000502:physiology*; D010974:Platelet Aggregation; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains
C029271:O-deacetyl platelet activating factor; D010972:Platelet Activating Factor; D004492:Edetic Acid