Endotoxin: a cause of spontaneous pulmonary hypertension in cattle?
Reeves, J.T.; Daoud, F.S.; Estridge, M.
American Journal of Veterinary Research 34(12): 1573-1576
1973
ISSN/ISBN: 0002-9645 PMID: 4762721 Document Number: 64766
Pulmonary hypertension occurred spontaneously in 35 of 304 heart catheterizations carried out on 147 young calves. The pulmonary arterial pressure began to increase to a level approximately twice normal, and remained elevated for longer than 30 minutes. There was an increase in wedge pressure, respiratory effort, and body temperature and a decrease in cardiac output and arterial oxygen tension. The spontaneous pulmonary hypertension resembled the delayed pulmonary hypertension induced in calves given endotoxin. Both spontaneous pulmonary hypertension and endotoxin-induced pulmonary hypertension were partially blocked either by giving acetylsalicylic acid (ASA) or oxygen indicating the existence of a common mechanism. The frequency of the hypertensive episodes decreased from 30% in 47 calves less than 12 hours old to 10% in 38 calves 4 to 8 weeks of age. The catheterization procedure could have introduced endotoxin or released it from endogeneous stores, thus causing spontaneous pulmonary hypertension.