Hemodynamics, plasma eicosanoid concentrations, and plasma biochemical changes in calves given multiple injections of Escherichia coli endotoxin
Templeton, C.B.; Bottoms, G.D.; Fessler, J.F.; Turek, J.J.
American Journal of Veterinary Research 49(1): 90-95
1988
ISSN/ISBN: 0002-9645 PMID: 3281526 Document Number: 313975
Twelve male neonatal calves (39 to 50 kg) were allotted to 3 groups of 4 calves each. All calves were anesthetized with halothane, and then Escherichia coli endotoxin was given intravenously (3 times) and intraperitoneally (3 times) during a 6-hour period. Group-1 calves were untreated, group-2 calves were pretreated with a low dose of flunixin meglumine (1.1 mg/kg of body weight), and group-3 calves were pretreated with a high dose of flunixin meglumine (4.4 mg/kg). In calves of group 1, the mean systemic arterial blood pressure (MABP) and cardiac output (CO) decreased, but pulmonary arterial pressure increased after the initial intravenous and intraperitoneal injections of endotoxin. In calves of this group, these changes were accompanied by increased plasma thromboxane B2 (TxB2) concentration. During this period, increased plasma TxB2 concentration or hemodynamic changes were not detected in calves of groups 2 and 3. Only calves of group 1 had altered hemodynamics early in the experiment; however, after 6 hours, calves of all 3 groups had similarly decreased CO and MABP. In calves of the untreated group, plasma 6-keto-prostaglandin (PG)F1.alpha. concentration increased steadily from the beginning of the experiment until 3 hours later. The CO and MABP were low at the time when serum 6-keto-PGF1.alpha. concentration was high; however, these 2 measurements also were low in treated calves who did not have correspondingly high plasma 6-keto-PGF1.alpha. concentration. Regional blood flow analysis did not reveal correlations between prostanoid concentrations and altered blood flow to selected tissues. Results indicated that endotoxin given to calves caused increases in plasma TxB2 and 6-keto-PGF1.alpha. concentrations, along with hemodynamic changes similar to those observed in other species. Flunixin meglumine (1.1 mg/kg) administration prevented the increase in plasma eicosanoid concentrations and the associated hemodynamic changes during early shock. However, in treated calves, after 3 hours, the CO and MABP also were decreased without a corresponding increase of plasma 6-keto-PGF1.alpha. concentration. Therefore, something other than increased prostacyclin accumulation may have caused the later decrease in CO and MABP.