title: Acute endotoxemia increases left ventricular contractility and diastolic stiffness in calves.
abstract: We investigated the acute effects of endotoxemia on left ventricular (LV) contractility, relaxation, diastolic properties, and mechanical energetics in closed-chest calves. Twelve male calves (4 to 10 days old) were anesthetized with alpha-chloralose and instrumented to measure the LV pressure-volume relationship. Calves (n = 6) in the control group remained hemodynamically stable for 4 h. Calves (n = 6) administered endotoxin (0.1 microg/kg, O55:B5, i.v., over 0.5 h) had increased heart rate, mean pulmonary artery pressure, LV contractility (end-systolic elastance), chamber stiffness, and mechanical efficiency, no change in LV relaxation, and decreased mean systemic arterial pressure, cardiac output, and LV stroke work and pressure-volume area. Endotoxin-induced changes were maximal at t = 0.5 h, after which time all hemodynamic variables gradually returned towards baseline values. Intravenous administration of isoproterenol (0.02 microg x kg(-1) x min(-1)) alone or combined with phenylephrine (5 microg x kg(-1) x min(-1)) at t = 4 h produced similar increases in heart rate, end-systolic elastance, and cardiac output in control and endotoxin-treated groups. Our findings indicate that circulatory dysfunction, rather than LV dysfunction, predominates during acute endotoxemia (4 h) in chloralose-anesthetized, closed-chest neonatal calves.
authors.affiliation: Department of Veterinary Clinical Medicine, University of Illinois, Urbana, IL 61802, USA.
authors.forename: P D
authors.initials: PD
authors.lastname: Constable
mesh_terms: D018686:Anesthetics, Intravenous / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology; D016022:Case-Control Studies; D002417:Cattle; D002698:Chloralose / Q000494:pharmacology; D003971:Diastole; D019446:Endotoxemia / Q000503:physiopathology*; D004731:Endotoxins / Q000633:toxicity; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009200:Myocardial Contraction; D010656:Phenylephrine / Q000494:pharmacology; D016277:Ventricular Function, Left
chemical_list: D018686:Anesthetics, Intravenous; D002316:Cardiotonic Agents; D004731:Endotoxins; D010656:Phenylephrine; D002698:Chloralose; D007545:Isoproterenol