title: Diaphragmatic failure during group B streptococcal sepsis in piglets: the role of thromboxane A2.
abstract: Group B Streptococcus (GBS) causes an impairment of diaphragmatic pressure generation (Pdi) in 2-wk-old piglets, whereas 4-wk-old piglets are unaffected. In this study, we examined the effect on 4-wk-old piglets of a higher dose of GBS than previously utilized. We sought to determine whether an eicosanoid product of arachidonic acid metabolism accounted for the decrease in Pdi during GBS infusion and whether thromboxane A2 (TxA2) is the putative eicosanoid mediator of decreased Pdi during GBS infusion. Measuring Pdi during phrenic nerve stimulation, we studied four groups of anesthetized spontaneously breathing 4-wk-old piglets. Group 1 (GBS) was infused with live GBS, which caused a decrease in Pdi by 1 h at 20-, 30-, 50-, and 100-Hz stimulation frequencies. Group 2 [GBS + indomethacin (Indo)] was pretreated with Indo before GBS infusion. In the GBS + Indo group, Pdi did not decrease throughout 4 h of GBS infusion. Because Indo proved to be protective of Pdi during GBS infusion, we examined the role of TxA2, the only eicosanoid present at 1 h in the serum of GBS-infused piglets. Group 3 was infused with the TxA2 analogue U-46619 only for 1 h. Group 4 was treated with the TxA2-receptor antagonist SQ-29548 before and concomitant with GBS infusion for 1 h; the SQ-29548 was then discontinued, and GBS was continued for 1 h more. In the U-46619-infused group, Pdi decreased at 1 h, and in the SQ-29548-treated group, Pdi did not decrease during GBS infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pediatrics, University of Washington, Seattle 98195, USA.
authors.forename: T D
authors.initials: TD
authors.lastname: Murphy
authors.forename: R L
authors.initials: RL
authors.lastname: Gibson
authors.forename: T A
authors.initials: TA
authors.lastname: Standaert
authors.forename: D E
authors.initials: DE
authors.lastname: Woodrum
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D001784:Blood Gas Analysis; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003964:Diaphragm / Q000098:blood supply / Q000503:physiopathology*; D004558:Electric Stimulation; D005231:Fatty Acids, Unsaturated; D006439:Hemodynamics / Q000187:drug effects; D006834:Hydrazines / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D011312:Pressure; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011659:Pulmonary Gas Exchange / Q000187:drug effects / Q000502:physiology; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology; D013290:Streptococcal Infections / Q000503:physiopathology*; D013292:Streptococcus agalactiae; D013552:Swine; D013928:Thromboxane A2 / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D011450:Prostaglandin Endoperoxides, Synthetic; D017482:Receptors, Thromboxane; D014662:Vasoconstrictor Agents; D013928:Thromboxane A2; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C045749:SQ 29548; D007213:Indomethacin