Although nitric oxide (NO) from inducible nitric oxide synthase (NOSII) is proposed to be the major factor in the vascular abnormalities of sepsis in rats, its role in higher order species is not well established. This thesis thus, addresses the role of NO in septic pigs. / I first hypothesized that induction of NOSII in pigs is the cause of sepsis-induced hypotension as occurs in rodents. To test this, I treated pigs with lipopolysaccharide (LPS) to simulate sepsis. In contrast to what is observed in rats and mice, plasma nitrite did not change during the 4 hours of the LPS infusion and there was no increase in calcium (Ca)-independent nitric oxide synthase (NOS) activity in lung tissue from endotoxemic pigs compared to control animals. Furthermore, there was only minimal induction of NOSII mRNA. / My second hypothesis was that NOS (NOSIII) is not down regulated in septic pigs, and NO from NOSIII, could contribute to peroxynitrite formation. In support of this, western blot analysis of samples from aorta and vena cava showed no down regulation of NOSIII. There also was an increase in Ca ++-dependent NOS activity of aorta and vena cava after 2-hour of endotoxemia, which indicates increased constitutive NOS activity. Moreover, there was an increase in NOSI in the vena cava. LPS produced a leftward shift in the dose-response curves of SVR and RVR in response to the NOS inhibitor, L-NAME (NG -nitro-L-arginine-methyl-ester). / Peroxynitrite is formed from NO and superoxide (O2 -). Since NO was not increased in endotoxemic pigs, I next hypothesized that O2- is increased in endotoxemic pigs and this reacts with NO from constitutive NOS to form peroxynitrite. To test this hypothesis, I first studied rats to confirm that O2 - is increased in arterial vessels of endotoxic rats. There was a small increase in basal O2- in endotoxic rats. Stimulation of NAD(P)H oxidase by giving the substrate, NADH, did not result in different O2- production in control and endotoxic rats. However, inhibition of NOS increased O2 - in endotoxic rats. / I demonstrated by immunohistochemistry and western blot analysis, that the components of NAD(P)H oxidase, gp91phox, p22phox , and p47phox are present in skeletal muscle and it has similar behavior to other non-phagocytic NADPH oxidases. The addition of L-NAME to NADH-treated diaphragm strips of endotoxic rats, increased O 2- production in endotoxic rats indicating that O2- production counters the increased NO formation as we observed in rat aorta. These observations indicate that O2 - generation from NADPH oxidase in skeletal muscles can play a role in the pathophysiology of sepsis. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36960 |
| Date | January 2000 |
| Creators | Javeshghani, Danesh. |
| Contributors | Magder, Sheldon (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Physiology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001804003, proquestno: NQ70051, Theses scanned by UMI/ProQuest. |
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