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- Halim, Md Abdul, 1983-, et al.
(författare)
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Nitric oxide regulation of migrating motor complex : randomised trial of L-NMMA effects in relation to muscarinic and serotonergic receptor blockade
- 2015
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 215:2, s. 105-118
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Tidskriftsartikel (refereegranskat)abstract
- AimThe migrating motor complex (MMC) propels contents through the gastrointestinal tract during fasting. Nitric oxide (NO) is an inhibitory neurotransmitter in the gastrointestinal tract. Little is known about how NO regulates the MMC. In this study, the aim was to examine nitrergic inhibition of the MMC in man using NG-monomethyl-l-arginine (l-NMMA) in combination with muscarinic receptor antagonist atropine and 5-HT3 receptor antagonist ondansetron.MethodsTwenty-six healthy volunteers underwent antroduodenojejunal manometry for 8 h with saline or NO synthase (NOS) inhibitor l-NMMA randomly injected I.V. at 4 h with or without atropine or ondansetron. Plasma ghrelin, motilin and somatostatin were measured by ELISA. Intestinal muscle strip contractions were investigated for NO-dependent mechanisms using l-NMMA and tetrodotoxin. NOS expression was localized by immunohistochemistry.Resultsl-NMMA elicited premature duodenojejunal phase III in all subjects but one, irrespective of atropine or ondansetron. l-NMMA shortened MMC cycle length, suppressed phase I and shifted motility towards phase II. Pre-treatment with atropine extended phase II, while ondansetron had no effect. l-NMMA did not change circulating ghrelin, motilin or somatostatin. Intestinal contractions were stimulated byl-NMMA, insensitive to tetrodotoxin. NOS immunoreactivity was detected in the myenteric plexus but not in smooth muscle cells.ConclusionNitric oxide suppresses phase III of MMC independent of muscarinic and 5-HT3 receptors as shown by nitrergic blockade, and acts through a neurocrine disinhibition step resulting in stimulated phase III of MMC independent of cholinergic or 5-HT3-ergic mechanisms. Furthermore, phase II of MMC is governed by inhibitory nitrergic and excitatory cholinergic, but not 5-HT3-ergic mechanisms.
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| 2. |
- Hellström, Per M., 1954-, et al.
(författare)
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Luminal Nitric Oxide and Plasma Nitrite/Nitrate As Predictors of Colectomy in Corticosteroid-Treated Acute Colitis
- 2015
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Ingår i: Gastroenterology. - Uppsala. - 0016-5085 .- 1528-0012. ; 148:4, suppl. 1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Nitric oxide (NO) is known to be up-regulated by the induction of induciblenitric oxide synthase (iNOS) in inflammatory conditions. NO gas can be used as a markerof inflammatory activity in hollow organs. In parallel, plasma nitrite + nitrate (NOx) canreflect the ongoing inflammatory activity. We analyzed rectal NO before and after threedays, as well as plasma NOx in patients on glucocorticosteroid (GC) therapy in hospitalizedpatients. The aim of the study was to evaluate the relationship of rectal luminal NO andcirculating plasma NOx in acute fulminant colitis to the outcome as therapeutic responseor colectomy.Methods: 50 patients with median age 41 (range 20-78) years were hospitalizeddue to acute fulminant colitis and received treatment with high-dose GCs. Luminal nitricoxide was analyzed with chemiluminescence before therapy onset of therapy with GC andon day 3 of treatment. NOx was measured by nitrite/nitrate colorimetric assay. NO levelsand plasma NOx were compared to clinical disease activity index and C-reactive protein(CRP).Results: 32 responded to GC treatment and 18 did not, resulting in colectomy.The responders had higher luminal NO than non-responders (day 1: 12525±2600, day 3:15590±4157 ppb) vs non-responders (day 1: 2874±1283, day 3: 1137±297 ppb) (p<0.0114).Using an optimal cut-off NO level of 2250 ppb, sensitivity and specificity was 86% and81% for colectomy (p<0.0001). The area under the curve was 0.88 and likelihood ratio4.8. Similarly, plasma NOx was higher in responders vs non-responders (day 1: 6.2±0.3 vs3.9±0.4 umol/L) (p<0.0001). Using plasma NOx, we found a corresponding cut-off at 5umol/L with sensitivity 87% and specificity 87%. The area under the curve was 0.88 andlikelihood ratio 6.7. Luminal NO was also correlated to plasma NOx (r=0.33, p=0.0205).In the responder group, CRP levels decreased (day 1: 22.31±2.95, day 3: 15.69±3.57mg/L), whereas among non-responders CRP levels increased (day 1: 45.83±11.10, day 3:76.35±16.96 mg/L) (p<0.0167). Kaplan-Meier analysis showed that patients with baselineNO levels lower than 2250 ppb were at a significantly higher risk of colectomy within onemonth from onset of GCS treatment (p<0.0001). Twelve out of 18 (67%) in patients withday 1 NO <2250 ppb were colectomized, the corresponding number of patients with NO>2250 ppb was 3 out of 32 (9%). In a similar manner, using plasma NOx <5 uml/L foranalysis, we found 13 (72%) to be colectomized, and with >5 umol/L only two (6%).Conclusion: NO and its oxidation product NOx are markers of inflammatory activity in thegut. However, with more intense inflammation and mucosal damage, the less NO is produced.Luminal NO as well as plasma NOx can be used as a sensitive biomarker to predict colectomyin the outcome of acute fulminant colitis
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