Physiology - Journal Articles
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Item The ups and downs of intermittent hypoxia as a therapy for ventilatory insufficiency(John Wiley and Sons Inc, 2022) O'Halloran, Ken D.; Science Foundation IrelandItem Endogenous medullary raphé hydrogen sulphide facilitates the ventilatory response to hypercapnia(John Wiley and Sons Inc, 2021) Condon-English, Finbarr J.; O'Halloran, Ken D.Item Prebiotic administration modulates gut microbiota and faecal short-chain fatty acid concentrations but does not prevent chronic intermittent hypoxia-induced apnoea and hypertension in adult rats(Elsevier, 2020) O'Connor, Karen M.; Lucking, Eric F.; Bastiaanssen, Thomaz F. S.; Peterson, Veronica L.; Crispie, Fiona; Cotter, Paul D.; Clarke, Gerard; Cryan, John F.; O'Halloran, Ken D.; Science Foundation IrelandBackground: Evidence is accruing to suggest that microbiota-gut-brain signalling plays a regulatory role in cardiorespiratory physiology. Chronic intermittent hypoxia (CIH), modelling human sleep apnoea, affects gut microbiota composition and elicits cardiorespiratory morbidity. We investigated if treatment with prebiotics ameliorates cardiorespiratory dysfunction in CIH-exposed rats. Methods: Adult male rats were exposed to CIH (96 cycles/day, 6.0% O2 at nadir) for 14 consecutive days with and without prebiotic supplementation (fructo- and galacto-oligosaccharides) beginning two weeks prior to gas exposures. Findings: CIH increased apnoea index and caused hypertension. CIH exposure had modest effects on the gut microbiota, decreasing the relative abundance of Lactobacilli species, but had no effect on microbial functional characteristics. Faecal short-chain fatty acid (SCFA) concentrations, plasma and brainstem pro-inflammatory cytokine concentrations and brainstem neurochemistry were unaffected by exposure to CIH. Prebiotic administration modulated gut microbiota composition and diversity, altering gut-metabolic (GMMs) and gut-brain (GBMs) modules and increased faecal acetic and propionic acid concentrations, but did not prevent adverse CIH-induced cardiorespiratory phenotypes. Interpretation: CIH-induced cardiorespiratory dysfunction is not dependant upon changes in microbial functional characteristics and decreased faecal SCFA concentrations. Prebiotic-related modulation of microbial function and resultant increases in faecal SCFAs were not sufficient to prevent CIH-induced apnoea and hypertension in our model. Our results do not exclude the potential for microbiota-gut-brain axis involvement in OSA-related cardiorespiratory morbidity, but they demonstrate that in a relatively mild model of CIH, sufficient to evoke classic cardiorespiratory dysfunction, such changes are not obligatory for the development of morbidity, but may become relevant in the elaboration and maintenance of cardiorespiratory morbidity with progressive disease. Funding: Department of Physiology and APC Microbiome Ireland, University College Cork, Ireland. APC Microbiome Ireland is funded byScience Foundation Ireland, through the Government’s National Development Plan.Item Swallow-breathing coordination during incremental ascent to altitude(Elsevier B.V., 2019) Huff, Alyssa; Day, Trevor A.; English, Mason; Reed, Mitchell D.; Zouboules, Shaelynn; Saran, Gurkarn; Leacy, Jack K.; Mann, Carli; Peltonen, Joel D. B.; O'Halloran, Ken D.; Sherpa, Mingma T.; Pitts, Teresa; National Institutes of Health; Kentucky Spinal Cord and Head Injury Trust; University of Louisville; Natural Sciences and Engineering Research Council of CanadaSwallow and breathing are highly coordinated behaviors reliant on shared anatomical space and neural pathways. Incremental ascent to high altitudes results in hypoxia/hypocapnic conditions altering respiratory drive, however it is not known whether these changes also alter swallow. We examined the effect of incremental ascent (1045 m, 3440 m and 4371 m) on swallow motor pattern and swallow-breathing coordination in seven healthy adults. Submental surface electromyograms (sEMG) and spirometry were used to evaluate swallow triggered by saliva and water infusion. Swallow-breathing phase preference was different between swallows initiated by saliva versus water. With ascent, saliva swallows changed to a dominate pattern of occurrence during the transition from inspiration to expiration. Additionally, water swallows demonstrated a significant decrease in submental sEMG duration and a shift in submental activity to earlier in the apnea period, especially at 4371 m. Our results suggest that there are changes in swallow-breathing coordination and swallow production that likely increase airway protection with incremental ascent to high altitude. The adaptive changes in swallow were likely due to the exposure to hypoxia and hypocapnia, along with airway irritation. © 2018 Elsevier B.V.Item Physiological bioactivity of a postbiotic consisting of heat-treated lactobacilli on mouse small intestine(Elsevier, 2023-08-16) Uhlig, Friederike; Warda, Alicja K.; Hueston, Cara M.; Draper, Lorraine A.; Chauvière, Gilles; Eckhardt, Erik; Hill, Colin; Hyland, Niall P.Lactobacillus LB is a postbiotic generated following fermentation by Limosilactobacillus fermentum and Lactobacillus delbrueckii. Lactobacillus LB alleviates acute diarrhoea and ameliorates the symptoms of irritable bowel syndrome. Here, we investigated whether modulation of intestinal ion transport and motility contributes to these beneficial effects and whether the postbiotic produced with both strains contributes to a unique biophysiological profile. In Ussing chamber studies, low lactose-Lactobacillus LB (LL-LB) significantly increased baseline short-circuit current, and this was partially mediated by sodium-D-glucose transporter 1. In organ baths, LL-LB significantly decreased ileal tone and increased carbachol-induced contractility. Relative to LL-LB, preparations produced using a single strain fermentate generated from L. fermentum significantly increased baseline short-circuit current and inhibited carbachol-induced contractility. Our data demonstrate a unique biophysiological profile for the dual strain postbiotic and support a direct and immediate effect of LL-LB on host physiology ex vivo which could contribute to the clinical efficacy of Lactobacillus LB.