Sensitivity of Rabbit Aorta to Altered Oxygen Tension

Pittman, Roland N.; Graham, Barbara A.

doi:10.1007/978-1-4684-5188-7_46

Cited by 2 publications

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“…After isolation, the blood vessels in some studies spontaneously developed tone [ 13 , 16 , 18 , 31 , 46 – 50 ]. Isolated vessels that did not develop tone were left unconstricted [ 17 , 51 – 53 ] or were constricted to ~ 40–50% of their baseline diameter with norepinephrine [ 16 , 54 , 55 ], phenylephrine [ 56 ], histamine [ 15 ], potassium chloride [ 15 , 18 , 55 ], thromboxane (U46199) [ 53 ], serotonin (5-HT) [ 53 ] or prostaglandin F2α [ 53 ]. Vessels were exposed to normoxia by gassing the surrounding buffer with 10–21% oxygen.…”

Section: Resultsmentioning

confidence: 99%

“…Of the ex vivo studies, eight studies used a total of three [ 18 , 31 , 47 , 49 ], four [ 16 , 50 , 70 ] or five [ 55 ] oxygen concentrations (including reference level). The range of oxygen exposure assessed varied between 10 and 21% to 10–95%.…”

Section: Resultsmentioning

confidence: 99%

“…In all studies except for two, a decrease in diameter was seen as the oxygen concentration increased. The dose-response relationships in studies with more than three levels of exposure were described as linear in the normoxic-hyperoxic range [ 16 , 55 , 70 , 71 ]. In one study there was no discernable difference between 40% or 95% O 2 [ 18 ] and in another there was no effect at any oxygen concentration (10–95% O 2 ) [ 16 ].…”

Section: Resultsmentioning

confidence: 99%

“…Out of the 23 experiments, 18 (k = 18) were included in the meta-analysis of ex vivo studies. Four experiments were mentioned in the text but were not accompanied by data [ 15 , 53 , 55 ] and one paper reported normalized data for one experiment that could not be appropriately recalculated [ 31 ]. Overall, there was a borderline significant vasoconstrictor effect of hyperoxia on arteries ex vivo (SMD − 0.56 (− 1.09 to − 0.03), P = 0.04, Fig.…”

Section: Resultsmentioning

confidence: 99%

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Effects of hyperoxia on vascular tone in animal models: systematic review and meta-analysis

et al. 2018

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BackgroundArterial hyperoxia may induce vasoconstriction and reduce cardiac output, which is particularly undesirable in patients who already have compromised perfusion of vital organs. Due to the inaccessibility of vital organs in humans, vasoconstrictive effects of hyperoxia have primarily been studied in animal models. However, the results of these studies vary substantially. Here, we investigate the variation in magnitude of the hyperoxia effect among studies and explore possible sources of heterogeneity, such as vascular region and animal species.MethodPubmed and Embase were searched for eligible studies up to November 2017. In vivo and ex vivo animal studies reporting on vascular tone changes induced by local or systemic normobaric hyperoxia were included. Experiments with co-interventions (e.g. disease or endothelium removal) or studies focusing on lung, brain or fetal vasculature or the ductus arteriosus were not included. We extracted data pertaining to species, vascular region, blood vessel characteristics and method of hyperoxia induction. Overall effect sizes were estimated with a standardized mean difference (SMD) random effects model.ResultsWe identified a total of 60 studies, which reported data on 67 in vivo and 18 ex vivo experiments. In the in vivo studies, hyperoxia caused vasoconstriction with an SMD of − 1.42 (95% CI − 1.65 to − 1.19). Ex vivo, the overall effect size was SMD − 0.56 (95% CI − 1.09 to − 0.03). Between-study heterogeneity (I2) was high for in vivo (72%, 95% CI 62 to 85%) and ex vivo studies (86%, 95% CI 78 to 98%). In vivo, in comparison to the overall effect size, hyperoxic vasoconstriction was less pronounced in the intestines and skin (P = 0.03) but enhanced in the cremaster muscle region (P < 0.001). Increased constriction was seen in vessels 15–25 μm in diameter. Hyperoxic constriction appeared to be directly proportional to oxygen concentration. For ex vivo studies, heterogeneity could not be explained with subgroup analysis.ConclusionThe effect of hyperoxia on vascular tone is substantially higher in vivo than ex vivo. The magnitude of the constriction is most pronounced in vessels ~ 15–25 μm in diameter and is proportional to the level of hyperoxia. Relatively increased constriction was seen in muscle vasculature, while reduced constriction was seen in the skin and intestines.Electronic supplementary materialThe online version of this article (10.1186/s13054-018-2123-9) contains supplementary material, which is available to authorized users.

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