Hypoxic Pulmonary Vasoconstriction in Humans

Ariyaratnam, Priyadharshanan; Loubani, Mahmoud; Morice, Alyn H.

doi:10.1155/2013/623684

Cited by 17 publications

(20 citation statements)

References 45 publications

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“…Electrical coupling of GJs in the VSMCs serves a crucial role in the synchronization and coordination of vasomotor tone (9). Ischemia or hypoxia can cause systemic vascular system relaxation with the exception of the pulmonary artery (6,46). Following exposure to hypoxic conditions, the cardiomyocytes shorten to reduce contraction and increase the resistance of the whole tissue (17,47).…”

Section: Discussionmentioning

confidence: 99%

“…Reduced or impaired blood flow patterns in the larger conductance and resistance arteries are a factor in numerous pathological conditions that are associated with hypoxia-induced injury (2)(3)(4). It is known that acute hypoxia is associated with a number of cardiovascular diseases, including myocardial infarction (5), pulmonary hypertension (6,7) and mesenteric ischemia (8) and thus leads to an increase in blood pressure together with peripheral vascular resistance due to reduction of tone in certain vascular beds and critical injury or death (4).…”

Section: Introductionmentioning

confidence: 99%

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Role of gap junctions in the contractile response to agonists in the mesenteric resistance artery of rats with acute hypoxia

Liu

Peng

et al. 2017

Molecular Medicine Reports

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Hypoxic exposure results in the vascular dysfunction and reduction of vasomotor responses and thus disrupts or reduces blood flow in the resistance arteries. Connexin (Cx)-mediated gap junctional intercellular communication (GJIC) serves a critical role in the regulation of vasomotor tone and the synchronized contraction of arteries, however whether the adverse effect of hypoxia on vasomotor responses in vascular smooth muscle layer of resistance arteries is involved in changes in the GJIC and the expression of Cx43 and Cx45 remains to be elucidated. Pressure myography, whole-cell patch clamp and western blot analysis were used to investigate the differences in expression and function of gap junction (GJ) in the vascular smooth muscle cells (VSMCs) of the mesenteric resistance artery (MRA) from Sprague‑Dawley (SD) rats in normoxia and acute hypoxia groups. In the present study, whole‑cell patch clamp measurements demonstrated a signiﬁcant reduction in the membrane capacitance and conductance in the VSMCs of the MRAs in the acute hypoxia (5 min) group (n=13) compared with the normoxia group (n=13), which suggested that exposure to acute hypoxia of 5 min decreased the coupling of the GJ between the VSMCs of MRAs in SD rats. Pressure myographic analysis demonstrated that 0.1‑100 µM phenylephrine (PE)‑induced MRA vasoconstriction was less sensitive under the acute hypoxic condition (n=7) compared with the normoxia condition (n=9) following treatment with 100 µM 2‑aminoethoxydiphenyl borate for 20 min. Compared with SD rats under normoxia, the PE‑initiated vasoconstrictive frequency and amplitude under acute hypoxia for 20, 40 and 60 min in the MRAs of SD rats was markedly attenuated (n=7). The results of western blot analysis indicated that the expression levels of Cx43 and Cx45 in MRA under acute hypoxia (1 h) were lower compared with normoxia. Cx43‑and Cx45‑mediated GJs serve a signiﬁcant role in the regulation of the vasomotor function of MRA during hypoxia and may be essential for the adjustment of vasomotor tone in response to acute hypoxia.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Role of gap junctions in the contractile response to agonists in the mesenteric resistance artery of rats with acute hypoxia

Liu

Peng

et al. 2017

Molecular Medicine Reports

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“…This recruitment would result from hypoxic pulmonary vasoconstriction – the theory to explain the blood flow redistribution in response to hypoxia. 24 In a sitting position, when spirometry is performed, the upper lobes show a low blood flow as compared with the lower lobes, due to gravitational differences within the lung, 19 but this gradient of perfusion could be altered by hypoxic pulmonary vasoconstriction. We presumed blood flow redistribution was effective when lower lobes were hypoxic but wasn’t effective enough when upper lobes were hypoxic since lower lobes would already be well perfused.…”

Section: Discussionmentioning

confidence: 99%

Lobar analysis of collapsibility indices to assess functional lung volumes in COPD patients

Kitano

Iwano

Hashimoto

et al. 2014

COPD

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BackgroundWe investigated correlations between lung volume collapsibility indices and pulmonary function test (PFT) results and assessed lobar differences in chronic obstructive pulmonary disease (COPD) patients, using paired inspiratory and expiratory three dimensional (3D) computed tomography (CT) images.MethodsWe retrospectively assessed 28 COPD patients who underwent paired inspiratory and expiratory CT and PFT exams on the same day. A computer-aided diagnostic system calculated total lobar volume and emphysematous lobar volume (ELV). Normal lobar volume (NLV) was determined by subtracting ELV from total lobar volume, both for inspiratory phase (NLVI) and for expiratory phase (NLVE). We also determined lobar collapsibility indices: NLV collapsibility ratio (NLVCR) (%) = (1 − NLVE/NLVI) × 100%. Associations between lobar volumes and PFT results, and collapsibility indices and PFT results were determined by Pearson correlation analysis.ResultsNLVCR values were significantly correlated with PFT results. Forced expiratory volume in 1 second, measured as percent of predicted results (FEV1%P) was significantly correlated with NLVCR values for the lower lobes (P<0.01), whereas this correlation was not significant for the upper lobes (P=0.05). FEV1%P results were also moderately correlated with inspiratory, expiratory ELV (ELVI,E) for the lower lobes (P<0.05). In contrast, the ratio of the diffusion capacity for carbon monoxide to alveolar gas volume, measured as percent of predicted (DLCO/VA%P) results were strongly correlated with ELVI for the upper lobes (P<0.001), whereas this correlation with NLVCR values was weaker for upper lobes (P<0.01) and was not significant for the lower lobes (P=0.26).ConclusionFEV1%P results were correlated with NLV collapsibility indices for lower lobes, whereas DLCO/VA%P results were correlated with NLV collapsibility indices and ELV for upper lobes. Thus, evaluating lobar NLV collapsibility might be useful for estimating pulmonary function in COPD patients.

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“…Later, VON EULER and LILJESTRAND [18] suggested in 1946 that HPV serves for ventilation-perfusion matching in response to alveolar hypoxia. Shortly thereafter, in 1947, HPV was demonstrated to be also present in humans [19,20]. Some decades ago, it became clear that HPV is primarily achieved by vasoconstriction of the pre-capillary pulmonary vessels, located at the entrance of the acinus, and to a lesser degree by post-capillary-located venules [21][22][23][24].…”

Section: Characteristics Of Hpvmentioning

confidence: 99%

Oxygen sensing and signal transduction in hypoxic pulmonary vasoconstriction

et al. 2015

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Number 11 in the series "Physiology in respiratory medicine" Edited by R. Naeije, D. Chemla, A. Vonk-Noordegraaf and A.T. Dinh-Xuan Affiliation: Excellence Cluster Cardiopulmonary System, University of Giessen Lung Center, German Center for Lung Research (DZL), Justus-Liebig-University, Giessen, Germany.Correspondence: Norbert Weissmann, Excellence Cluster Cardiopulmonary System, University of Giessen Lung Center, German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany. E-mail: Norbert.Weissmann@innere.med.uni-giessen.de ABSTRACT Hypoxic pulmonary vasoconstriction (HPV), also known as the von Euler-Liljestrand mechanism, is an essential response of the pulmonary vasculature to acute and sustained alveolar hypoxia. During local alveolar hypoxia, HPV matches perfusion to ventilation to maintain optimal arterial oxygenation. In contrast, during global alveolar hypoxia, HPV leads to pulmonary hypertension. The oxygen sensing and signal transduction machinery is located in the pulmonary arterial smooth muscle cells (PASMCs) of the pre-capillary vessels, albeit the physiological response may be modulated in vivo by the endothelium. While factors such as nitric oxide modulate HPV, reactive oxygen species (ROS) have been suggested to act as essential mediators in HPV. ROS may originate from mitochondria and/or NADPH oxidases but the exact oxygen sensing mechanisms, as well as the question of whether increased or decreased ROS cause HPV, are under debate. ROS may induce intracellular calcium increase and subsequent contraction of PASMCs via direct or indirect interactions with protein kinases, phospholipases, sarcoplasmic calcium channels, transient receptor potential channels, voltage-dependent potassium channels and L-type calcium channels, whose relevance may vary under different experimental conditions. Successful identification of factors regulating HPV may allow development of novel therapeutic approaches for conditions of disturbed HPV. @ERSpublications ROS originating from mitochondria and/or NADPH oxidases may initiate HPV but exact signalling mechanisms are unclear http://ow.ly/SkaGC

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Hypoxic Pulmonary Vasoconstriction in Humans

Cited by 17 publications

References 45 publications

Role of gap junctions in the contractile response to agonists in the mesenteric resistance artery of rats with acute hypoxia

Role of gap junctions in the contractile response to agonists in the mesenteric resistance artery of rats with acute hypoxia

Lobar analysis of collapsibility indices to assess functional lung volumes in COPD patients

Oxygen sensing and signal transduction in hypoxic pulmonary vasoconstriction

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