beta-Adrenergic mechanisms attenuated hypoxic pulmonary vasoconstriction during systemic hypoxia in cats

Shirai, Masamitsu; Shindo, Tetsuaki; Ninomiya, Ishio

doi:10.1152/ajpheart.1994.266.5.h1777

Cited by 17 publications

(29 citation statements)

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“…During hypoxia, as PAP increases, vessels larger than 300 -500 m are likely to be subjected to a higher distending pressure (assuming no change in cardiac output), suggesting that constriction of larger vessels (i.e., Ͼ500 m) may be underestimated by a high distending pressure. However, Shirai et al (27) demonstrated that, when the increase in PAP during hypoxia is prevented, the magnitude of vasoconstriction tends to be accentuated, albeit slightly, equally for all pulmonary vessel sizes in the cat.…”

Section: Discussionmentioning

confidence: 99%

“…HPV has been reported to preferentially occur in vessels with an internal diameter of ϳ150 -300 m in cats, and rabbits (10,26,27) and up to Ͻ600 m in dogs (2). During hypoxia, as PAP increases, vessels larger than 300 -500 m are likely to be subjected to a higher distending pressure (assuming no change in cardiac output), suggesting that constriction of larger vessels (i.e., Ͼ500 m) may be underestimated by a high distending pressure.…”

Section: Discussionmentioning

confidence: 99%

“…Several studies have used a severe level of hypoxia (i.e., ϳ8% O 2 ) to elicit significant pulmonary vasoconstriction in the rat, rabbit, and cat (10,21,22,27). In this study, we tested severe hypoxia (8% O 2 ) and moderate hypoxia (10% O 2 ) expecting that the magnitude of pulmonary vasoconstriction may be dependent on the severity of hypoxia.…”

Section: Discussionmentioning

confidence: 99%

“…Yet the vascular responses to 10% and 8% O 2 were similar (assessed by angiography and right ventricular systolic pressure). Shirai et al (27) also assessed the response of the pulmonary vasculature of the cat lung to moderate (10% O 2 ) and severe (5% O 2 ) hypoxia using angiography. They reported that the magnitude of vasoconstriction was greater for 10% O 2 compared with 5% O 2, only if the hypoxia was global (i.e., whole body).…”

Section: Discussionmentioning

confidence: 99%

“…However, conventional angiography systems have considerable limitations in providing images of small blood vessels with diameters of Ͻ200 m in vivo (30, 33). Shirai et al (25) designed a unique X-ray TV system for directly visualizing pulmonary vessels in the cat with diameters 100 -500 m, although such measurements were only possible in open-chest animal models (24,27). In the last decade, technological advances in microangiography have utilized monochromatic synchrotron radiation (SR) as a powerful X-ray source and, when coupled with a high-resolution and high-speed imaging system, provide the ability to study microvessels of various animal organs ex vivo and in vivo (18).…”

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confidence: 99%

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Imaging of the pulmonary circulation in the closed-chest rat using synchrotron radiation microangiography

Schwenke

Pearson²,

Umetani³

et al. 2007

Journal of Applied Physiology

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Schwenke DO, Pearson JT, Umetani K, Kangawa K, Shirai M. Imaging of the pulmonary circulation in the closed-chest rat using synchrotron radiation microangiography. J Appl Physiol 102: [787][788][789][790][791][792][793] 2007. First published October 12, 2006; doi:10.1152/japplphysiol.00596.2006.-Structural changes of the pulmonary circulation during the pathogenesis of pulmonary arterial hypertension remain to be fully elucidated. Although angiography has been used for visualizing the pulmonary circulation, conventional angiography systems have considerable limitations for visualizing small microvessels (diameters Ͻ 200 m), particularly within a closed-chest animal model. In this study we assess the effectiveness of monochromatic synchrotron radiation (SR) for microangiography of the pulmonary circulation in the intact-chest rat. Male adult Sprague-Dawley rats were anesthetized, and a catheter was positioned within the right ventricle, for administering iodinated contrast agent (Iomeron 350). Subsequently, microangiography of pulmonary arterial branches within the left lung was performed using monochromatic SR. Additionally, we assessed dynamic changes in vessel diameter during acute hypoxic (10% and 8% O 2 for 4 min each) pulmonary vasoconstriction (HPV). Using SR we were able to visualize pulmonary microvessels with a diameter of Ͻ100 m (the 4th generation of branching from the left axial artery). Acute hypoxia caused a significant decrease in the diameter of all vessels less than 500 m. The greatest degree of pulmonary vasoconstriction was observed in vessels with a diameter between 200 and 300 m. These results demonstrate the effectiveness of SR for visualizing pulmonary vessels in a closed-chest rat model and for assessing dynamic changes associated with HPV. More importantly, these observations implicate SR as an effective tool in future research for assessing gross structural changes associated with the pathogenesis of pulmonary arterial hypertension. pulmonary microvessels; hypoxia; intact chest STRUCTURAL AND FUNCTIONAL changes of the pulmonary circulation, particularly during the pathogenesis of pulmonary arterial hypertension (PAH), remain to be fully elucidated. Specifically, the small peripheral pulmonary arteries (Ͻ500 m) are believed to be most susceptible to structural changes during, for example, chronic exposure to hypoxia (1,6,7,15,19,32).To date, most small-animal studies that have described the anatomic geometry of the pulmonary circulation have been limited to the use of in vitro or ex vivo preparations. While such data have aided our understanding concerning the pulmonary microcirculation, such invasive procedures ultimately disrupt the natural physiological milieu of the lung. Ideally, a technique of visualizing the pulmonary circulation within a closed-chest model, i.e., under intact neurohumoral regulation, is required to fully understand the structural and functional properties of the microcirculation in the normal lung as well as understand the dynamic changes that occur in pathologic...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Imaging of the pulmonary circulation in the closed-chest rat using synchrotron radiation microangiography

Schwenke

Pearson²,

Umetani³

et al. 2007

Journal of Applied Physiology

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Factors accounting for different responses of pulmonary and cerebral vessels to hypoxia

Di-xun

Xian-rong

Liu

et al. 1996

Journal of Tongji Medical University

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The roles of sympathicus, sensory neuropeptides (SNP), cyclooxygenase metabolites (COX-M), lipoxygenase metabolites (LOX-M), endothelium derived relaxing factor (EDRF), reactive oxygen (ROS) and potassium channels (PC) in the hypoxic pulmonary vasoconstriction (HPV) and hypoxic cerebral vasodilation (HCVD) were investigated in intact rats, rabbits and dogs. The results showed that during hypoxia, the excitation of sympathicus caused a constriction of both pulmonary and cerebral vessels, while SNP, EDRF and the opening of voltage sensitive PC caused the dilation of both of them; LOX-M mediated HPV and HCVD, COX-M might serve as their modulators; the blockade of ATP sensitive PC induced by hypoxia mediated HPV, but had no effect on HCVD; the reduction of O2-. in the lung might potentiate HPV, however, O2-. remained unchanged in brain during hypoxia. It is suggested that the alterations of LOX-M, ROS and the ATP sensitive PC are the factors accounting for the difference in the response of pulmonary and cerebral vessels to hypoxia.

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Possible indications of beta-blockers in the perioperative period other than prevention of cardiac ischemia

Kikuchi

Saito

2010

J Anesth

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According to the guidelines of the American College of Cardiology/American Heart Association 2006 for perioperative cardiovascular evaluation for non-cardiac surgery, beta-blocker therapy should be considered for high-risk individuals undergoing vascular surgery or high- and intermediate-risk patients undergoing non-cardiac surgery. This guideline might induce physicians to increasingly use beta-blockers in the hope of preventing perioperative cardiac complications. However, beta-blockers have potential beneficial effects outside the prevention of cardiac events. In addition to reducing anesthetic and analgesic requirements during the perioperative period, beta-blockers have neuroprotective effects in patients with brain trauma and possible effectiveness in the management of intraoperative awareness-induced post-traumatic stress disorder. Moreover, intrathecal administration of beta-blockers may have antinociceptive effects. Physicians need to bear in mind the benefits of beta-blockers for purposes other than preventing cardiac events when applied in the perioperative period, and they should be familiar with the pharmacodynamics and risk-benefit ratio with their use. This review focuses on possible extracardiac indications of beta-blockers.

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beta-Adrenergic mechanisms attenuated hypoxic pulmonary vasoconstriction during systemic hypoxia in cats

Cited by 17 publications

References 0 publications

Imaging of the pulmonary circulation in the closed-chest rat using synchrotron radiation microangiography

Imaging of the pulmonary circulation in the closed-chest rat using synchrotron radiation microangiography

Factors accounting for different responses of pulmonary and cerebral vessels to hypoxia

Possible indications of beta-blockers in the perioperative period other than prevention of cardiac ischemia

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