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  • 1
    Online Resource
    Online Resource
    Elsevier BV ; 1983
    In:  Acta Histochemica Vol. 73, No. 2 ( 1983-1), p. 259-271
    In: Acta Histochemica, Elsevier BV, Vol. 73, No. 2 ( 1983-1), p. 259-271
    Type of Medium: Online Resource
    ISSN: 0065-1281
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1983
    detail.hit.zdb_id: 2038464-6
    SSG: 12
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  • 2
    In: Cell, Elsevier BV, Vol. 31, No. 1 ( 1982-11), p. 43-51
    Type of Medium: Online Resource
    ISSN: 0092-8674
    RVK:
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1982
    detail.hit.zdb_id: 187009-9
    detail.hit.zdb_id: 2001951-8
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    American Physiological Society ; 1984
    In:  Journal of Applied Physiology Vol. 56, No. 5 ( 1984-05-01), p. 1340-1346
    In: Journal of Applied Physiology, American Physiological Society, Vol. 56, No. 5 ( 1984-05-01), p. 1340-1346
    Abstract: We hypothesized that leukotrienes are involved in hypoxic pulmonary vasoconstriction, since they are pulmonary vasoconstrictors and cells capable of producing leukotrienes are located in the lung near resistance vessels. We investigated in isolated perfused rat lungs whether three structurally unrelated blockers [diethylcarbamazine citrate (DEC), U-60257, and FPL 55712] of leukotriene synthesis or action block hypoxic pulmonary vasoconstriction. DEC blocked ongoing and subsequent hypoxic pressor responses while minimally affecting the angiotensin II pressor response. The inhibition of the hypoxic pressor response by DEC was not affected by cyclooxygenase or H1-receptor blockers. Potassium-induced vasoconstriction, which is dependent on calcium entry, was largely blocked by verapamil but not by DEC, suggesting that DEC was not acting primarily as a calcium-entry blocker. U-60257 blocked the hypoxic pressor response without inhibiting the pressor response to angiotensin II or potassium chloride. FPL 55712, a leukotriene end-organ blocker, in a dose which inhibited vasoconstriction caused by exogenous leukotriene C4, inhibited the pressor response to hypoxia but not to angiotensin II. We conclude that leukotriene inhibitors preferentially inhibit hypoxic pulmonary vasoconstriction in isolated perfused adult rat lungs.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1984
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 4
    Online Resource
    Online Resource
    American Physiological Society ; 1984
    In:  Journal of Applied Physiology Vol. 57, No. 2 ( 1984-08-01), p. 388-395
    In: Journal of Applied Physiology, American Physiological Society, Vol. 57, No. 2 ( 1984-08-01), p. 388-395
    Abstract: Because deformation of lung tissue stimulates prostaglandin synthesis, we wanted to investigate whether hydrodynamic forces would affect lung prostacyclin (PGI2) production. To test the hypothesis that lung prostacyclin synthesis was flow dependent, we examined lung prostacyclin production after flow alterations. Using a salt solution that contained either Ficoll or albumin as a perfusate, we changed the flow to half and to double the control flow. When flow was changed, lung prostacyclin production followed changes in flow and pressure drop. When flow was varied in lungs treated with indomethacin, prostacyclin production was too low to be measurable. Variations in pressure pulsatility at constant mean flow had no influence on lung prostacyclin production. Since vascular distension may also stimulate prostacyclin production, we increased venous pressure. An increase in venous pressure (from 2.1 to 4.8 mmHg) had no effect on prostacyclin production; a further increase in venous pressure (to 7.5 mmHg) initiated edema and caused a large increase in prostacyclin production. When we subjected monolayers of endothelial cells cultured in wells to defined shear rates, the prostacyclin concentration in the supernatant quickly increased to a maximum. The absence of further increase with greater shear may have reflected feedback control of prostacyclin synthesis. The results indicated that hydrodynamic disturbances affect endothelial cells and stimulate arachidonate metabolism. Lung prostacyclin production may be related to flow. However, this effect is small compared with the lung prostacyclin production during edema formation.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1984
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 5
    Online Resource
    Online Resource
    American Physiological Society ; 1984
    In:  Journal of Applied Physiology Vol. 56, No. 4 ( 1984-04-01), p. 900-905
    In: Journal of Applied Physiology, American Physiological Society, Vol. 56, No. 4 ( 1984-04-01), p. 900-905
    Abstract: Active oxygen species can cause lung injury. Although a direct action on endothelial cells is proposed, the possibility exists that they might cause injury via mediators. We considered that active oxygen species would stimulate the generation of cyclooxygenase metabolites, which then alter pulmonary vasoreactivity and cause edema. We chemically produced hydrogen peroxide by adding glucose oxidase to a plasma- and cell-free, but beta-D-glucose-containing, solution, which perfused isolated rat lungs. Addition of glucose oxidase to the perfusate caused a marked decrease in pulmonary vasoreactivity, accompanied by an increase in the concentrations of prostacyclin, thromboxane A2, and prostaglandin F2 alpha. Pretreatment with catalase, a specific scavenger of hydrogen peroxide, preserved pulmonary vasoreactivity, inhibited the increase of the concentration of the measured prostaglandins, and prevented edema formation. Indomethacin effectively blocked lung prostaglandin production but neither prevented the decrease in vasoreactivity nor inhibited edema formation. From these data we conclude that hydrogen peroxide impaired pulmonary vasoreactivity and subsequently caused edema. Despite the fact that hydrogen peroxide stimulated lung prostaglandin production, cyclooxygenase-derived products neither caused the decrease in vasoreactivity nor the development of edema.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1984
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 6
    Online Resource
    Online Resource
    American Physiological Society ; 1982
    In:  Journal of Applied Physiology Vol. 52, No. 6 ( 1982-06-01), p. 1571-1574
    In: Journal of Applied Physiology, American Physiological Society, Vol. 52, No. 6 ( 1982-06-01), p. 1571-1574
    Abstract: Many mammals exhibit elevated pulmonary arterial pressure when exposed to airway hypoxia. In addition, prolonged hypoxic exposure may result in elevated hematocrit and right ventricular hypertrophy. The current study was designed to test whether the hamster, a fossorial species, may possess naturally selected physiological characteristics advantageous to a chronically hypoxic environment. Hamsters and rats were studied at low altitude (1,520 m) and after 5 wk at high altitude (4,250 m). Hematocrit for low-altitude hamsters was 53 +/- 1 compared with 45 +/- 1 for low-altitude rats. Low-altitude hamsters and rats demonstrated the same right ventricular weight-to-total ventricular weight ratio (RV/T) (0.223 +/- 0.006 vs. 0.222 +/- 0.003). After high-altitude exposure the hematocrit for hamsters and rats was the same (58 +/- 1 vs. 57 +/- 1), but RV/T was less in the hamster (0.251 +/- 0.004 vs. 0.288 +/- 0.005). In addition, the hypoxic pulmonary pressor response of lungs isolated from low- and high-altitude animals was examined. Lungs from hamsters were less responsive than lungs from rats at all levels of hypoxia tested. In addition, exposure to altitude resulted in a diminished pressor response in lungs from both species. It is concluded that the pulmonary vasculature of the hamster is less responsive to hypoxia than that of the rat, and that this relative unresponsiveness may aid the hamster in an hypoxic environment.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1982
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 7
    Online Resource
    Online Resource
    American Physiological Society ; 1981
    In:  Journal of Applied Physiology Vol. 50, No. 2 ( 1981-02-01), p. 363-366
    In: Journal of Applied Physiology, American Physiological Society, Vol. 50, No. 2 ( 1981-02-01), p. 363-366
    Abstract: Exposure to chronic hypoxia results in a lower resting heart rate and a blunted cardiovascular responsiveness to beta-adrenergic receptor stimulation. Possible effects of acclimatization to high altitude on the binding of [125I]iodohydroxybenzylpindolol to beta-adrenergic receptors on membranes of right and left ventricles of rat heart were determined. Chronic high-altitude exposure led to a decrease in the density of beta-adrenergic receptors in nonhypertrophied left ventricles as well as in hypertrophied right ventricles. The affinity of the receptor for the radioligand was not changed by the exposure to high altitude, suggesting that the properties of the receptor were not affected. Basal and isoproterenol-stimulated adenylate cyclase activities were decreased in membranes prepared from hearts and pulmonary arteries of rats acclimatized to high altitude. The loss of cardiac beta-adrenergic receptors in rats adapted to high altitude was prevented by the chronic coadministration of a low dose of DL-propranolol. The results suggest that changes in beta-adrenergic receptor density may partially explain the hemodynamic adaptation that occurs with chronic hypoxia. These decreases may be due to a loss of functional beta-adrenergic receptors caused by chronically elevated concentrations of circulating neurally released catecholamines.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1981
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 8
    Online Resource
    Online Resource
    American Association for the Advancement of Science (AAAS) ; 1982
    In:  Science Vol. 218, No. 4569 ( 1982-10-15), p. 286-289
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 218, No. 4569 ( 1982-10-15), p. 286-289
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
    RVK:
    RVK:
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 1982
    detail.hit.zdb_id: 128410-1
    detail.hit.zdb_id: 2066996-3
    detail.hit.zdb_id: 2060783-0
    SSG: 11
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  • 9
    Online Resource
    Online Resource
    American Physiological Society ; 1980
    In:  Journal of Applied Physiology Vol. 48, No. 3 ( 1980-03-01), p. 473-478
    In: Journal of Applied Physiology, American Physiological Society, Vol. 48, No. 3 ( 1980-03-01), p. 473-478
    Abstract: Chronic beta-receptor blockade has been reported to inhibit right ventricular hypertrophy in rats at high altitude. If so, we wanted to determine whether beta-receptor blockade or some other drug action were involved and whether the heart, the lung vessels, or blood alterations were affected. In rats, chronic treatment with DL-propranolol (2 mg/kg ip once daily) reduced right ventricular hypertrophy and polycythemia of chronic high altitude. D-Propranolol and metoprolol did not reduce hypoxia-induced right ventricular hypertrophy or polycythemia. In isolated lungs from low-altitude rats treated chronically with DL-propranolol or with D-propranolol the pressor response to acute hypoxia was blunted. Chronic DL-propranolol blunted the acute hypoxic pressor response and angiotensin II induced vasoconstriction in lungs from high-altitude rats. Two effects of DL-propranolol treatment were seen: 1) blockade of beta 2-adrenergic receptors, which reduced the right ventricular hypertrophy of high altitude through reduction of hematocrit; and 2) a non-beta-effect, which reduced vascular responsiveness to acute hypoxia in the isolated lung preparation.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1980
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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  • 10
    Online Resource
    Online Resource
    American Physiological Society ; 1982
    In:  Journal of Applied Physiology Vol. 52, No. 3 ( 1982-03-01), p. 705-709
    In: Journal of Applied Physiology, American Physiological Society, Vol. 52, No. 3 ( 1982-03-01), p. 705-709
    Abstract: Recent studies have shown that vasodilator prostaglandins are continually produced by the isolated rat lung. We postulated that these vasodilators may contribute to maintenance of normal low pulmonary arterial pressure. Pulmonary pressure and cardiac output were measured in conscious dogs prior to and 30 to 60 min following administration of meclofenamate (2 mg/kg iv, followed by infusion at 2 mg . kg-1 . h-1) or the structurally dissimilar inhibitor RO–20–5720 (1 mg/kg iv, followed by infusion at 1 mg . kg-1 . h-1). The animals were also made hypoxic with inhalation of 10% O2 before and after inhibition. Time-control experiments were conducted in which only the saline vehicle was administered. Meclofenamate or RO–20–5720 caused an increase in mean pulmonary arterial pressure and total pulmonary resistance. Cardiac output and systemic pressure were unaffected. The mild hypoxic pulmonary pressor response observed was not affected by meclofenamate. Animals breathing 30% O2 to offset Denver's altitude also demonstrated increased pulmonary pressure and resistance when given meclofenamate. It is concluded that endogenous vasodilator prostaglandins may contribute to normal, low vascular tone in the pulmonary circulation.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    RVK:
    RVK:
    Language: English
    Publisher: American Physiological Society
    Publication Date: 1982
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
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