To study the effects of alveolar hypoxia on canine bronchopulmonary shunt flow, a biventricular bypass preparation was employed. The preparation allowed a constant and sensitive measure of changes in pulmonary venous blood flow. In 16 of 18 dogs with intact bronchial arteries, alveolar hypoxia caused an increase in pulmonary venous return both under conditions of constant pulmonary arterial inf...

There is evidence that sympathetically evoked vasoconstriction in skeletal muscle is blunted in systemic hypoxia, but the mechanisms underlying this phenomenon are not clear. In Saffan-anaesthetized Wistar rats, we have studied the role of alpha(2)-adrenoceptors and neuropeptide Y (NPY) Y(1) receptors in mediating vasoconstriction evoked by direct stimulation of the lumbar sympathetic chain by ...

Devising therapies that might prevent the onset or progression of pulmonary hypertension in newborns has received little attention. Our major objective was to determine whether sildenafil, a selective phosphodiesterase inhibitor, prevents the development of an early stage of chronic hypoxia-induced pulmonary hypertension in newborn pigs. Another objective was to determine whether sildenafil cau...

Prolonged hypoxia leads to the development of pulmonary hypertension. Recent reports have suggested enhancement of heme oxygenase (HO), the major source of intracellular carbon monoxide (CO), prevents hypoxia-induced pulmonary hypertension and vascular remodeling in rats. Therefore, we hypothesized that inhibition of HO activity by tin protoporphyrin (SnPP) would exacerbate the development of p...

AIM To investigate the expression of B-type natriuretic peptide-45 (BNP-45) gene which was induced by systemic chronic hypoxia, and whether these changes would be different from BNP-45 protein in the plasma and its mRNA in the ventricular myocardial. This study also aimed to test the hypothesis that systemic chronic hypoxia may cause heart failure. METHODS Although clinical use of BNP as a bi...

BACKGROUND The physiological challenges posed by hypobaric hypoxia warrant exploration of pharmacological entities to improve acclimatization to hypoxia. The present study investigates the preclinical efficacy of sphingosine-1-phosphate (S1P) to improve acclimatization to simulated hypobaric hypoxia. EXPERIMENTAL APPROACH Efficacy of intravenously administered S1P in improving haematological ...

This review describes the ways in which the primary bradycardia and peripheral vasoconstriction evoked by selective stimulation of peripheral chemoreceptors can be modified by the secondary effects of a chemoreceptor-induced increase in ventilation. The evidence that strong stimulation of peripheral chemoreceptors can evoke the behavioural and cardiovascular components of the alerting or defenc...

STAHLMAN, M.,J. GRAY, W.C. YOUNG,AND F.M. SHEPARD. Cardiovascular response of the neonatal lamb to hypoxia and hypercapnia. Am. J. Physiol. 213(4): 899-904. 1967.-The effects of hypoxia and hypercapnia on the circulatory dynamics of the unanesthetized newborn lamb were evaluated. Hypoxia produced by inhalation of 8a/, 02 caused a marked increase in pulmonary arterial pressure and pulmonary vasc...

Whole brain radiation therapy (WBRT) leads to cognitive impairment in 40-50% of brain tumor survivors following treatment. Although the etiology of cognitive deficits post-WBRT remains unclear, vascular rarefaction appears to be an important component of these impairments. In this study, we assessed the effects of WBRT on the cerebrovasculature and the effects of systemic hypoxia as a potential...

Diseases featuring abnormally low alveolar PO2 are frequently accompanied by systemic effects. The common presence of an underlying inflammatory component suggests that inflammation may contribute to the pathogenesis of the systemic effects of alveolar hypoxia. While the role of alveolar macrophages in the immune and defense functions of the lung has been long known, recent evidence indicates t...