oxalylglycine and Hypertension--Pulmonary

Pulmonary arterial hypertension (PAH) is an often fatal disease with limited treatment options. Whereas current data support the notion that, in pulmonary artery endothelial cells (PAECs), expression of transcription factor hypoxia inducible factor-1α (HIF-1α) is increased, the role of HIF-1α in pulmonary artery smooth muscle cells (PASMCs) remains controversial. This study investigates the hypothesis that, in PASMCs from patients with PAH, decreases in HIF-1α expression and activity underlie augmented pulmonary vascular contractility. PASMCs and tissues were isolated from nonhypertensive control patients and patients with PAH. Compared with controls, HIF-1α and Kv1.5 protein expression were decreased in PAH smooth muscle cells (primary culture). Myosin light chain (MLC) phosphorylation and MLC kinase (MLCK) activity-major determinants of vascular tone-were increased in patients with PAH. Cofactors involved in prolyl hydroxylase domain activity were increased in PAH smooth muscle cells. Functionally, PASMC contractility was inversely correlated with HIF-1α activity. In PASMCs derived from patients with PAH, HIF-1α expression is decreased, and MLCK activity, MLC phosphorylation, and cell contraction are increased. We conclude that compromised PASMC HIF-1α expression may contribute to the increased tone that characterizes pulmonary hypertension.-Barnes, E. A., Chen, C.-H., Sedan, O., Cornfield, D. N. Loss of smooth muscle cell hypoxia inducible factor-1α underlies increased vascular contractility in pulmonary hypertension.

Topics: Amino Acids, Dicarboxylic; Dimethyl Sulfoxide; Gene Expression Regulation; Humans; Hypertension, Pulmonary; Hypoxia-Inducible Factor 1, alpha Subunit; Myocytes, Smooth Muscle; Prolyl Hydroxylases; Pulmonary Artery; Vasoconstriction

The revascularization therapy of pulmonary embolism is associated with ischemia-reperfusion (IR) injury. However, the effect of IR injury on pulmonary arterial endothelial function has not been elucidated. Male Sprague-Dawley rats were divided into a control, an IR and an IR plus hypoxia-inducible factor 1 alpha (HIF-1α) stabilizer DMOG group. We found that the acetylcholine (ACh)-induced relaxation was dramatically reduced in pulmonary arteries from IR-injured rats compared with controls (P < 0.01). Interestingly, pre-treatment with the DMOG significantly improved ACh-stimulated pulmonary arterial dilatation (P < 0.01). The protein expression of HIF-1α in pulmonary artery was significantly down-regulated by IR injury (P < 0.01). Moreover, DMOG remarkably reversed IR-induced down-regulation of HIF-1α (P < 0.01). There was no difference in ACh-stimulated relaxation of endothelium-denuded or L-NMMA-treated pulmonary arteries among the three groups. The bioavailability of nitric oxide (NO) and the phosphorylation level of inducible NO synthase (iNOS) in pulmonary artery were significantly decreased by IR injury (both P < 0.01), which were reversed by DMOG (P < 0.05 or P < 0.01). In addition, the levels of superoxide in pulmonary artery were not affected by the IR injury as well as IR injury plus administration with DMOG. The present study demonstrated that HIF-1α contributes to pulmonary vascular dysfunction in lung IR injury.

Topics: Amino Acids, Dicarboxylic; Animals; Blotting, Western; Disease Models, Animal; Endothelium, Vascular; Hypertension, Pulmonary; Hypoxia-Inducible Factor 1, alpha Subunit; Male; Pulmonary Artery; Pulmonary Embolism; Rats; Rats, Sprague-Dawley; Reperfusion Injury

Previous work showed that dehydroepiandrosterone (DHEA) prevents and reverses chronic hypoxic pulmonary artery hypertension in rat via targeting smooth muscle cells. In our study, DHEA was tested on human pulmonary arterial smooth muscle cells (HPASMC) to identify its mechanism of action under hypoxia in vitro. We show that DHEA decreased HIF-1alpha accumulation under both "chemical hypoxia" with treatment by the iron chelator deferroxamin and gas hypoxia (1% O2). The mRNA levels of HIF-1alpha were unchanged whether or not DHEA was applied under chemical and gas hypoxia, as compared to controls in normoxia, suggesting a post-transcriptional effect of the steroid. Protein levels of prolyl hydroxylases responsible for HIF-1alpha degradation were not modified by DHEA treatment. In addition, a synthetic derivative of DHEA, 3beta-methyl-Delta5-androsten-17-one (which cannot be metabolized), was as active as DHEA on HIF-1alpha accumulation, as well as testosterone and 17beta-estradiol (E2). In HPASMC cultures under normoxia and both types of hypoxia, DHEA gave rise to Delta5-androstene-3beta,17beta-diol (ADIOL) and DHEA-sulfate (DHEA-S). Neither testosterone, nor E2 were found. In addition, ADIOL, DHEA-S, 7alpha-hydroxy-DHEA and Delta4-androstene-3,17-dione were ineffective on HIF-1alpha accumulation. The effect of DHEA per se reducing HIF-1alpha accumulation may be relevant to reduced hypoxia effects in pulmonary arterial hypertension.

Topics: Amino Acids, Dicarboxylic; Base Sequence; Cells, Cultured; Cobalt; Deferoxamine; Dehydroepiandrosterone; DNA Primers; Enzyme Inhibitors; Estradiol; Humans; Hypertension, Pulmonary; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Iron Chelating Agents; Models, Cardiovascular; Myocytes, Smooth Muscle; Procollagen-Proline Dioxygenase; Pulmonary Artery; Testosterone