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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Factors that influence the development of the normal pulmonary vasculature are poorly understood. Since increased local production of angiotensin II (AII) by angiotensin converting enzyme (ACE) has been implicated in the medial hypertrophy of systemic and pulmonary hypertension, we questioned whether ACE and angiotensin receptor expression may influence the muscularization of the normal pulmonary vasculature during development. The approach employed measurement of lung ACE activity, assessment of local ACE expression by immunohistochemistry, and angiotensin type 1 receptor (AT1) expression by in situ hybridization in rat lungs ranging from 15 days of intrauterine life (term = 21 d) to adulthood. The temporal and spatial pattern of ACE expression was compared with that of the endothelial marker, von Willebrand factor (vWF), and the smooth muscle cell markers, alpha smooth muscle actin and smooth muscle myosin. ACE activity was first detected in lung homogenates on day 17 of gestation (1 +/- 0.2 mU/mg) and increased progressively to term (27.7 +/- 3.2 mU/mg). However, the greatest increase in lung ACE activity to adult levels (379 +/- 25.2 mU/mg) occurred between 2 and 4 wk of postnatal life. Immunohistochemistry demonstrated vWF expression by vascular endothelium throughout the lung as early as day 15 of gestation. In contrast, ACE expression was observed in the endothelium of only hilar pulmonary arteries on day 15 of gestation, and thereafter was noted to be expressed in endothelial cells of progressively more distal arteries, such that by term, endothelial cells of all muscularized arteries expressed ACE. Alveolar capillary ACE expression was not detected until day 20 of gestation, and increased dramatically after birth. Smooth muscle actin expression in lung arteries closely paralleled the expression of endothelial ACE. AT1 receptor mRNA was first expressed in the peripheral lung on day 17 of gestation by non-epithelial undifferentiated mesenchyme. In contrast, AT1 mRNA signal was much reduced in differentiated smooth muscle. We speculate that ACE expression in the fetal lung circulation may influence the muscularization of fetal pulmonary arteries by the interaction of locally produced angiotensin II with the AT1 receptor.
Am J Respir Cell Mol Biol 1996 Jun
PMID:Developmental regulation of angiotensin converting enzyme and angiotensin type 1 receptor in the rat pulmonary circulation. 865 81

Endothelin-1 is a recently discovered peptide mainly released from endothelial cells. Hypoxia and ischemia as well as numerous factors such as angiotensin 11, thrombin and transforming growth factor beta 1 stimulate the formation of the peptide. On the other hand the synthesis of endothelin is inhibited by nitric oxide and atrial natriuretic peptide via the formation of cyclic guanosine monophosphate. Released from endothelial cells endothelin-1 mediates transient vasodilation followed by a profound and longlasting vasoconstriction. Endothelin is also a mitogen for smooth muscle proliferation. Endothelins exert their biological effects via activation of specific receptors. Two different receptors have been cloned from mammalian tissues (ET(A) and ET(B) receptors). On vascular smooth muscle cells both receptors mediate contractions. Endothelial cells only express ET(B) receptors linked to the formation of nitric oxide and/or prostacyclin formation. Increased plasma concentrations of endothelin-1 have been described in a variety of diseases such as pulmonary hypertension, arteriosclerosis, renal failure, acute coronary syndromes, heart failure, migraine and vascular diseases. Recently an increasing number of endothelin receptor antagonists have been synthetized, which have been shown to inhibit endothelin-mediated vasoconstriction. Clinical studies are now ongoing to elucidate the pathophysiologic role of endothelin and the potential benefit of the blockade of the system in different disease states.
Mol Cell Biochem
PMID:Endothelin and endothelin antagonists: potential role in cardiovascular and renal disease. 873 56

Platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) have been implicated in myointimal proliferative arteriopathy, a lesion seen in monocrotaline-induced pulmonary hypertension (MIPH). The purpose of this study was to examine the expression of PDGF and bFGF in the lungs of rats given monocrotaline and to examine the effects of amrinone on the hearts and lungs of these rats. Twenty-four 26-day-old rats were randomized to receive either monocrotaline (approximately 3.6 mg/kg/d) or no monocrotaline and concomitantly to receive either amrinone (100 mg/kg/d) or no amrinone for 21 days. Lungs were examined for immunohistochemical evidence of PDGF and bFGF, and hearts were examined for effects of pulmonary hypertension and amrinone. Immunohistochemical staining of lungs showed no evidence of PDGF except in bronchioles. bFGF staining was similar between groups (no monocrotaline 25%, monocrotaline 27%, monocrotaline and amrinone 22%), and the staining was confined to the arterial walls. Rats given monocrotaline showed significantly greater right ventricular (RV) weight (0.13 +/- 0.02 g versus 0.23 +/- 0.04 g [mean +/- SD], P < 0.001), right ventricular/left ventricular (RV/LV) weight ratio (0.29 +/- 0.06 versus 0.59 +/- 0.1, P < 0.001), and lung/body weight ratio (0.006 +/- 0.001 versus 0.01 +/- 0.003, P < 0.05) than controls. Rats given monocrotaline and amrinone were not significantly different from rats given only monocrotaline with regard to RV weight, RV/LV weight ratio, or lung/body weight ratio. We conclude that the vasculopathy seen in MIPH is not associated with the presence of PDGF or bFGF, suggesting that other growth factors may mediate this process. The course of MIPH is not altered by amrinone.
Biochem Mol Med 1996 Aug
PMID:Growth factor expression and effects of amrinone in monocrotaline-induced pulmonary hypertension in rats. 881 41

This study was designed to evaluate the effects of amlodipine, a new calcium channel blocker, on the development of right ventricular hypertrophy and thickening of the media of the pulmonary arteries in a rat model of pulmonary hypertension. Pulmonary hypertension was induced in rats by administering a single injection of monocrotaline, 80 mg/kg. The oral administration of amlodipine, 3, 10, or 30 mg/kg/day, was initiated 24 hours later (day 1). On day 28 of therapy, we determined the right ventricular systolic pressure (RVSP), the mass ratio of the right ventricle (RV) to the left ventricle, the thickness of the wall of the RV, the diameter of myocardial fibers in the RV, the percent thickness of the media of the pulmonary artery, and the percent area of smooth muscle in the pulmonary arteries. The magnitude of all parameters was significantly less in the rats administered amlodipine, 30 mg/kg/day, vs. the control group given monocrotaline alone. RVSP, the percent medial thickness, and the percent smooth muscle area, were significantly lower in rats administered a dose of amlodipine, 30 mg/kg/day vs. 10 mg/kg/day. The oral administration of amlodipine, 30 mg/kg/day, inhibited the development of RV hypertrophy and medial thickening of the pulmonary arteries in rats exposed to monocrotaline significantly more effectively vs. the untreated control exposed only to monocrotaline.
Res Commun Mol Pathol Pharmacol 1996 Jan
PMID:Amlodipine inhibits the development of right ventricular hypertrophy and medial thickening of pulmonary arteries in a rat model of pulmonary hypertension. 882 28

Nitric oxide (NO), the free radical that accounts for the biological activity of endothelium-derived relaxing factor, is synthesized from L-arginine by NO synthase (NOS). There is evidence that NO availability is reduced in the peripheral vasculature of patients with congestive heart failure (CHF). The aim of this study was to investigate the expression of NOS in the descending aorta and in the skeletal muscles of rats subjected to heart failure. The alkaloid, monocrotaline, was used to induce pulmonary hypertension and cardiac failure in rats. The expression of both the constitutive (ecNOS) and the inducible (iNOS) isoforms of the enzyme was assessed by Western blot analysis. In CHF animals, the ecNOS location in the aorta is altered: the endothelial protein expression is substantially reduced (from 0.083 +/- 0.012 to 0.003 +/- 0.004 OD/microgram total proteins, P < 0.001) whereas the expression of ecNOS in the smooth muscle is increased (from 0.024 +/- 0.004 to 0.059 +/- 0.009 OD/ microgram total proteins, P < 0.01). The total aortic ecNOS is diminished in CHF respect to control animals (0.062 +/- 0.009 v 0.107 +/- 0.013 OD/microgram total proteins, P < 0.01). On the contrary, no difference in ecNOS protein expression was observed in the extensor digitorum longus and soleus muscles. Furthermore, iNOS was not detected in any of the tissues considered. In conclusion, experimental CHF causes a re-setting of the ecNOS protein expression in the descending aorta but not in skeletal muscles. The reduced abundance of ecNOS in the aortic endothelium is consistent with the impairment of the vasodilating function reported in patients with CHF.
J Mol Cell Cardiol 1996 Nov
PMID:Aorta and skeletal muscle NO synthase expression in experimental heart failure. 893 77

Thickening of peripheral pulmonary arteries (PA) in the pulmonary hypertensive neonate has been well described morphologically, but less is known regarding the role of cell proliferation in either the normal or hypertensive neonatal PA. Thus we studied DNA synthetic indices in the tunica media and tunica adventitia of four different sizes/generations of PA in normoxic calves (n = 15) and calves exposed to hypobaric hypoxia (n = 15) during the first 14 days of life. DNA synthetic indices were determined by incorporation of the thymidine analogue bromodeoxyuridine (BrdU). Hemodynamic studies confirmed a steady decline in PA pressure in normal neonatal calves during the first 2 wk of life and progressive pulmonary hypertension in the hypoxic group. Lungs were perfusion-fixed and pulmonary arteries were evaluated for BrdU incorporation by immunohistochemistry. DNA synthetic indices (BrdU-labeled cells/1,000 cells) in the tunica media from normoxic calves were highest between 4 and 7 days postpartum and decreased to their lowest levels by day 14. The highest indices were observed in smaller generations of PA in the normoxic newborn. Adventitial cells exhibited the same general pattern of BrdU incorporation except that the postpartum peak occurred earlier, at 1 to 4 days. Exposure to hypoxia significantly increased (P = 0.001) DNA synthetic indices in both the tunica media and adventitia. The highest DNA synthetic indices were observed in smaller-generation vessels. These findings indicate that the fraction of cells traversing the S phase (i.e., actively replicating in the cell cycle) in the normal neonatal pulmonary vasculature during transition are initially high compared to reported rates in hilar PA from adult rats, but then decrease by 14 days after birth. Further, exposure to hypoxia during transition dramatically increases and prolongs pulmonary vascular cell proliferation. We conclude that structural remodeling in the hypertensive neonatal PA is due partly to increased cell proliferation in the tunica media and adventitia.
Am J Respir Cell Mol Biol 1997 Apr
PMID:Hypoxia increases bromodeoxyuridine labeling indices in bovine neonatal pulmonary arteries. 911 46

The metabolism and distribution of 14C-monocrotaline in Fisher 344 (F344) rats was compared with that in Sprague-Dawley (SD) rats. In vitro microsomal preparations, in situ isolated perfused livers and in vivo excretion and distribution studies were used to discern any differences between these two strains. These strains have previously been shown to differ in their susceptibility to monocrotaline-induced pulmonary hypertension. Hepatic phase I metabolism appears to be similar in both strains with N-oxidation and dehydrogenation to the reactive pyrroles as the major pathways. During the liver perfusions, SD rats generated more monocrotalic acid than F344 rats, but the microsome and excretion studies demonstrated no significant differences in the amount of monocrotalic acid. Monocrotalic acid is a stable byproducer of dehydromonocrotaline reacting with cellular nucleophiles and indicates the amount of monocrotaline dehydrogenation when carboxylesterase activity is negligible. These data suggest that the differences in strain susceptibility to pulmonary vascular toxicity is most likely due to differences in their response to the toxic metabolites.
Comp Biochem Physiol B Biochem Mol Biol 1997 May
PMID:Monocrotaline metabolism and distribution in Fisher 344 and Sprague-Dawley rats. 918 20

Prostaglandins have emerged as a therapeutic option for patients with peripheral vascular disease as well as pulmonary hypertension as a means to increase blood flow. We tested the hypothesis that prostaglandins regulate vascular endothelial growth factor (VEGF) expression in the human monocytic THP-1 cell line and in isolated perfused rat lungs. Our data show that the stable PGI2-analogue iloprost induces VEGF gene expression (predominantly VEGF121, but also VEGF165 isoforms) and VEGF protein synthesis in THP-1 cells. This effect is abolished by dexamethasone and by Rp-cAMP, a specific inhibitor of cAMP-dependent protein kinase (PKA) activation. The calcium channel blocker diltiazem has no effect on the iloprost-induced VEGF gene expression, and depletion of intracellular Ca2+ stores by long-term exposure (16 h) of THP-1 cells to thapsigargin does not inhibit iloprost-induced VEGF gene expression, suggesting that an increase in intracellular Ca2+ is not essential for VEGF gene induction by iloprost. However, an increase of intracellular Ca2+ by a short-term (2 h) exposure of THP-1 cells to thapsigargin or to the calcium-ionophore A23187 increases VEGF mRNA levels, indicating that a change in intracellular Ca2+ by itself can alter VEGF gene expression. The effects of thapsigargin or A23187 on VEGF gene expression are also mediated via cAMP-PKA since they are inhibited by Rp-cAMP. In isolated perfused rat lungs, PGI2 and PGE2 increases VEGF mRNA abundance whereas Rp-cAMP inhibits the prostaglandin-induced VEGF gene activation. Thus, our data suggest that prostaglandins stimulate VEGF gene expression in monocytic cells and in rat lungs via a cAMP-dependent mechanism.
Am J Respir Cell Mol Biol 1997 Dec
PMID:Prostaglandins induce vascular endothelial growth factor in a human monocytic cell line and rat lungs via cAMP. 940 62

After being dehydrogenated by cytochrome P450 enzymes in the liver, monocrotaline's highly-reactive pyrrole metabolite, dehydromonocrotaline, is believed to interact with pulmonary artery endothelial cells to initiate a pulmonary vascular toxicity resembling pulmonary hypertension. Glutathione, an abundant antioxidant in pulmonary artery endothelial cells, has been shown to react with and detoxify the pyrrolic metabolites derived from monocrotaline in the liver. Using high-performance liquid chromatography with electrochemical detection, glutathione levels were measured in a time- and dose-dependent manner in human pulmonary artery endothelial cells following treatment with dehydromonocrotaline, dehydroretronecine and N-ethylmaleimide and bovine pulmonary artery endothelial cells after treatment with dehydromonocrotaline. The bovine cells had 40% less glutathione than the human in the control groups. Bovine pulmonary artery endothelial glutathione levels were depleted 20% more than the human at 15 minutes when treated with 100 microM dehydromonocrotaline. 15 microM N-ethylmaleimide caused an 80% depletion of glutathione compared to a 30% depletion with 15 microM dehydromonocrotaline in human pulmonary artery endothelial cells.
Res Commun Mol Pathol Pharmacol 1998 Jan
PMID:Effect of monocrotaline metabolites on glutathione levels in human and bovine pulmonary artery endothelial cells. 952 55

Vascular endothelial growth factor (VEGF) is a potent mitogenic and permeability factor targeting predominantly endothelial cells. At least two tyrosine kinase receptors, Flk-1 and Flt-1, mediate its action and are mostly expressed by endothelial cells. VEGF and VEGF receptor expression are upregulated by hypoxia in vivo and the role of VEGF in hypoxia-induced angiogenesis has been extensively studied in a variety of disease entities. Although VEGF and its receptors are abundantly expressed in the lung, their role in hypoxic pulmonary hypertension and the accompanying vascular remodeling are incompletely understood. We report in this in vivo study that hypoxia increases mRNA levels for both VEGF and Flk-1 in the rat lung. The kinetics of the hypoxic response differ between receptor and ligand: Flk-1 mRNA showed a biphasic response to hypoxia with a significant, but transient, rise in mRNA levels observed after 9-15 h of hypoxic exposure and the highest levels noted after 3 wk. In contrast, VEGF mRNA levels did not show a significant increase with acute hypoxia, but increased progressively after 1-3 wk of hypoxia. By in situ hybridization, VEGF mRNA was localized predominantly in alveolar epithelial cells with increased signal in the lungs of hypoxic animals compared with controls. Immunohistochemical staining with anti-VEGF antibodies localized VEGF peptide throughout the lung parenchyma and was increased in hypoxic compared with normoxic animals. Furthermore, hypoxic animals had significantly higher circulating VEGF concentrations compared with normoxic controls. Lung vascular permeability as measured by extravasation of Evans Blue dye was not significantly different between normoxic and hypoxic animals, although a tendency for increased permeability was seen in the hypoxic animals. These findings suggest a possible role for VEGF in the pulmonary response to hypoxia.
Am J Respir Cell Mol Biol 1998 Jun
PMID:Increased vascular endothelial growth factor production in the lungs of rats with hypoxia-induced pulmonary hypertension. 961 81


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