1
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Chen T, Zhou Q, Tang H, Bozkanat M, Yuan JXJ, Raj JU, Zhou G. miR-17/20 Controls Prolyl Hydroxylase 2 (PHD2)/Hypoxia-Inducible Factor 1 (HIF1) to Regulate Pulmonary Artery Smooth Muscle Cell Proliferation. J Am Heart Assoc 2016; 5:JAHA.116.004510. [PMID: 27919930 PMCID: PMC5210422 DOI: 10.1161/jaha.116.004510] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background Previously we found that smooth muscle cell (SMC)‐specific knockout of miR‐17~92 attenuates hypoxia‐induced pulmonary hypertension. However, the mechanism underlying miR‐17~92‐mediated pulmonary artery SMC (PASMC) proliferation remains unclear. We sought to investigate whether miR‐17~92 regulates hypoxia‐inducible factor (HIF) activity and PASMC proliferation via prolyl hydroxylases (PHDs). Methods and Results We show that hypoxic sm‐17~92−/− mice have decreased hematocrit, red blood cell counts, and hemoglobin contents. The sm‐17~92−/− mouse lungs express decreased mRNA levels of HIF targets and increased levels of PHD2. miR‐17~92 inhibitors suppress hypoxia‐induced levels of HIF1α, VEGF, Glut1, HK2, and PDK1 but not HIF2α in vitro in PASMC. Overexpression of miR‐17 in PASMC represses PHD2 expression, whereas miR‐17/20a inhibitors induce PHD2 expression. The 3′‐UTR of PHD2 contains a functional miR‐17/20a seed sequence. Silencing of PHD2 induces HIF1α and PCNA protein levels, whereas overexpression of PHD2 decreases HIF1α and cell proliferation. SMC‐specific knockout of PHD2 enhances hypoxia‐induced vascular remodeling and exacerbates established pulmonary hypertension in mice. PHD2 activator R59949 reverses vessel remodeling in existing hypertensive mice. PHDs are dysregulated in PASMC isolated from pulmonary arterial hypertension patients. Conclusions Our results suggest that PHD2 is a direct target of miR‐17/20a and that miR‐17~92 contributes to PASMC proliferation and polycythemia by suppression of PHD2 and induction of HIF1α.
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Affiliation(s)
- Tianji Chen
- Department of Pediatrics, University of Illinois at Chicago, Chicago, IL
| | - Qiyuan Zhou
- Department of Pediatrics, University of Illinois at Chicago, Chicago, IL
| | - Haiyang Tang
- Department of Medicine, University of Arizona, Tucson, AZ
| | - Melike Bozkanat
- Department of Pediatrics, University of Illinois at Chicago, Chicago, IL
| | - Jason X-J Yuan
- Department of Medicine, University of Arizona, Tucson, AZ
| | - J Usha Raj
- Department of Pediatrics, University of Illinois at Chicago, Chicago, IL.,Children's Hospital University of Illinois, University of Illinois Hospital and Health Sciences System, Chicago, IL
| | - Guofei Zhou
- Department of Pediatrics, University of Illinois at Chicago, Chicago, IL
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2
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Abstract
Vascular homeostasis is regulated by complex interactions between many vascular cell components, including endothelial cells, vascular smooth muscle cells (VSMCs), adventitial inflammatory cells, and autonomic nervous system. The balance between oxidant and antioxidant systems determines intracellular redox status, and their imbalance can cause oxidative stress. Excessive oxidative stress is one of the important stimuli that induce cellular damage and dysregulation of vascular cell components, leading to vascular diseases through multiple pathways. Cyclophilin A (CyPA) is one of the causative proteins that mediate oxidative stress-induced cardiovascular dysfunction. CyPA was initially discovered as the intracellular receptor of the immunosuppressive drug cyclosporine 30 years ago. However, recent studies have established that CyPA is secreted from vascular cell components, such as endothelial cells and VSMCs. Extracellular CyPA augments the development of cardiovascular diseases. CyPA secretion is regulated by Rho-kinase, which contributes to the pathogenesis of vasospasm, arteriosclerosis, ischemia/reperfusion injury, hypertension, pulmonary hypertension, and heart failure. We recently reported that plasma CyPA levels are significantly higher in patients with coronary artery disease, which is associated with increased numbers of stenotic coronary arteries and the need for coronary intervention in such patients. Furthermore, we showed that the vascular erythropoietin (Epo)/Epo receptor system plays an important role in production of nitric oxide and maintenance of vascular redox state and homeostasis, with a potential mechanistic link to the Rho-kinase-CyPA pathway. In this article, I review the data on the protective role of the vascular Epo/Epo receptor system and discuss the roles of the CyPA/Rho-kinase system in cardiovascular diseases.
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Affiliation(s)
- Kimio Satoh
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine
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3
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Samillan V, Haider T, Vogel J, Leuenberger C, Brock M, Schwarzwald C, Gassmann M, Ostergaard L. Combination of erythropoietin and sildenafil can effectively attenuate hypoxia-induced pulmonary hypertension in mice. Pulm Circ 2014; 3:898-907. [PMID: 25006406 DOI: 10.1086/674758] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 08/22/2013] [Indexed: 12/12/2022] Open
Abstract
Pulmonary hypertension (PH) is an incurable disease that often leads to right ventricular hypertrophy and right heart failure. This study investigated single versus combined therapy with sildenafil and erythropoietin on hypoxia-induced pulmonary hypertension in mice. Mice were randomized into 5 groups and exposed to either hypoxia (10% oxygen) or normoxia for a total of 5 weeks. Hypoxic mice were treated with saline solution, erythropoietin (500 IU/kg 3 times weekly), sildenafil (10 mg/kg daily), or a combination of the two drugs for the last 2 weeks of hypoxic exposure. We measured right ventricular pressures using right heart catheterization, and the ventilatory response to hypoxia was recorded via whole-body plethysmography. Histological analyses were performed to elucidate changes in pulmonary morphology and appearance of right heart hypertrophy. Plasma levels of cardiotrophin-1 and atrial natriuretic peptide were quantified. Treatment with either erythropoietin or sildenafil alone lowered the hypoxia-induced increase of pulmonary pressure and reduced pulmonary edema formation, pulmonary vascular remodeling, and right ventricular hypertrophy. Notably, the combination of the two drugs had the most prominent effect. Changes in cardiotrophin-1 and atrial natriuretic protein levels confirmed these observations. The combination treatment with erythropoietin and sildenafil demonstrated an attenuation of the development of hypoxia-induced PH in mice that was superior to that observed for either drug when given alone.
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Affiliation(s)
- Victor Samillan
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland ; Human Physiology Department, Medical School, Universidad Alas Peruanas, Lima, Peru
| | - Thomas Haider
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland
| | - Johannes Vogel
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland
| | - Caroline Leuenberger
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Institute of Human Movement Sciences and Sport, ETH Zurich, Zurich, Switzerland
| | - Matthias Brock
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Division of Pulmonology, University Hospital Zurich, Zurich, Switzerland
| | - Colin Schwarzwald
- Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Max Gassmann
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland ; Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Louise Ostergaard
- Institute for Veterinary Physiology, Vetsuisse Faculty, Zurich, Switzerland ; Zurich Center for Integrative Human Physiology, Zurich, Switzerland
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4
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Kuriyama S, Morio Y, Toba M, Nagaoka T, Takahashi F, Iwakami SI, Seyama K, Takahashi K. Genistein attenuates hypoxic pulmonary hypertension via enhanced nitric oxide signaling and the erythropoietin system. Am J Physiol Lung Cell Mol Physiol 2014; 306:L996-L1005. [PMID: 24705719 DOI: 10.1152/ajplung.00276.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Upregulation of the erythropoietin (EPO)/EPO receptor (EPOR) system plays a protective role against chronic hypoxia-induced pulmonary hypertension (hypoxic PH) through enhancement of endothelial nitric oxide (NO)-mediated signaling. Genistein (Gen), a phytoestrogen, is considered to ameliorate NO-mediated signaling. We hypothesized that Gen attenuates and prevents hypoxic PH. In vivo, Sprague-Dawley rats raised in a hypobaric chamber were treated with Gen (60 mkg/kg) for 21 days. Pulmonary hemodynamics and vascular remodeling were ameliorated in Gen-treated hypoxic PH rats. Gen also restored cGMP levels and phosphorylated endothelial NO synthase (p-eNOS) at Ser(1177) and p-Akt at Ser(473) expression in the lungs. Additionally, Gen potentiated plasma EPO concentration and EPOR-positive endothelial cell counts. In experiments with hypoxic PH rats' isolated perfused lungs, Gen caused NO- and phosphatidylinositol 3-kinase (PI3K)/Akt-dependent vasodilation that reversed abnormal vasoconstriction. In vitro, a combination of EPO and Gen increased the p-eNOS and the EPOR expression in human umbilical vein endothelial cells under a hypoxic environment. Moreover, Gen potentiated the hypoxic increase in EPO production from human hepatoma cells. We conclude that Gen may be effective for the prevention of hypoxic PH through the improvement of PI3K/Akt-dependent, NO-mediated signaling in association with enhancement of the EPO/EPOR system.
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Affiliation(s)
- Sachiko Kuriyama
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yoshiteru Morio
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Michie Toba
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tetsutaro Nagaoka
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Fumiyuki Takahashi
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Shin-Ichiro Iwakami
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Kuniaki Seyama
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Kazuhisa Takahashi
- Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
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5
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Kosmadakis G, Aguilera D, Carceles O, Da Costa Correia E, Boletis I. Pulmonary Hypertension in Dialysis Patients. Ren Fail 2013; 35:514-20. [DOI: 10.3109/0886022x.2013.766559] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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6
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Emergence of the erythropoietin/erythropoietin receptor system as a novel cardiovascular therapeutic target. J Cardiovasc Pharmacol 2012; 58:570-4. [PMID: 21934628 DOI: 10.1097/fjc.0b013e318235e7bb] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Although hypoxia and ischemia are known to be involved in the pathogenesis of cardiovascular disease, specific therapeutic targets still remain elusive. To address this important issue, we have performed 2 series of experimental studies, aiming at erythropoietin (Epo)/Epo receptor (EpoR) based on the following backgrounds. Epo has long been regarded as a hematopoietic hormone that acts exclusively in the proliferation and differentiation of erythroid progenitors. Although recent studies have demonstrated that EpoR is expressed in the cardiovascular system, the potential protective role of the vascular Epo/EpoR system in vivo remains to be examined. We hypothesized that the vascular Epo/EpoR system plays an important protective role against the development of cardiovascular disease. Using vascular EpoR-deficient mouse, we demonstrated that the vascular Epo/EpoR system plays a crucial role for endothelial function and vascular homeostasis. The vascular Epo/EpoR system is important for the activation of the vascular endothelial growth factor/vascular endothelial growth factor receptor-2 system, inhibits hypoxia-induced pulmonary endothelial damage and promotes ischemia-induced angiogenesis in vivo. These results indicate that the vascular Epo/EpoR system plays an important protective role against hypoxia/ischemia, demonstrating that this system is a novel therapeutic target in cardiovascular medicine.
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7
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Ünal A, Sipahioglu M, Oguz F, Kaya M, Kucuk H, Tokgoz B, Buyukoglan H, Oymak O, Utas C. Pulmonary Hypertension in Peritoneal Dialysis Patients: Prevalence and Risk Factors. Perit Dial Int 2008. [DOI: 10.1177/089686080902900214] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Aim To investigate the prevalence of pulmonary arterial hypertension (PAH) and the possible contributing factors for PAH in patients receiving regular continuous ambulatory peritoneal dialysis (CAPD). Patients and Methods The study included 135 CAPD patients and 15 disease-free controls. Patients that had chronic obstructive pulmonary disease, severe mitral or aortic valve disease, connective tissue disease, history of pulmonary embolism, left ventricular ejection fraction <50%, or chest wall or parenchymal lung disease were excluded. All patients and controls were examined using echocardiography and bioelectrical impedance analysis. PAH was defined as systolic pulmonary artery pressure (PAP) >35 mmHg at rest. Results Mean systolic PAP was higher in the CAPD patients than in the controls (19.66 ± 11.66 vs 14.27 ± 4.55 mmHg, p = 0.001). PAH was detected in 17 (12.6%) of the 135 CAPD patients. Mean systolic PAP was significantly higher in patients with PAH than in those without PAH (42.00 ± 9.13 vs 16.44 ± 7.83 mmHg, p = 0.001). Serum albumin level and ejection fraction were lower in patients with PAH than in those without PAH ( p = 0.001 and 0.003 respectively). The ratio of extracellular water/total body water (ECW/TBW), which can reflect hydration status, was significantly higher in patients with PAH than in those without PAH ( p = 0.008). In the PD group, no patients were hypovolemic; 51 (37.8%) of the 135 PD patients were hypervolemic and 84 (62.2%) were normovolemic. Only 3 of the 17 patients with PAH were normovolemic; the rest were hypervolemic. Mean systolic PAP was significantly higher in hypervolemic PD patients (24.57 ± 14.19 mmHg) than in normovolemic PD patients (16.68 ± 7.61 mmHg) ( p = 0.001). PAP correlated with ECW/TBW ( r=0.317, p = 0.001) and left ventricular mass index (LVMI; r=0.286, p = 0.001). On the other hand, it inversely correlated with serum albumin level ( r = –0.281, p = 0.001), hemoglobin level ( r = –0.165, p = 0.044), and ejection fraction ( r = –0.263, p = 0.001). Serum albumin level, ECW/TBW, and LVMI were found in multivariate analysis to be independent risk factors for PAP. Conclusion PAH is a frequent cardiovascular complication in CAPD patients. Serum albumin level, hypervolemia, and LVMI are major risk factors for PAH. Therefore, strategies for treatment of hypervolemia, left ventricular hypertrophy, and hypoalbuminemia should be enhanced to prevent the development of PAH in CAPD patients.
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Affiliation(s)
- Aydin Ünal
- Departments of Nephrology, Erciyes University, Kayseri, Turkey
| | | | - Fatih Oguz
- Cardiology, Erciyes University, Kayseri, Turkey
| | - Mehmet Kaya
- Cardiology, Erciyes University, Kayseri, Turkey
| | - Hamit Kucuk
- Internal Medicine, Erciyes University, Kayseri, Turkey
| | - Bulent Tokgoz
- Departments of Nephrology, Erciyes University, Kayseri, Turkey
| | | | - Oktay Oymak
- Departments of Nephrology, Erciyes University, Kayseri, Turkey
| | - Cengiz Utas
- Departments of Nephrology, Erciyes University, Kayseri, Turkey
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8
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Ali O, Wharton J, Gibbs JSR, Howard L, Wilkins MR. Emerging therapies for pulmonary arterial hypertension. Expert Opin Investig Drugs 2007; 16:803-18. [PMID: 17501693 DOI: 10.1517/13543784.16.6.803] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pulmonary arterial hypertension is characterised by increased pulmonary vascular resistance due to increased vascular tone and structural remodelling of pulmonary vessels. The therapies that are in use so far have been developed to correct endothelial dysfunction and reduce vasomotor tone. These treatments have a limited effect on the remodelling process and, increasingly, the focus is turning to potent strategies for inhibiting vascular proliferation and promoting vascular apoptosis. Multiple novel targets have been uncovered over the last 5 years and several are now in early clinical trials. At present, it is clear that there is no single treatment for the condition. Although this is the case, studies are investigating the role of combining therapies that are already established.
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Affiliation(s)
- Omar Ali
- Imperial College London, Experimental Medicine & Toxicology, Hammersmith Hospital, London, UK
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9
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Buemi M, Senatore M, Gallo G, Crascì E, Campo S, Sturiale A, Coppolino G, Bolignano D, Frisina N. Pulmonary Hypertension and Erythropoietin. Kidney Blood Press Res 2007; 30:248-52. [DOI: 10.1159/000104443] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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10
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Satoh K, Kagaya Y, Nakano M, Ito Y, Ohta J, Tada H, Karibe A, Minegishi N, Suzuki N, Yamamoto M, Ono M, Watanabe J, Shirato K, Ishii N, Sugamura K, Shimokawa H. Important role of endogenous erythropoietin system in recruitment of endothelial progenitor cells in hypoxia-induced pulmonary hypertension in mice. Circulation 2006; 113:1442-50. [PMID: 16534010 DOI: 10.1161/circulationaha.105.583732] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Recent studies have suggested that endogenous erythropoietin (Epo) plays an important role in the mobilization of bone marrow-derived endothelial progenitor cells (EPCs). However, it remains to be elucidated whether the Epo system exerts protective effects on pulmonary hypertension (PH), a fatal disorder encountered in cardiovascular medicine. METHODS AND RESULTS A mouse model of hypoxia-induced PH was used for study. We evaluated right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling in mice lacking the Epo receptor (EpoR) in nonerythroid lineages (EpoR(-/-) rescued mice) after 3 weeks of exposure to hypoxia. Those mice lack EpoR in the cardiovascular system but not in the hematopoietic system. The development of PH and pulmonary vascular remodeling were accelerated in EpoR(-/-) rescued mice compared with wild-type mice. The mobilization of EPCs and their recruitment to the pulmonary endothelium were significantly impaired in EpoR(-/-) rescued mice. By contrast, reconstitution of the bone marrow with wild-type bone marrow cells ameliorated PH in the EpoR(-/-) rescued mice. Hypoxia enhanced the expression of EpoR on pulmonary endothelial cells in wild-type but not EpoR(-/-) rescued mice. Finally, hypoxia activated endothelial nitric oxide synthase in the lungs in wild-type mice but not in EpoR(-/-) rescued mice. CONCLUSIONS These results indicate that the endogenous Epo/EpoR system plays an important role in the recruitment of EPCs and prevents the development of PH during chronic hypoxia in mice in vivo, suggesting the therapeutic importance of the system for the treatment of PH.
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MESH Headings
- Animals
- Bone Marrow Transplantation
- Cell Movement
- Cells, Cultured/cytology
- Chronic Disease
- Endothelial Cells/pathology
- Endothelium/pathology
- Endothelium, Vascular/pathology
- Enzyme Activation
- Erythroid Precursor Cells/metabolism
- Erythropoietin/physiology
- GATA1 Transcription Factor/physiology
- Heart Failure/etiology
- Hematopoietic Stem Cells/physiology
- Hypertension, Pulmonary/etiology
- Hypertension, Pulmonary/prevention & control
- Hypertrophy, Right Ventricular/etiology
- Hypertrophy, Right Ventricular/physiopathology
- Hypoxia/complications
- Hypoxia/physiopathology
- Lung/blood supply
- Lung/pathology
- Male
- Mice
- Mice, Knockout
- Mice, Transgenic
- Muscle, Smooth, Vascular/pathology
- Nitric Oxide Synthase Type III/metabolism
- Organ Specificity
- Radiation Chimera
- Receptor, TIE-2/genetics
- Receptors, Erythropoietin/deficiency
- Receptors, Erythropoietin/genetics
- Receptors, Erythropoietin/physiology
- Systole
- Ventricular Dysfunction, Right/etiology
- Ventricular Dysfunction, Right/physiopathology
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Affiliation(s)
- Kimio Satoh
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
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11
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Littler CM, Wehling CA, Wick MJ, Fagan KA, Cool CD, Messing RO, Dempsey EC. Divergent contractile and structural responses of the murine PKC-epsilon null pulmonary circulation to chronic hypoxia. Am J Physiol Lung Cell Mol Physiol 2005; 289:L1083-93. [PMID: 16085670 DOI: 10.1152/ajplung.00472.2004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Loss of PKC-epsilon limits the magnitude of acute hypoxic pulmonary vasoconstriction (HPV) in the mouse. Therefore, we hypothesized that loss of PKC-epsilon would decrease the contractile and/or structural response of the murine pulmonary circulation to chronic hypoxia (Hx). However, the pattern of lung vascular responses to chronic Hx may or may not be predicted by the acute HPV response. Adult PKC-epsilon wild-type (PKC-epsilon(+/+)), heterozygous null, and homozygous null (PKC-epsilon(-/-)) mice were exposed to normoxia or Hx for 5 wk. PKC-epsilon(-/-) mice actually had a greater increase in right ventricular (RV) systolic pressure, RV mass, and hematocrit in response to chronic Hx than PKC-epsilon(+/+) mice. In contrast to the augmented PA pressure and RV hypertrophy, pulmonary vascular remodeling was increased less than expected (i.e., equal to PKC-epsilon(+/+) mice) in both the proximal and distal PKC-epsilon(-/-) pulmonary vasculature. The contribution of increased vascular tone to this pulmonary hypertension (PHTN) was assessed by measuring the acute vasodilator response to nitric oxide (NO). Acute inhalation of NO reversed the increased PA pressure in hypoxic PKC-epsilon(-/-) mice, implying that the exaggerated PHTN may be due to a relative deficiency in nitric oxide synthase (NOS). Despite the higher PA pressure, chronic Hx stimulated less of an increase in lung endothelial (e) and inducible (i) NOS expression in PKC-epsilon(-/-) than PKC-epsilon(+/+) mice. In contrast, expression of nNOS in PKC-epsilon(+/+) mice decreased in response to chronic Hx, while lung levels in PKC-epsilon(-/-) mice remained unchanged. In summary, loss of PKC-epsilon results in increased vascular tone, but not pulmonary vascular remodeling in response to chronic Hx. Blunting of Hx-induced eNOS and iNOS expression may contribute to the increased vascular tone. PKC-epsilon appears to be an important signaling intermediate in the hypoxic regulation of each NOS isoform.
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Affiliation(s)
- C M Littler
- Cardiovascular Pulmonary Research Laboratory, B-133, University of Colorado Health Sciences Center, 4200 E. 9th Avenue, Denver, CO 80262, USA.
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12
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Sakai A, Matsumoto T, Saitoh M, Matsuzaki T, Koizumi T, Ishizaki T, Ruan ZH, Wang ZG, Chen QH, Wang XQ. Cardiopulmonary Hemodynamics of Blue-Sheep, Pseudois nayaur, as High-Altitude Adapted Mammals. ACTA ACUST UNITED AC 2003; 53:377-84. [PMID: 14975184 DOI: 10.2170/jjphysiol.53.377] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The blue-sheep, pika, and yak live in the Tibetan highlands at an altitude of 6,100 m and are typical mammals adapted to high-altitudes. These animals have a long history of habitation at high-altitudes and are considered to be "animals completely adapted to high-altitudes" because of their physiological and morphological traits that are well adapted to high-altitude environments. To evaluate the physiological characteristics of high-altitude adaptation in the blue-sheep, changes in the pulmonary hemodynamics during exposure to simulated-altitudes at 0, 2,300, and 4,500 m were examined by means of a climatic chamber in Qinghai Province, China (altitude 2,300 m). Seven blue-sheep inhabiting the mountains (3,000 m) of Qinghai Province, China, were compared with 5 pigs raised in the same area as controls. The primary items of measurement were the body weight (BW), systemic arterial pressure (Psa), pulmonary artery pressure (Ppa), hematocrit (Ht), left ventricular weight (LVW), right ventricular weight (RVW), and blood gas profile. The principal findings of this study are: (1) Ht, an index of right ventricular hypertrophy (RVW/LVW), and oxygen consumption (Vdot;O(2)) were significantly lower in the blue sheep compared with the pigs; (2) When the animals were exposed to simulated-altitudes at 0, 2,300, and 4,500 m, Ppa increased significantly in tandem with altitude elevation in both species, but the increases were significantly smaller in the blue-sheep; and (3) Ppa/Psa, an index of the right ventricular load, increased with the altitude in both species, but the increases were smaller in the blue sheep. From these observations, low Ht and RVW/LVW and significant attenuation of hypoxic pulmonary vasoconstriction (HPV) in the blue-sheep is considered to be characteristics of animals completely adapted to high-altitudes, such as the pika.
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Affiliation(s)
- Akio Sakai
- Department of Sports Medicine, Shinshu University School of Medicine, Matsumoto, 390-8621 Japan.
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13
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Wagner KF, Katschinski DM, Hasegawa J, Schumacher D, Meller B, Gembruch U, Schramm U, Jelkmann W, Gassmann M, Fandrey J. Chronic inborn erythrocytosis leads to cardiac dysfunction and premature death in mice overexpressing erythropoietin. Blood 2001; 97:536-42. [PMID: 11154234 DOI: 10.1182/blood.v97.2.536] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The most common cause of an increase of the hematocrit is secondary to elevated erythropoietin levels. Erythrocytosis is assumed to cause higher blood viscosity that could put the cardiovascular system at hemodynamic and rheological risks. Secondary erythrocytosis results from tissue hypoxia, and one can hardly define what cardiovascular consequences are caused by chronic erythrocytosis or hypoxia. Herein, a novel transgenic (tg) mouse line is characterized that is erythrocytotic because of chronic overexpression of the human erythropoietin gene. These mice grow up well, reaching a hematocrit of about 0.80 in adulthood. Blood volume of adult tg mice was markedly increased by 75%. Unexpectedly, blood pressure was not elevated and cardiac output was not decreased. Still, the adult tg mice showed features of cardiac dysfunction with increased heart weight. In vivo, high-frequency echocardiography revealed marked ventricular dilatation that was confirmed by histologic examination. Furthermore, by transmission electron microscopy, a prominent intracellular edema of the cardiomyocytes was seen. Exercise performance of the tg mice was dramatically reduced, unmasking the severity of their compromised cardiovascular function. In addition, life expectancy of the tg mice was significantly reduced to 7.4 months. Our findings suggest that severe erythrocytosis per se results in cardiac dysfunction and markedly reduced life span.
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Affiliation(s)
- K F Wagner
- Department of Anesthesiology, the Institute of Physiology, University of Lübeck, Lübeck, Germany
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14
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Abstract
Polycythemia causes increased vascular production of nitric oxide (NO), most likely secondary to an effect of elevated vascular shear stress to enhance expression of endothelial nitric oxide synthase (eNOS). Because both polycythemia and increased eNOS expression are associated with chronic hypoxia-induced pulmonary hypertension, experiments were performed to test the hypothesis that increased hematocrit leads to upregulation of pulmonary eNOS and enhanced vascular production of NO independent of hypoxia. Rats were administered human recombinant erythropoietin (rEpo; 48 U/day) or vehicle for 2 wk. At the time of study, hematocrit was significantly greater in the rEpo-treated group than in the vehicle group (65.8 +/- 0.7% vs. 45.1 +/- 0.5%), although mean pulmonary artery pressure did not differ between treatments. Experiments on isolated, saline-perfused lungs demonstrated similar vasodilatory responses to the endothelium-derived NO-dependent agonist ionomycin in each group. Additional experiments showed that the vasoconstrictor response to the thromboxane mimetic U-46619 was diminished at lower doses in lungs from the rEpo group compared with the vehicle group. However, perfusate nitrite/nitrate concentration after 90 min of perfusion in isolated lungs was not different between groups. Additionally, no difference was detected between groups in lung eNOS levels by Western blot. We conclude that the predicted increase in shear stress associated with polycythemia does not result in altered pulmonary eNOS expression.
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Affiliation(s)
- B R Walker
- Vascular Physiology Group, Departments of Cell Biology and Physiology and Pediatrics, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA.
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15
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Hanson WL, Boggs DF, Kay JM, Hofmeister SE, Okada O, Wagner WW. Pulmonary vascular response of the coati to chronic hypoxia. J Appl Physiol (1985) 2000; 88:981-6. [PMID: 10710394 DOI: 10.1152/jappl.2000.88.3.981] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The unusually muscular pulmonary arteries normally present in cattle and swine residing at low altitude are associated with a rapid development of severe pulmonary hypertension when those animals are moved to high altitude. Because these species lack collateral ventilation, they appear to have an increased dependence on hypoxic vasoconstriction to maintain normal ventilation-perfusion balance, which, in turn, maintains thickened arterial walls. The only other species known to lack collateral ventilation is the coati, which, similarly, has thick-walled pulmonary arteries. We tested the hypothesis that coatis will develop severe high-altitude pulmonary hypertension by exposing six of these animals (Nasua narica) to a simulated altitude of 4,900 m for 6 wk. After the exposure, pulmonary arterial pressures were hardly elevated, right ventricular hypertrophy was minimal, there was no muscularization of pulmonary arterioles, and, most surprising of all, there was a decrease in medial thickness of muscular pulmonary arteries. These unexpected results break a consistent cross-species pattern in which animals with thick muscular pulmonary arteries at low altitude develop severe pulmonary hypertension at high altitude.
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Affiliation(s)
- W L Hanson
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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16
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Chen LW, Chen CF, Lai YL. Chronic activation of neurokinin-1 receptor induces pulmonary hypertension in rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H1543-51. [PMID: 10330237 DOI: 10.1152/ajpheart.1999.276.5.h1543] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study we explored the hypothesis that chronic activation of neurokinin-1 (NK-1) receptor induces pulmonary hypertension in Wistar rats. First, the activation of NK-1 receptor on the pulmonary circulation was investigated by use of a chronic injection of NK-1 agonist [Ser9,Met(O2)11]-substance P (1 x 10(-9) mol/kg) for 2 wk at sea level (rats breathed room air) and during hypoxia (rats were placed in a hypobaric 380-Torr chamber). Second, we studied the effect of NK-1 antagonist (CP-96345) on developing and developed (after 4 wk of chronic hypoxia) pulmonary hypertension. Pulmonary arterial pressure, the weight ratio of right ventricle to left ventricle + septum, hematocrit, and substance P (SP) were measured. We found that NK-1 agonist significantly increased pulmonary arterial pressure in the sea-level but not in the hypoxic group. However, NK-1 agonist induced neither right heart hypertrophy nor polycythemia. CP-96345 significantly decreased pulmonary arterial pressure in the hypoxic group but had no effect in the sea-level group. Furthermore, CP-96345 significantly attenuated the acute SP-induced increase in pulmonary arterial pressure in the sea-level and hypoxic groups, with a larger increase in the hypoxic group. These results suggest that chronic activation of NK-1 receptor induces pulmonary hypertension and that there is an increase in the sensitivity of pulmonary vessels in response to SP in chronically hypoxic rats.
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Affiliation(s)
- L W Chen
- Department of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan, Republic of China
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17
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Lai YL, Chen CF, Chien CT, Shiao HL, Thacker AA, Zhang HQ. Capsaicin pretreatment attenuates chronic hypoxic pulmonary hypertension. RESPIRATION PHYSIOLOGY 1995; 99:283-9. [PMID: 7539934 DOI: 10.1016/0034-5687(94)00098-k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Capsaicin pretreatment was used to deplete tachykinins in order to study the role of tachykinins in chronic hypoxia-induced pulmonary hypertension. Forty three young Wistar rats weighing 235 +/- 4 g were randomly divided into four groups: control (n = 10); capsaicin pretreatment (n = 10); intermittent chronic hypoxia (n = 10); and capsaicin pretreatment + intermittent chronic hypoxia (n = 13). Control animals breathed room air. Rats in the capsaicin pretreatment groups were given capsaicin via subcutaneous injection over a three-day period. Hypobaric hypoxia was intermittently applied by placing animals into a hypobaric chamber with a barometric pressure of 380 Torr for two weeks. In the capsaicin pretreatment + intermittent chronic hypoxia group, rats were exposed to intermittent hypoxia for two weeks immediately after the last dose of capsaicin. Subsequently, pulmonary vascular function, as well as substance P (a tachykinin) level and neutral endopeptidase (NEP, the major degradation enzyme for tachykinins) activity in the lungs were measured. Chronic hypoxia caused significant increases in pulmonary artery pressure, right ventricle/(left ventricle + septum) weight ratio, hematocrit, and lung substance P level, as well as a significant decrease in lung NEP activity. All these chronic hypoxia-induced changes were significantly lessened by capsaicin pretreatment. Capsaicin pretreatment alone did not induce any significant alteration in vascular function. These results suggest that the chronic hypoxia causes an increase in lung tachykinin levels which, in turn, enhance the development of pulmonary hypertension.
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Affiliation(s)
- Y L Lai
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, ROC
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