Effect of α-Methyldopa on the Pulmonary Vascular Changes Induced by Chronic Hypoxia in Rats

1977 ◽  
Vol 53 (4) ◽  
pp. 397-400 ◽  
Author(s):  
A. J. Suggett ◽  
J. Herget
Keyword(s):  
Pulmonary Artery ◽  
Right Ventricular ◽  
Pulmonary Artery Pressure ◽  
Ventricular Hypertrophy ◽  
Chronic Hypoxia ◽  
Distilled Water ◽  
Vascular Changes ◽  
Histological Changes ◽  
Pulmonary Vessels ◽  
And Control

1. Groups of young rats were kept in a hypoxic chamber or in air as control animals for 28 days. 2. Hypoxic and control animals were treated with either α-methyl-3,4-dihydroxyphenylalanine (α-methyldopa) or distilled water. 3. α-Methyldopa significantly reduced the increase in pulmonary artery pressure and right ventricular hypertrophy induced by chronic hypoxia and partially prevented the histological changes in the small pulmonary vessels.

Angiotensin II prevents hypoxic pulmonary hypertension and vascular changes in rat

1988 ◽  
Vol 254 (3) ◽  
pp. H500-H508 ◽  
Author(s):  
M. Rabinovitch ◽  
M. Mullen ◽  
H. C. Rosenberg ◽  
K. Maruyama ◽  
H. O'Brodovich ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Angiotensin Ii ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Pulmonary Artery Pressure ◽  
Ventricular Hypertrophy ◽  
Right Ventricular Hypertrophy ◽  
Vascular Changes ◽  
Hypoxic Pulmonary Hypertension ◽  
Artery Pressure

Angiotensin II, a vasoconstrictor, has been previously demonstrated to produce a secondary vasodilatation due to release of prostaglandins. Because of this effect, we investigated whether infusion of exogenous angiotensin II via miniosmopumps in rats during a 1-wk exposure to chronic hypobaric hypoxia might prevent pulmonary hypertension, right ventricular hypertrophy, and vascular changes. We instrumented the rats with indwelling cardiovascular catheters and compared the hemo-dynamic and structural response in animals given angiotensin II, indomethacin in addition to angiotensin II (to block prostaglandin production), or saline with or without indomethacin. We then determined whether angiotensin II infusion also prevents acute hypoxic pulmonary vasoconstriction. We observed that exogenous angiotensin II infusion abolished the rise in pulmonary artery pressure, the right ventricular hypertrophy, and the vascular changes induced during chronic hypoxia in control saline-infused rats with or without indomethacin. The protective effect of angiotensin II was lost when indomethacin was given to block prostaglandin synthesis. During acute hypoxia, both angiotensin II and prostacyclin infusions similarly prevented the rise in pulmonary artery pressure observed in saline-infused rats and in rats given indomethacin or saralasin in addition to angiotensin II. Thus exogenous angiotensin II infusion prevents chronic hypoxic pulmonary hypertension, associated right ventricular hypertrophy, and vascular changes and blocks acute hypoxic pulmonary hypertension, and this is likely related to its ability to release vasodilator prostaglandins.

Possible role of pulmonary blood volume in chronic hypoxic pulmonary hypertension

1993 ◽  
Vol 74 (6) ◽  
pp. 3020-3026 ◽  
Author(s):  
L. C. Ou ◽  
G. L. Sardella ◽  
N. S. Hill ◽  
C. D. Thron
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Blood Volume ◽  
Ventricular Hypertrophy ◽  
Chronic Hypoxia ◽  
Right Ventricular Hypertrophy ◽  
Hypoxic Pulmonary Hypertension ◽  
Pulmonary Blood Volume

Chronic hypoxia increases the total blood volume (TBV) and pulmonary arterial blood pressure (Ppa) and induces pulmonary vascular remodeling. The present study was undertaken to assess how the pulmonary blood volume (PBV) changes during hypoxia and the possible role of PBV in chronic hypoxic pulmonary hypertension. A novel method has been developed to measure the TBV, PBV, and Ppa in conscious rats. The method consists of chronic implantation of a loose ligature around the ascending aorta and pulmonary artery, so that when the ligature is drawn tightly, it traps the blood in the pulmonary vessels and left heart and simultaneously kills the rat. The pulmonary veins are then ligated to separate the left ventricular blood volume from the PBV. This surgical approach, together with chronic catheterization of the pulmonary artery and the use of 51Cr-labeled red blood cells, allows measurement of TBV, PBV, and Ppa. This method has been used to analyze the relationships between TBV and PBV and between Ppa or right ventricular hypertrophy and PBV in two rat strains with markedly different TBV and Ppa responses to chronic hypoxia. PBV per given lung weight did not increase and even decreased during hypoxia despite marked increases in TBV. There was a close correlation between Ppa or right ventricular hypertrophy and PBV in the two strains of chronically hypoxic animals, suggesting that a greater PBV plays a significant role in the development of severe chronic hypoxic pulmonary hypertension in the altitude-susceptible Hilltop rats.

scholarly journals Parathyroid hormone affects right heart hemodynamics and exacerbates pulmonary hypertension

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
Y J Joki ◽  
H K Konishi ◽  
K T Takasu ◽  
T M Minamino
Keyword(s):  
Pulmonary Hypertension ◽  
Parathyroid Hormone ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Pulmonary Artery Pressure ◽  
Ventricular Hypertrophy ◽  
Right Ventricular Hypertrophy ◽  
Right Heart ◽  
Pulmonary Hemodynamics ◽  
Artery Pressure

Abstract Background Pulmonary hypertension (PH) is characterized by increased pulmonary artery pressure and develops right heart failure. Parathyroid hormone (PTH) is secreted from parathyroid gland and regulates a calcium homeostasis. Recent studies have suggested that PTH also acts on the cardiovascular system and affects cardiovascular prognosis. We hypothesized that PTH would play a role in the pathogenesis of PH. Purpose This study aimed to investigate the effect of PTH on pulmonary hemodynamics. Method We measured serum PTH levels in patients who were suspected of PH and underwent right heart catheter examination. We used two types of PH animal models, hypoxia (Hx)-induced PH mouse model and Sugen/hypoxia (SuHx)-induced PH rat model. Hx mice were administered PTH daily for 3 weeks. SuHx rats underwent parathyroidectomy, after which they received SuHx treatment for 10weeks. We measured physical data and right ventricular systolic pressure (RVSP) in these models. We cultured pulmonary artery smooth muscle cell (PASMC) treated with PTH to analyze cell signaling, proliferation and migration. Result We enrolled 20 participants. PTH concentration was significantly correlated with mean pulmonary artery pressure (r=0.58, p=0.006) as well as with pulmonary vascular resistance (r=0.61, p=0.04). Receiver operating characteristic curve displayed a cut-off PTH level of 48.0pg/ml that offered optimal differentiation between patients with and without PH (100% sensitivity, 73% specificity). PTH treatment exacerbated right ventricular hypertrophy and increased RVSP (33.6mmHg vs. 48.2mmHg) in Hx mice compared with non-treated Hx mice (Figure 1). Conversely, parathyroidectomy significantly attenuated right ventricular hypertrophy and reduced RVSP (54.2mmHg vs. 29.3mmHg) in SuHx rats compared with sham-operated SuHx rats. PTH promoted migration and proliferation through ERK signaling in PASMC. Conclusion Our clinical and experimental data demonstrated a critical role of PTH in the development of PH and suggested that PTH would be a novel therapeutic target for PH treatment. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Young Scientists Figure 1. PTH treatment exacerbated RVSP

Abstract 15303: Dimethylarginine Dimethylaminohydrolase-1 is Not Involved in Chronic Hypoxic Pulmonary Hypertension and Right Ventricular Hypertrophy in Mice

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Juliane Hannemann ◽  
Antonia Glatzel ◽  
Jonas Hillig ◽  
Julia Zummack ◽  
Rainer H Boeger
Keyword(s):  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
Ventricular Hypertrophy ◽  
Chronic Hypoxia ◽  
Right Ventricular Hypertrophy ◽  
Cardiomyocyte Hypertrophy ◽  
No Production ◽  
Knock Out ◽  
Knock Out Mice ◽  
Adma Concentration

Introduction: Chronic hypoxia causes persistent pulmonary vasoconstriction and leads to pulmonary hypertension and right ventricular hypertrophy. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthesis; its level increases in hypoxia concomitantly with reduced activity of dimethylarginine dimethylaminohydrolases (DDAH-1 and DDAH-2), the enzymes metabolizing ADMA. DDAH knockout models may therefore help to understand the pathophysiological roles of this enzyme and its substrate, ADMA, in the development of hypoxia-associated pulmonary hypertension. Hypothesis: We hypothesized that DDAH1 knock-out mice have an attenuated hypoxia-induced elevation of ADMA and reduced right ventricular hypertrophy. Methods: DDAH1 knock-out mice (KO) and their wild-type littermates (WT) were subjected to normoxia (NX) or hypoxia (HX) during 21 days. We measured ADMA concentration in plasma, DDAH1 and DDAH2 expression in the lung, right ventricular hypertrophy by the Fulton index, cardiomyocyte hypertrophy by dystrophin staining of heart tissues, and muscularization of pulmonary arterioles by CD31 and α-actin staining of lung sections. Results: DDAH1 KO mice had higher ADMA concentration than WT under NX (2.31±0.33 μmol/l vs. 1.20±0.17 μmol/l; p < 0.05). ADMA significantly increased in WT-HX (to 1.74±0.86 μmol/l; p < 0.05 vs. normoxia), whilst it did not further increase in KO-HX (2.58±0.58 μmol/l; p = n.s.). This was paralleled by a 38±13% reduction in DDAH1 mRNA but not DDAH2 mRNA expression, and reduced DDAH protein expression. We observed right ventricular hypertrophy under hypoxia in both, WT and KO mice, with no significant differences between both genotypes. Further, cardiomyocyte hypertrophy and pulmonary arteriolar muscularization were significantly increased by hypoxia, but not significantly different between WT and KO mice. Conclusions: We conclude that chronic hypoxia causes an elevation of ADMA, which impairs NO production and leads to endothelial dysfunction and vasoconstriction. Downregulation of DDAH expression and activity may be involved in this; however, knockout of DDAH1 does not modify the pathophysiological changes in remodeling of the pulmonary vasculature and the right ventricle.

Humoral regulation of vascular resistance after 30 days of pulmonary artery constriction

1979 ◽  
Vol 236 (6) ◽  
pp. H866-H872 ◽  
Author(s):  
R. F. McNamara ◽  
P. G. Schmid ◽  
J. A. Schmidt ◽  
D. D. Lund ◽  
R. K. Bhatnagar
Keyword(s):  
Angiotensin Ii ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Vascular Resistance ◽  
Guinea Pigs ◽  
Ventricular Hypertrophy ◽  
Adrenergic Blockade ◽  
Flow Curves ◽  
Pulmonary Artery Constriction ◽  
Humoral Regulation

In an earlier study of guinea pigs with constriction of the pulmonary artery (PA) for 30 days, hindquarters' vascular resistance was maintained primarily by humoral mechanisms. In the present study, we investigated the contribution of circulating catecholamines, angiotensin II, and other constrictor stimuli to hindquarters' vascular resistance by observing vasodilator responses to specific competitive antagonists. Pressure-flow curves indicated vascular resistances in isolated, perfused, sympathectomized hindquarters of anesthetized guinea pigs. Phentolamine produced significantly greater (P less than 0.05) vasodilatation in animals with constriction of pulmonary artery than in sham animals [Sar1-Ala8]angiotensin II produced no vasodilation in either group. After alpha-adrenergic blockade, papaverine produced similar vasodilatation and similar final perfusion pressures in both groups. It appears that circulating catecholamines and augmented vasoconstrictor responsiveness to norepinephrine are totally responsible for the increased humoral regulation of vascular resistance in this experimental model of right ventricular hypertrophy.

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