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Κ-opioid receptor stimulation improves endothelial function in hypoxic pulmonary hypertension.

Wu Q, Wang HY, Li J, Zhou P, Wang QL, Zhao L, Fan R, Wang YM, Xu XZ, Yi DH, Yu SQ, Pei JM - PLoS ONE (2013)

Bottom Line: Administration of U50,488H significantly decreased mPAP and right ventricular hypertrophy as evidenced by reduction in RVP and RVHI.These effects were mediated by κ-opioid receptor.The mechanism of action might be attributed to the preservation of eNOS activity, enhancement of eNOS phosphorylation, downregulation of iNOS activity and its antioxidative/nitrative effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Chengdu Medical College, Chengdu, P.R. China.

ABSTRACT
The present study was designed to investigate the effect of κ-opioid receptor stimulation with U50,488H on endothelial function and underlying mechanism in rats with hypoxic pulmonary hypertension (HPH). Chronic hypoxia-induced HPH was simulated by exposing the rats to 10% oxygen for 2 wk. After hypoxia, mean pulmonary arterial pressure (mPAP), right ventricular pressure (RVP) and right ventricular hypertrophy index (RVHI) were measured. Relaxation of pulmonary artery in response to acetylcholine (ACh) was determined. Expression and activity of endothelial nitric oxide (NO) synthase (eNOS) and inducible NO synthase (iNOS) with NO production, total antioxidant capacity (T-AOC), gp91(phox) expression and nitrotyrosine content were measured. The effect of U50,488H administration during chronic hypoxia was investigated. Administration of U50,488H significantly decreased mPAP and right ventricular hypertrophy as evidenced by reduction in RVP and RVHI. These effects were mediated by κ-opioid receptor. In the meantime, treatment with U50,488H significantly improved endothelial function as evidenced by enhanced relaxation in response to ACh. Moreover, U50,488H resulted in a significant increase in eNOS phosphorylation, NO content in serum, and T-AOC in pulmonary artery of HPH rats. In addition, the activity of eNOS was enhanced, but the activity of iNOS was attenuated in the pulmonary artery of chronic hypoxic rats treated with U50,488H. On the other hand, U50,488H markedly blunted HPH-induced elevation of gp91(phox) expression and nitrotyrosine content in pulmonary artery, and these effects were blocked by nor-BNI, a selective κ-opioid receptor antagonist. These data suggest that κ-opioid receptor stimulation with U50,488H improves endothelial function in rats with HPH. The mechanism of action might be attributed to the preservation of eNOS activity, enhancement of eNOS phosphorylation, downregulation of iNOS activity and its antioxidative/nitrative effect.

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Concentration-dependent vasorelaxation responses to ACh (A) and NaNO2 (B) in pulmonary artery segments isolated from rats exposed to normoxia, chronic hypoxia for 2 wk and chronic hypoxia for 2 wk+U50,488H.Con: Control (normoxic group); 2 w: hypoxia for 2 wk; U50: U50,488H (1.25 mg/kg). n = 10 vascular segments/group from 5 rats. **P<0.01 vs. Con; #P<0.05, # #P<0.01 vs. 2 w.
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pone-0060850-g002: Concentration-dependent vasorelaxation responses to ACh (A) and NaNO2 (B) in pulmonary artery segments isolated from rats exposed to normoxia, chronic hypoxia for 2 wk and chronic hypoxia for 2 wk+U50,488H.Con: Control (normoxic group); 2 w: hypoxia for 2 wk; U50: U50,488H (1.25 mg/kg). n = 10 vascular segments/group from 5 rats. **P<0.01 vs. Con; #P<0.05, # #P<0.01 vs. 2 w.

Mentions: To clarify whether U50,488H could improve endothelial function, isolated pulmonary artery rings (second grade branch of pulmonary artery) in different treatment groups were collected. As shown in Figure 2A, compared with normoxic group, concentration-dependent vasorelaxation in response to ACh was blunted in pulmonary artery isolated from HPH rats (Fig. 2A). However, vasorelaxation in response to the endothelium-independent vasodilator (NaNO2) was not altererd (Fig. 2B). These results indicated that chronic hypoxia caused significant endothelial dysfunction. Most intriguingly, treatment with U50,488H for 2 weeks exerted protective roles on endothelial function, as demonstrated by a significant improvement of vasorelaxation in response to ACh.


Κ-opioid receptor stimulation improves endothelial function in hypoxic pulmonary hypertension.

Wu Q, Wang HY, Li J, Zhou P, Wang QL, Zhao L, Fan R, Wang YM, Xu XZ, Yi DH, Yu SQ, Pei JM - PLoS ONE (2013)

Concentration-dependent vasorelaxation responses to ACh (A) and NaNO2 (B) in pulmonary artery segments isolated from rats exposed to normoxia, chronic hypoxia for 2 wk and chronic hypoxia for 2 wk+U50,488H.Con: Control (normoxic group); 2 w: hypoxia for 2 wk; U50: U50,488H (1.25 mg/kg). n = 10 vascular segments/group from 5 rats. **P<0.01 vs. Con; #P<0.05, # #P<0.01 vs. 2 w.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646880&req=5

pone-0060850-g002: Concentration-dependent vasorelaxation responses to ACh (A) and NaNO2 (B) in pulmonary artery segments isolated from rats exposed to normoxia, chronic hypoxia for 2 wk and chronic hypoxia for 2 wk+U50,488H.Con: Control (normoxic group); 2 w: hypoxia for 2 wk; U50: U50,488H (1.25 mg/kg). n = 10 vascular segments/group from 5 rats. **P<0.01 vs. Con; #P<0.05, # #P<0.01 vs. 2 w.
Mentions: To clarify whether U50,488H could improve endothelial function, isolated pulmonary artery rings (second grade branch of pulmonary artery) in different treatment groups were collected. As shown in Figure 2A, compared with normoxic group, concentration-dependent vasorelaxation in response to ACh was blunted in pulmonary artery isolated from HPH rats (Fig. 2A). However, vasorelaxation in response to the endothelium-independent vasodilator (NaNO2) was not altererd (Fig. 2B). These results indicated that chronic hypoxia caused significant endothelial dysfunction. Most intriguingly, treatment with U50,488H for 2 weeks exerted protective roles on endothelial function, as demonstrated by a significant improvement of vasorelaxation in response to ACh.

Bottom Line: Administration of U50,488H significantly decreased mPAP and right ventricular hypertrophy as evidenced by reduction in RVP and RVHI.These effects were mediated by κ-opioid receptor.The mechanism of action might be attributed to the preservation of eNOS activity, enhancement of eNOS phosphorylation, downregulation of iNOS activity and its antioxidative/nitrative effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Chengdu Medical College, Chengdu, P.R. China.

ABSTRACT
The present study was designed to investigate the effect of κ-opioid receptor stimulation with U50,488H on endothelial function and underlying mechanism in rats with hypoxic pulmonary hypertension (HPH). Chronic hypoxia-induced HPH was simulated by exposing the rats to 10% oxygen for 2 wk. After hypoxia, mean pulmonary arterial pressure (mPAP), right ventricular pressure (RVP) and right ventricular hypertrophy index (RVHI) were measured. Relaxation of pulmonary artery in response to acetylcholine (ACh) was determined. Expression and activity of endothelial nitric oxide (NO) synthase (eNOS) and inducible NO synthase (iNOS) with NO production, total antioxidant capacity (T-AOC), gp91(phox) expression and nitrotyrosine content were measured. The effect of U50,488H administration during chronic hypoxia was investigated. Administration of U50,488H significantly decreased mPAP and right ventricular hypertrophy as evidenced by reduction in RVP and RVHI. These effects were mediated by κ-opioid receptor. In the meantime, treatment with U50,488H significantly improved endothelial function as evidenced by enhanced relaxation in response to ACh. Moreover, U50,488H resulted in a significant increase in eNOS phosphorylation, NO content in serum, and T-AOC in pulmonary artery of HPH rats. In addition, the activity of eNOS was enhanced, but the activity of iNOS was attenuated in the pulmonary artery of chronic hypoxic rats treated with U50,488H. On the other hand, U50,488H markedly blunted HPH-induced elevation of gp91(phox) expression and nitrotyrosine content in pulmonary artery, and these effects were blocked by nor-BNI, a selective κ-opioid receptor antagonist. These data suggest that κ-opioid receptor stimulation with U50,488H improves endothelial function in rats with HPH. The mechanism of action might be attributed to the preservation of eNOS activity, enhancement of eNOS phosphorylation, downregulation of iNOS activity and its antioxidative/nitrative effect.

Show MeSH
Related in: MedlinePlus