Objective To investigate the effect of dexmedetomidine on 5- HT- induced constrictions of isolated human intrapulmonary arteries and explore the mechanisms. Methods Lung tissue was obtained from patients undergoing surgery for lung carcinoma. Intrapulmonary arteries were dissected and cut into rings, which were mounted in a Multi Myograph system to determine the effect of dexmedetomidine (0.3-3 nmol/L) on 5-HT-induced vasoconstractions. The influences of the endothelium removal and various drugs including L-NAME, yohimbine and indomethacin were tested on the effects of dexmedetomidine. Results Dexmedetomidine (0.1-100 nmol/L) did not obviously affect the resting tension of endothelium-intact human intrapulmonary arteries. 5- HT induced concentration- dependent contraction in endothelium- intact intrapulmonary arteries[pD2:6.11 ± 0.05, Emax:(102.10 ± 1.96)%]. In the rings with intact endothelium, dexmedetomidine (0.3-3 nmol/L) significantly attenuated the Emax and pD2 of 5-HT-induced vasoconstriction[pD2:5.94±0.03, Emax:(79.96±1.31)%]. 5-HT also induced concentration-dependent contraction in endothelium-denuded intrapulmonary arteries [pD2: 6.10 ± 0.07, Emax:(107.40 ± 3.20)%]. Dexmedetomidine produced no significant effects on the rings with denuded endothelium. The effects of dexmedetomidine on 5-HT-induced vasoconstriction was suppressed by L-NAME and yohimbine, but not by indomethacin. Conclusion Dexmedetomidine can inhibit 5-HT-induced vasoconstriction of isolated human intrapulmonary arteries probably throughα2-adrenergic acceptor and NO released from the endothelium.

Objective To investigate the effect of dexmedetomidine on 5- HT- induced constrictions of isolated human intrapulmonary arteries and explore the mechanisms. Methods Lung tissue was obtained from patients undergoing surgery for lung carcinoma. Intrapulmonary arteries were dissected and cut into rings, which were mounted in a Multi Myograph system to determine the effect of dexmedetomidine (0.3-3 nmol/L) on 5-HT-induced vasoconstractions. The influences of the endothelium removal and various drugs including L-NAME, yohimbine and indomethacin were tested on the effects of dexmedetomidine. Results Dexmedetomidine (0.1-100 nmol/L) did not obviously affect the resting tension of endothelium-intact human intrapulmonary arteries. 5- HT induced concentration- dependent contraction in endothelium- intact intrapulmonary arteries[pD2:6.11 ± 0.05, Emax:(102.10 ± 1.96)%]. In the rings with intact endothelium, dexmedetomidine (0.3-3 nmol/L) significantly attenuated the Emax and pD2 of 5-HT-induced vasoconstriction[pD2:5.94±0.03, Emax:(79.96±1.31)%]. 5-HT also induced concentration-dependent contraction in endothelium-denuded intrapulmonary arteries [pD2: 6.10 ± 0.07, Emax:(107.40 ± 3.20)%]. Dexmedetomidine produced no significant effects on the rings with denuded endothelium. The effects of dexmedetomidine on 5-HT-induced vasoconstriction was suppressed by L-NAME and yohimbine, but not by indomethacin. Conclusion Dexmedetomidine can inhibit 5-HT-induced vasoconstriction of isolated human intrapulmonary arteries probably throughα2-adrenergic acceptor and NO released from the endothelium.

Objective To determine the effect of resveratrol on constrictions of isolated human intrapulmonary arteries and its mechanisms. Methods Intrapulmonary arteries (1-1.5 mm in diameter) were dissected and cut into rings (1.8-2.0 mm in length) under microscope, and were then mounted in a Multi Myograph system. The rings were stimulated with 100 nmol/L U46619, 30 nmol/L endothelin-1, or 60 mmol/L KCl to produce sustained contraction of the intrapulmonary arteries, after which resveratrol was applied cumulatively. Endothelium denudation, L-NAME and indomethecin were used to investigate the effect of resveratrol on constrictions of the isolated arteries, suing DMSO as the control. Results Resveratrol induced concentration-dependent relaxations in endothelium-intact rings that contracted in response to stimulations with U46619, ET-1 and KCl, with pD2 of 3.82 ± 0.20, 3.84 ± 0.57, and 3.68 ± 0.27, Emax of (99.58 ± 0.83)%, 100%, and (99.65 ± 0.98)%, respectively. Treatment of the arterial rings with the eNOS inhibitor L-NAME, but not with indomethecin or endothelium denudation, obviously affected the relaxant effects of resveratrol. Conclusion Resveratrol can concentration-dependently produce relaxant effect on human intrapulmonary arteries independent of the endothelium possibly by promoting synthesis and release of NO.

Objective To determine the effect of resveratrol on constrictions of isolated human intrapulmonary arteries and its mechanisms. Methods Intrapulmonary arteries (1-1.5 mm in diameter) were dissected and cut into rings (1.8-2.0 mm in length) under microscope, and were then mounted in a Multi Myograph system. The rings were stimulated with 100 nmol/L U46619, 30 nmol/L endothelin-1, or 60 mmol/L KCl to produce sustained contraction of the intrapulmonary arteries, after which resveratrol was applied cumulatively. Endothelium denudation, L-NAME and indomethecin were used to investigate the effect of resveratrol on constrictions of the isolated arteries, suing DMSO as the control. Results Resveratrol induced concentration-dependent relaxations in endothelium-intact rings that contracted in response to stimulations with U46619, ET-1 and KCl, with pD2 of 3.82 ± 0.20, 3.84 ± 0.57, and 3.68 ± 0.27, Emax of (99.58 ± 0.83)%, 100%, and (99.65 ± 0.98)%, respectively. Treatment of the arterial rings with the eNOS inhibitor L-NAME, but not with indomethecin or endothelium denudation, obviously affected the relaxant effects of resveratrol. Conclusion Resveratrol can concentration-dependently produce relaxant effect on human intrapulmonary arteries independent of the endothelium possibly by promoting synthesis and release of NO.

OBJECTIVETo investigate the effect of dexmedetomidine on 5-HT-induced constrictions of isolated human intrapulmonary arteries and explore the mechanisms.

METHODSLung tissue was obtained from patients undergoing surgery for lung carcinoma. Intrapulmonary arteries were dissected and cut into rings, which were mounted in a Multi Myograph system to determine the effect of dexmedetomidine (0.3-3 nmol/L) on 5-HT-induced vasoconstrictions. The influences of the endothelium removal and various drugs including L-NAME, yohimbine and indomethacin were tested on the effects of dexmedetomidine.

RESULTSDexmedetomidine (0.1-100 nmol/L) did not obviously affect the resting tension of endothelium-intact human intrapulmonary arteries. 5-HT induced concentration-dependent contraction in endothelium-intact intrapulmonary arteries [pD2: 6.11∓0.05, Emax: (102.10∓1.96)%]. In the rings with intact endothelium, dexmedetomidine (0.3-3 nmol/L) significantly attenuated the Emax and pD2 of 5-HT-induced vasoconstriction [pD2: 5.94∓0.03, Emax: (79.96∓1.31)%]. 5-HT also induced concentration-dependent contraction in endothelium-denuded intrapulmonary arteries [pD2: 6.10∓0.07, Emax: (107.40∓3.20)%]. Dexmedetomidine produced no significant effects on the rings with denuded endothelium. The effects of dexmedetomidine on 5-HT-induced vasoconstriction was suppressed by L-NAME and yohimbine, but not by indomethacin.

CONCLUSIONDexmedetomidine can inhibit 5-HT-induced vasoconstriction of isolated human intrapulmonary arteries probably through α2-adrenergic acceptor and NO released from the endothelium.

Adult ; Aged ; Dexmedetomidine ; pharmacology ; Female ; Humans ; In Vitro Techniques ; Male ; Middle Aged ; Pulmonary Artery ; drug effects ; Serotonin ; pharmacology ; Vasoconstriction ; drug effects

Despite the complex vascular effects of dexmedetomidine (DEX), its actions on human pulmonary resistance arteries remain unknown. The present study tested the hypothesis that DEX inhibits vascular tension in human pulmonary arteries through the endothelial nitric oxide synthase (eNOS) mediated production of nitric oxide (NO). Pulmonary artery segments were obtained from 62 patients who underwent lung resection. The direct effects of DEX on human pulmonary artery tension and changes in vascular tension were determined by isometric force measurements recorded on a myograph. Arterial contractions caused by increasing concentrations of serotonin with DEX in the presence or absence of L-NAME (endothelial nitric oxide synthase inhibitor), yohimbine (α2-adrenoceptor antagonist) and indomethacin (cyclooxygenase inhibitor) as antagonists were also measured. DEX had no effect on endothelium-intact pulmonary arteries, whereas at concentrations of 10⁻⁸~10⁻⁶ mol/L, it elicited contractions in endothelium-denuded pulmonary arteries. DEX (0.3, 1, or 3×10⁻⁹ mmol/L) inhibited serotonin-induced contraction in arteries with intact endothelium in a dose-dependent manner. L-NAME and yohimbine abolished DEX-induced inhibition, whereas indomethacin had no effect. No inhibitory effect was observed in endothelium-denuded pulmonary arteries. DEX-induced inhibition of vasoconstriction in human pulmonary arteries is mediated by NO production induced by the activation of endothelial α₂-adrenoceptor and nitric oxide synthase.
Arteries ; Dexmedetomidine* ; Endothelium ; Humans ; Indomethacin ; Lung ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Nitric Oxide Synthase ; Nitric Oxide Synthase Type III* ; Pulmonary Artery ; Serotonin ; Vasoconstriction* ; Yohimbine