[Effects of propofol combined with indomethacin on contraction of isolated human pulmonary arteries].

OBJECTIVE: To investigate the effects of propofol combined with indomethacin on the contractile function of isolated human pulmonary arteries. METHODS: Human pulmonary artery preparations were obtained from patients undergoing surgery for lung carcinoma. The intrapulmonary arteries were dissected and cut into rings under microscope for treatment with propofol or propofol combined with indomethacin. In each group, the rings were divided into endothelium-intact and endothelium-denuded groups and mounted in a Multi Myograph system. In propofol group, the rings were preconstricted by U46619 to induce a sustained contraction, and propofol (10-300 mmol/L) was then applied cumulatively. In the combined treatment group, the rings were pretreated with indomethacin (100 µmol/L) for 30 min before application of U46619 to induce sustained contraction, and propofol (10-300 µmol/L) was added cumulatively after the tension became stable. RESULTS: Propofol (10-100 µmol/L) induced constrictions at low concentrations and caused relaxations at higher concentrations (100-300 µmol/L) in the pulmonary artery rings with prior U46619-induced contraction. Propofol caused stronger constrictions in endothelium-intact rings [EC50=4.525∓0.37, Emax=(30.44∓2.92)%] than in endothelium-denuded rings [EC50=4.699∓0.12, Emax=(31.19∓5.10)%, P<0.05]. Pretreatment of the rings with indomethacin abolished constrictions, and the relaxation was more obvious in endothelium-intact group [pD2=3.713∓0.11, Emax=(98.72∓0.34)%] than in endothelium- denuded group [pD2=3.54∓0.03, Emax=(94.56∓0.53)%, P<0.05]. CONCLUSION: Propofol induces constriction at low concentrations and relaxation at high concentrations in human intrapulmonary arteries with U46619-induced contraction. Indomethacin abolishes the constriction induced by propofol in isolated intrapulmonary arteries, suggesting that propofol potentiates U46619-mediated pulmonary vasoconstriction by promoting the concomitant production of prostaglandin by cyclooxygenase in pulmonary artery smooth muscle cells, and the mechanism for its relaxation effect may partly depend on the endothelium.

[Effect of resveratrol on constrictions of human intrapulmonary arteries ex vivo].

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.

[Study on the roles of voltaged potassium channels in acute hypoxic pulmonary vasoconstriction].

OBJECTIVE: To investigate the role of voltage-gated potassium channels in the acute hypoxic pulmonary vasoconstriction. METHODS: Thirty Wistar rats were divided into two groups, namely the normoxic group and hypoxic group. The single smooth muscle cell was obtained from the pulmonary artery of Wistar rats with acute enzymatic digestion method. The conventional whole-cell patch clamp technique was used to record the resting membrane potential(Em) and the potassium currents of voltage-gated potassium channel (IKv) in rat pulmonary arterial smooth muscle cells(PASMC). Intracellular application of Kv1.2, Kv1.3, Kv1.5, and Kv2.1 antibodiesè1:125éwas conducted through the whole-cell patch clamp system. RESULTS: Em of PASMC was depolarized in hypoxia compared with that of control cells. The mixture of Kv1.2, Kv1.3, Kv1.5, and Kv2.1 antibodiesè1:125é depolarized Em and inhibited Ikv in PASMC from normoxic rat,whereas the mixture of Kv1.2, Kv1.3, Kv1.5, Kv2.1 antibodiesè1:125éhad no effects on Ikv and Em in hypoxic rats. CONCLUSION: Kv1.2, Kv1.3, Kv1.5, Kv2.1 might be oxygen sensitive potassium channels which mediated acute hypoxic pulmonary vasoconstriction.

[Analysis of the association between double-lumen endobronchial tube and inner diameter of the left main bronchus].

OBJECTIVE: To investigate the association of the left double-lumen endobronchial tube (DLT) and the inner diameter of the left main bronchus. METHODS: Totally 100 adult patients who required intubation of a left-sided DLT during anesthesia for elective thoracic surgery were randomly enrolled in this study. All the participants underwent a preoperative chest CT scan by a spiral CT scanner. The diameters of the trachea and left main bronchus were measured with three-dimensional image reconstruction technique. All the measurements were performed using the electronic calipers of the spiral CT scanner and the left-sided DLT (Portex SIMS, USA) of the sizes 41Fr, 39Fr, 37Fr, and 35Fr were selected, being predicted according to the inner diameter of the left main bronchus. The placement of DLT was performed after anesthesia induction, and a DLT of a smaller size was selected if the bronchial end of the DLT failed to enter the left main bronchus after two attempts. The trachea and left main bronchus were examined for injury and other complications with postoperative fibreoptic bronchoscopy (FOB). RESULTS: All the 100 patients were intubated with DLT of appropriate sizes and satisfactory lung isolation was achieved. Postoperative complications of the trachea and bronchus were observed in none of the patients with FOB examination. The appropriate size of DLT is correlated with the left main bronchial diameter (correlation coefficient r=0.7346). CONCLUSION: Clinically, the size of DLT can be determined in accordance with the inner diameter of the left main bronchea.