Frequency- and state-dependent blockade of human ether-a-go-go-related gene K+ channel by arecoline hydrobromide / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The rapidly activating delayed rectifier potassium current (I(Kr)), whose pore-forming alpha subunit is encoded by the human ether-a-go-go-related gene (hERG), is a key contributor to the third phase of action potential repolarization. The aim of this study was to investigate the effect and mechanism of arecoline hydrobromide induced inhibition of hERG K(+) current (I(hERG)).</p><p><b>METHODS</b>Transient transfection of hERG channel cDNA plasmid pcDNA3.1 into the cultured HEK293 cells was performed using Lipofectamine. A standard whole-cell patch-clamp technique was used to record the I(hERG) before and after the exposure to arecoline.</p><p><b>RESULTS</b>Arecoline decreased the amplitude and the density of the I(hERG) in a concentration-dependent manner (IC(50) = 9.55 mmol/L). At test potential of +60 mV, the magnitude of I(hERG) tail at test pulse of -40 mV was reduced from (151.7 ± 6.2) pA/pF to (84.4 ± 7.6) pA/pF (P < 0.01, n = 20) and the magnitude of I(hERG) tail at test pulse of -110 mV was reduced from (-187.5 ± 9.8) pA/pF to (-97.6 ± 12.6) pA/pF (P < 0.01, n = 20). The blockade of arecoline in the open and inactivated state was significant in a state-dependent manner. The maximal blockade was achieved in the inactivated state. Studies of gating mechanism showed that the steady-state activation curve of I(hERG) was significantly negatively shifted by arecoline. Time constants of activation were shortened. Steady-state inactivation curve and time constants of fast inactivation were not significantly affected by arecoline. Furthermore, the inhibition of I(hERG) by arecoline was characterized markedly by a frequency-dependent manner from 0.03 to 1.00 Hz pulse.</p><p><b>CONCLUSION</b>Arecoline could potently block I(hERG) in both frequency and state-dependent manner.</p>

Clinical observation on children-sized fibreoptic bronchoscope usage in whole-lung lavage / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the effect of children-sized fibreoptic bronchoscope in improving the safety of whole-lung lavage (WLL).</p><p><b>METHOD</b>Patients from May 2006 to May 2010 using children-sized fibreoptic bronchoscope to assistant the location were assigned to fibreoptic bronchoscope group. Patients from May 1998 to Nov 2004 using traditional stethoscope to help intubation were assigned to control group. The adverse reactions and complications were compared.</p><p><b>RESULT</b>There were liquid leakage 1 case (0.96%), hypoxia 3 cases (2.88%) and liquid retained over 1000 ml 15 cases (14.42%) in fibreoptic bronchoscope group. In contrast, liquid leakage 24 cases (6.38%), hypoxia 42 cases (11.17%) and liquid retained over 1000 ml 135 cases (35.90%) happened in control group. The differences between the two groups were significant (P<0.05, P<0.01).</p><p><b>CONCLUSION</b>Using children-sized fibreoptic bronchoscope in WLL can promote the situation of double-lumen tube, help separation the two lungs, decrease complications and improving safety.</p>