Ca(2+)-activated K(+) channel switching in smooth muscle participates in atherosclerosis development in diabetic rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in aorta morphology and Ca(2+)-activated K(+) (KCa) channel expression in the diabetic rats.</p><p><b>METHODS</b>A diabetic rat model was established by a single intraperitoneal injection of streptozotocin (30 mg/kg) after a modified high fat and glucose diet for 8 weeks. Pathological changes in the aorta were observed with HE staining, elastic fiber staining, Masson's trichrome staining and immunohistochemistry. Both the mRNA and protein levels of KCa channels in the aorta were measured by RT-PCR and Western blotting.</p><p><b>RESULTS</b>Early atherosclerotic changes were observed in the aorta wall of the diabetic rats. The mRNA and protein levels of KCa1.1 channel α- and β-subunits were significantly decreased, while the expression of KCa3.1 channels was obviously enhanced in the middle layer of the aorta in the diabetic rats.</p><p><b>CONCLUSION</b>KCa channel switching in smooth muscles may play a role in the development of atherosclerosis in diabetic rats.</p>

Oxidative stress impairs IKCa- and SKCa-mediated vasodilatation in mesenteric arteries from diabetic rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of oxidative stress in impaired intermediate-conductance Ca(2+)-activated potassium channels (IKCa)- and small-conductance Ca(2+)-activated potassium channels (SKCa)-mediated relaxation in diabetic resistance arteries.</p><p><b>METHODS</b>Rat diabetic model was induced by a high fat and high glucose diet and streptozotocin (STZ) injection. Endothelial function of mesenteric arteries was assessed with the use of wire myography. The expression levels of IKCa and SKCa in cultured human umbilical vein endothelial cells (HUVECs) treated with H2O2 and/or antioxidant alpha lipoic acid (ALA) were measured using Western blotting.</p><p><b>RESULTS</b>IKCa- and SKCa-mediated vasodilatation in response to acetylcholine was impaired in the third-order mesenteric arterioles of diabetic rats. In cultured HUVECs, H2O2 significantly decreased the protein expression of IKCa and SKCa. ALA alleviated the impairment of both vasodilatation function of the mesenteric arterioles ex vivo and enhanced the expression of IKCa and SKCa challenged with H2O2 in cultured HUVECs.</p><p><b>CONCLUSION</b>Our data demonstrated for the first time that impaired IKCa- and SKCa-mediated vasodilatation in diabetes was induced, at least in part, by oxidative stress via down-regulation of IKCa and SKCa channels.</p>

Inhibitory effects of blockage of intermediate conductance Ca(2+)-activated K (+) channels on proliferation of hepatocellular carcinoma cells / 华中科技大学学报（医学）（英德文版）

The roles of intermediate conductance Ca(2+)-activated K(+) channel (IKCa1) in the pathogenesis of hepatocellular carcinoma (HCC) were investigated. Immunohistochemistry and Western blotting were used to detect the expression of IKCa1 protein in 50 HCC and 20 para-carcinoma tissue samples. Real-time PCR was used to detect the transcription level of IKCa1 mRNA in 13 HCC and 11 para-carcinoma tissue samples. The MTT assay was used to measure the function of IKCa1 in human HCC cell line HepG2 in vitro. TRAM-34, a specific blocker of IKCa1, was used to intervene with the function of IKCa1. As compared with para-carcinoma tissue, an over-expression of IKCa1 protein was detected in HCC tissue samples (P<0.05). The mRNA expression level of IKCa1 in HCC tissues was 2.17 times higher than that in para-carcinoma tissues. The proliferation of HepG2 cells was suppressed by TRAM-34 (0.5, 1.0, 2.0 and 4.0 μmol/L) in vitro (P<0.05). Our results suggested that IKCa1 may play a role in the proliferation of human HCC, and IKCa1 blockers may represent a potential therapeutic strategy for HCC.

Voltage-dependent potassium channel and calcium-activated potassium channel current changes of peripheral blood T-lymphocytes from hypertensive patients in Xinjiang Kazakh / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the current changes of voltage-dependent potassium channel (Kv1.3 potassium channel) and calcium-activated potassium channel (IKCa1 potassium channel) in peripheral blood T-lymphocyte derived from hypertensive patients of Xinjiang Kazakh.</p><p><b>METHODS</b>Twenty randomly selected untreated Kazakh hypertensive patients and 20 Kazakh healthy subjects from Xinjiang were included in this study. T-lymphocytes were isolated from peripheral blood with magnetic cell sorting, the whole-cell currents of Kv1.3 and IKCa1 potassium channels were recorded with patch-clamp technique.</p><p><b>RESULTS</b>(1) The current density of Kv1.3 potassium channel was significantly higher in the hypertensive group [(280 ± 74) pA/pF (n = 39)] than that in the control group [(179 ± 51) pA/pF (n = 38), P < 0.01], while the membrane capacitance was similar between the two groups. (2) The current density of IKCa1 potassium channel was also significantly higher in the hypertensive group [(198 ± 44) pA/pF (n = 28)] than that in the control group [(124 ± 43) pA/pF (n = 26), P < 0.01], while the membrane capacitance was also similar between the two groups.</p><p><b>CONCLUSIONS</b>The T-lymphocytes Kv1.3 potassium channel and IKCa1 potassium channel current densities are higher in hypertensive patients in Xinjiang Kazakh suggesting a potential role of Kv1.3 and IKCa1 potassium channels activation in the pathophysiology of hypertension.</p>