An increase in opening of BK_(Ca) channels in smooth muscle cells in streptozotocin-induced diabetic mice  

作　　者：Chun-lingYE BingSHEN Xian-daREN Rong-jingLUO Sheng-yuanDING Fu-manYAN Jia-huaJIANG 

机构地区：[1]DepartmentofPharmacology,PharmacyCollegeofJi-nanUniversity,Guangzhou510632 [2]DepartmentofMolecularBiologyandCellBiology,SchoolofLifeSciences,UniversityofSciencesandTechnologyofChina,Hefei230036,China [3]DepartmentofPhysiology,GuangzhouUniversityofTraditionalChineseMedicine,Guangzhou510407

出　　处：《Acta Pharmacologica Sinica》2004年第6期744-750,共7页中国药理学报（英文版）

基　　金：Project supported by the National Natural Science Foundationof China (No 30070873).

摘　　要：AIM: To investigate the changes of function of large conductance of calcium-activated potassium channels (BKCa channels) in thoracic aortic smooth muscle cells in early stage of streptozotocin (STZ)-induced diabetic C57BL/6J mice. METHODS: Vascular muscle tension in the isolated thoracic aortic rings of mice was compared, and the role of BKCa channels in relaxation of isolated mice thoracic aortic rings induced by acetylcholine (ACh) was determined. Meanwhile, single vascular smooth muscle cells (VSMCs) were isolated by collagenase, and BKCa currents were recorded by patch-clamp single channel recording technique in symmetric high potassium solution. RESULTS: Tetraethylammonium (TEA) 1 mmol/L, a selective calcium-activated potassium channel blocker, caused significant rightward shift in the concentration-response curves of ACh in the isolated thoracic aortic rings of diabetic mice and pD2 value of ACh-induced relaxation was decreased notably after TEA treatment [(6.3±0.4) vs (6.9±0.5), n=10 rings from 7 mice, P<0.01]. But pD2 value of ACh-induced relaxation in age-matched control mice did not change in presence and absence of TEA 1 mmol/L [(6.4±0.15) vs (6.5±0.5), n=7 rings from 6 mice, P>0.05]. Furthermore, conductance of BKCa channels in single thoracic aortic smooth muscle cells was decreased [(199±15) pS, n=10 cells from 7 mice vs (266±11) pS, n=12 cells from 6 mice, P<0.01], but probability of open of BKCachannels was increased [(0.51±0.28) vs (0.11±0.06), n=6 cells from 6 mice, P<0.01], and the mean closed time in diabetic mice was reduced [(15±15) vs (132±98), n=6 cells from 6 mice, P<0.05]. CONCLUSION: The opening of BKCa channels was increased in thoracic aortic smooth muscle cells in the early stage of STZ-induced diabetic C57BL/6J mice by reducing mean closed time, but the conductance of BKCa channels was decreased.AIM: To investigate the changes of function of large conductance of calcium-activated potassium channels (BKCa channels) in thoracic aortic smooth muscle cells in early stage of streptozotocin (STZ)-induced diabetic C57BL/6J mice. METHODS: Vascular muscle tension in the isolated thoracic aortic rings of mice was compared, and the role of BKCa channels in relaxation of isolated mice thoracic aortic rings induced by acetylcholine (ACh) was determined. Meanwhile, single vascular smooth muscle cells (VSMCs) were isolated by collagenase, and BKCa currents were recorded by patch-clamp single channel recording technique in symmetric high potassium solution. RESULTS: Tetraethylammonium (TEA) 1 mmol/L, a selective calcium-activated potassium channel blocker, caused significant rightward shift in the concentration-response curves of ACh in the isolated thoracic aortic rings of diabetic mice and pD2 value of ACh-induced relaxation was decreased notably after TEA treatment [(6.3±0.4) vs (6.9±0.5), n=10 rings from 7 mice, P<0.01]. But pD2 value of ACh-induced relaxation in age-matched control mice did not change in presence and absence of TEA 1 mmol/L [(6.4±0.15) vs (6.5±0.5), n=7 rings from 6 mice, P>0.05]. Furthermore, conductance of BKCa channels in single thoracic aortic smooth muscle cells was decreased [(199±15) pS, n=10 cells from 7 mice vs (266±11) pS, n=12 cells from 6 mice, P<0.01], but probability of open of BKCachannels was increased [(0.51±0.28) vs (0.11±0.06), n=6 cells from 6 mice, P<0.01], and the mean closed time in diabetic mice was reduced [(15±15) vs (132±98), n=6 cells from 6 mice, P<0.05]. CONCLUSION: The opening of BKCa channels was increased in thoracic aortic smooth muscle cells in the early stage of STZ-induced diabetic C57BL/6J mice by reducing mean closed time, but the conductance of BKCa channels was decreased.

关 键 词：diabetes mellitus STREPTOZOTOCIN AORTA patch-clamp techniques potassium channels calcium 

分 类 号：R587.1[医药卫生—内分泌]