title: [Changes of open probability of large conductance Ca(2+)-activated K(+) channels in diabetic coronary smooth muscle cells of rats].
abstract: OBJECTIVE
  To investigate the changes of open probability (Po) of large conductance Ca(2+)-activated K(+) channel (BK channel) in diabetic coronary smooth muscle cells and elucidate the underlying cellular electrophysiology mechanisms of coronary dysfunction.
  
  
  METHODS
  Rat coronary smooth muscle cells were isolated from control group and diabetic group. BK single channel currents were recorded by patch clamp technique in inside-out configuration. Open probabilities were calculated and compared between two groups. After exposure to DHS-1, a specific BK channel activator, Po at 0.2 and 1 µmol/L free Ca(2+) were compared between control and diabetic groups.
  
  
  RESULTS
  In the presence of 0.2 µmol/L free Ca(2+), the Po at baseline was significantly lower in diabetic rats than in control rats (0.0032 ± 0.0012 vs. 0.095 ± 0.036, P < 0.05). Cytoplasmic application of DSH-1 significantly increased the Po to 0.335 ± 0.096 (P < 0.05 vs. baseline) in control rats, whereas DSH-1 had no effect in diabetic rats (Po = 0.022 ± 0.018, P > 0.05 vs. baseline). In the presence of 1 µmol/L free Ca(2+), the Po at baseline was also significantly lower in diabetic rats than in control rats (0.210 ± 0.055 vs. 0.458 ± 0.077, P < 0.05). Cytoplasmic application of DHS-1 further robustly enhanced Po to 0.823 ± 0.019 (P < 0.05 vs. baseline) in control rats and to 0.446 ± 0.098 in diabetic rats (P < 0.05 vs. baseline of diabetic rats; P < 0.05 vs. control rats with DHS-1).
  
  
  CONCLUSIONS
  The decrease of Po of BK single channel in coronary smooth muscle cells may be a potential cause for coronary dysfunction in diabetic rats.
authors.affiliation: Department of Cardiology, Nanjing Medical University, Wuxi, China. ruxingw@yahoo.com.cn
authors.forename: Ru-xing
authors.initials: RX
authors.lastname: Wang
authors.forename: Zhi-ming
authors.initials: ZM
authors.lastname: Yu
authors.forename: Chang-ying
authors.initials: CY
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Zheng
authors.forename: Ku-lin
authors.initials: KL
authors.lastname: Li
authors.forename: Yun-lai
authors.initials: YL
authors.lastname: Gao
authors.forename: Ying-fang
authors.initials: YF
authors.lastname: Bao
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
authors.forename: Yong
authors.initials: Y
authors.lastname: Yao
authors.forename: Xiao-rong
authors.initials: XR
authors.lastname: Li
authors.forename: Tong
authors.initials: T
authors.lastname: Lu
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000378:metabolism / Q000503:physiopathology; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000503:physiopathology; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000503:physiopathology*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D051036:Large-Conductance Calcium-Activated Potassium Channels