摘要
目的：探讨二十二碳六烯酸（DHA）对糖尿病大鼠冠状动脉平滑肌细胞大电导钙激活钾通道（BK通道）开放概率（NP0）的影响。方法选取体重（200±20）g，年龄6-8周的雄性SD大鼠20只为研究对象，采用随机数字表法分为糖尿病组（10只）和正常对照组（10只）。糖尿病组采用链脲霉素腹腔内注射，2周后测定大鼠血糖浓度，如血糖浓度低于300 mg/dl，则用等剂量链脲霉素再次腹腔内注射，当血糖浓度持续8周高于300 mg/dl视为造模成功。正常对照组大鼠腹腔内注射生理盐水。酶消化法急性分离正常和糖尿病大鼠冠状动脉平滑肌细胞，单通道膜片钳实验技术记录正常和糖尿病大鼠冠状动脉平滑肌细胞BK通道电流并比较不同浓度DHA作用下正常和糖尿病大鼠冠状动脉平滑肌细胞BK通道NP0。两两比较采用t检验，组间比较采用单因素方差分析。结果当刺激电压为0、20、40、60、80、100、120 mV时，随着刺激电压增加，正常对照组和糖尿病组BK通道NP0均增加（F=15.28、9.72，均P〈0.05）。与正常对照组相比，当刺激电压〉60 mV后，糖尿病组BK通道NP0明显降低（分别为0.56±0.05比0.22±0.02，1.11±0.09比0.33±0.09，2.85±0.10比0.86±0.12，3.05±0.15比1.01±0.13， t=3.62、4.27、6.32、8.14，均P〈0.05）。在刺激电压60 mV和钙离子浓度1mmol/L条件下，当电极外液DHA浓度为0、0.01、0.10、0.30、1.00mmol/L时，正常对照组和糖尿病组BK通道NP0均无明显增加（F=3.01、2.61，均P〉0.05）；继续增加DHA的浓度，当DHA浓度为3、5、10mmol/L时，对照组BK通道NP0呈浓度依赖性增加，糖尿病组NP0呈浓度依赖性增加（F=10.21、7.32，均P〈0.05）。在DHA浓度相同情况下，糖尿病组BK通道NP0均低于对照组（t=2.71-8.54，均P〈0.05）。结论糖尿病大鼠冠状动脉平滑肌细胞BK通道功能受损，但DHA仍可激活BK通道，增加NP0，从而扩张冠状动脉而起保护作用。
Objective To investigate the effects of docosahexaenoic acid （DHA） on large conductance Ca2＋？activated K＋channel （BK channel） open probabilities （NP0） in coronary smooth muscle cells of diabetic rats. Methods Streptozotocin-induced diabetic rat animal model was established by injection intraperitoneally. Male SD rats （n=20） with weight of （200±20） g and age of 6？8 weeks were divided into diabetic group （n=10） and normal control group （n=10） by random number table method. Diabetic group was injected intraperitoneally with streptozotocin. Blood glucose was tested after 2 weeks. If it was less than 300 mg/dl, same dose streptozotocin was injected intraperitoneally again. Diabetes was diagnosed until blood glucose was more than 300 mg/dl for 8 weeks. The control group was injected by normal saline. Coronary smooth muscle cells in control and diabetic rats were isolated immediately by enzyme digestion method. The BK currents in coronary smooth muscle cells of control and diabetic group were recorded by single channel patch？clamp technique. Effects of DHA on NP0 of BK channels in coronary smooth muscle cells of control and diabetic rats were compared. Student t test or Wilcoxon rank test were used to compare the NP0 between control and diabetic groups. One？way ANOVA or M test were applied to compare the NP0 in different DHA concentrations groups. Results When test potentials were at 0, 20, 40, 60, 80, 100, 120 mV, NP0 of BK channels increased with test potentials in both control and diabetic group （F=15.28, 9.72, all P〈0.05）. After test potentials above 60 mV, the NP0 of BK channels in diabetic group were significantly decreased （t=3.62？8.14, all P〈0.05）. At 0, 0.01, 0.10 , 0.30, 1.00mmol/L DHA, DHA failed to activate BK channels in both control and diabetic group under 60 mV voltage and 1mmol/L Ca＋（F=3.02,2.61, all P〉0.05）. At 3, 5 and 10 mmol/L, DHA activated BK channels in a dose？dependent manner in both control group and diabetic group （F=10.21 ,7.32, all P〈0.05）. The NP0 were lower in diabetic group than in control group at the same DHA concentrations （t=2.71？8.54, all P〈0.05）. Conclusion BK tunnel capacity of the coronary smooth muscle cells in diabetic rats was impared. The protective effects of DHA on diabetic heart may be performed by activating BK channels, increasing NP0 and dilating coronary arteries.
出处
《中华糖尿病杂志》
CAS
CSCD
2015年第8期513-517,共5页
CHINESE JOURNAL OF DIABETES MELLITUS
基金
国家自然科学基金（81070157、81370303）
江苏省自然科学基金（BK2011179）
江苏省人事厅“六大人才高峰”第七批高层次项目（006）
江苏省医学重点人才资助项目（RC201134）
关键词
二十二碳六烯酸
糖尿病
冠状动脉
大电导钙离子激活钾通道
膜片钳
Docosahexaenoic acid
Diabetes mellitus
Coronary artery
Large conductance Ca^2＋-activated K^＋channel
Patch-clamp
作者简介
通信作者：王如兴，Email：ruxingw@aliyun．com
