灯盏花素在大鼠糖尿病早期对近球小管钠钾ATP酶活性的影响

Effects of breviscapine on Na^+,K^+-ATPase activity of proximal tubule in early diabetic rats

目的观察灯盏花素(Bre)在大鼠糖尿病早期对近球小管(PT)钠钾ATP酶(Na+,K+-ATPase)活性的影响以及对肾脏的保护作用。方法实验分为模型组(DM组)、灯盏花素治疗组(Bre组)和正常对照组(NC组)。前两组以链脲佐菌素(STZ,65mg·kg-1)腹腔注射建立糖尿病大鼠模型。Bre组在模型建立成功后连续4wk予腹腔注射灯盏花素20mg·kg-1.d-1,NC组和DM组则在相同的时间腹腔注射同体积的生理盐水。4wk后动物在麻醉下行双侧输尿管插管,收集尿样并行心脏穿刺取血;对一侧肾动脉进行灌注后,取肾皮质组织孵育,在显微镜下手工分离单根PT,用液闪法检测其Na+,K+-ATPase活性。检测血糖及血、尿的肌酐水平,放免法测定尿微量白蛋白、尿β2-微球蛋白(β2-MG)及血清内源性洋地黄样物质(EDLS)水平。结果NC组PT的Na+,K+-ATPase活性为(959.11±117.35)pmolPi·mm-1·h-1,DM组则明显增高达(1893.53±383.90)pmolPi·mm-1·h-1(P<0.01),Bre组为(1262.09±125.14)pmol Pi·mm-1·h-1,虽然高于NC组(P<0.05),但却明显低于DM组(P<0.05)。DM组的血清EDLS水平明显低于NC组(P<0.01),Bre组的血清EDLS水平虽然也低于NC组(P<0.05),但却高于DM组(P<0.01)。分别与NC组和DM组比较,Bre组的血糖水平明显高于NC组,而与DM组差异无显著性,除此之外,其尿量、尿β2-MG、尿白蛋白排泄率(UAER)和肌酐清除率(Ccr)都与DM组有相同性质的变化,但变化幅度都小于DM组(P<0.05)。结论Bre在大鼠糖尿病早期对肾小管Na+,K+-ATPase活性增强有限制作用,此作用的机制可能与Bre在此期间限制了EDLS释放减少的程度有关;在相同的实验条件下,Bre对大鼠糖尿病早期肾脏具有保护作用。

Aim To investigate the effects of breviscapine(Bre)on Na+,K+-ATPase activity of proximal tubule(PT) and its renal protection in early diabetic rats. Methods The rats were divided into three groups: diabetic model (DM group), Bre treatment (Bre group) and normal control (NC group). Rats were administrated with Bre(20 mg·kg-1·d-1, ip) in Bre group, with normal saline(ip) in DM and NC groups for four weeks after diabetes induction with streptozotocin (STZ 65 mg·kg-1, ip) in Bre and DM groups. The urine and blood samples were collected from two intra-ureteral cannulas and the heart, respectively, under anesthesia four weeks after diabetes induction. After one of the renal arteries being perfused, the renal cortex was incubated and PT segments were microdissected freehand under microscope before the Na+,K+-ATPase activity in the segments were assessed by liquid scintillation counter. The blood glucose, levels of creatinine in serum and in urine were assayed. The microalbumin , β2-microglobulin(β2-MG) of urine and endogenous digitalis-like substance (EDLS) of serum were measured respectively by radioimmunoassay. Results The PT Na+,K+-ATPase activity in NC group was(959.11±117.35) pmolPi·mm-1·h-1, and that in DM group was significant higher for (1893.53±383.90) pmolPi·mm-1·h-1 than it(P<0.01). That in Bre group[(1262.09±125.14) pmolPi·mm-1·h-1] was also significant higher than that in NC group(P<0.01), but was lower than that in DM group(P<0.05). The serum EDLS level in DM group was significant lower than that in NC group(P<0.01). The level of serum EDLS in Bre group decreased significantly compared with that of NC group(P<0.05),but increased significantly compared with that of DM group(P<0.01). There was no significant difference in blood glucose levels between Bre and DM groups, and that in the two groups was significant higher than that in NC group respectively. There were similar the changes of urinary flow, urinary β2-MG level, urine albumin excretion rate and creatinine clearance in Bre and in DM groups, but the extent of the changes were limited in Bre group compared with DM group(P<0.05). Conclusion The increase of Na+,K+-ATPase activity of renal tubule in early diabetic rats is able to be limited by Bre,because, at least in part, the degree of decrease in EDLS release is limited by Bre. There is renal protection of Bre in early diabetic rats under the same experiment conditions.