磷酸二酯酶抑制剂诱导的大鼠胰岛素抵抗对糖脂代谢的影响

目的:探讨选择性磷酸二酯酶III(PDE₃)抑制剂米力农(milrinone)对大鼠胰岛素分泌、血糖、血浆游离脂肪酸(FFA)的影响和剂量依赖关系,及其在胰岛素钳夹状态下对大鼠糖代谢和胰岛素敏感性的影响。方法:由植入导管给予大鼠不同剂量的米力农(1、5、25μmol/kg)在不同时相测定血糖、血浆FFA和胰岛素水平并与对照组比较。在清醒状态下建立大鼠高胰岛素-正常血糖钳夹技术,并在钳夹120min时分别经导管给予米力农(25μmol/kg)和25%二甲基亚砜(DMSO,对照组)。采用气相色谱-质谱仪(GC-MS)测定糖代谢率。结果:3个不同剂量米力农组血浆FFA浓度明显高于对照组和给药前,在注射后2min,各组FFA升高的百分数为:50%、52%、55%(1、5、25μmol/kg)。在5、25μmol/kg组血浆胰岛素水平也明显高于对照组和给药前,仅25μmol/kg组血糖浓度高于对照组和给药前。在胰岛素钳夹研究中,米力农处理组大鼠血浆FFA明显高于给药前,肝糖输出(HGP)也明显高于给药前。葡萄糖输注率(GIR)明显低于对照组和给药前。结论:米力农损害了胰岛素抑制脂解和肝糖输出的能力及胰岛素介导的外周组织糖的利用。因此,米力农处理可能在体内诱导了一个急性胰岛素抵抗。

Effects of phosphodiesterase inhibitor- induced insulin resistance on glucose and lipid metabolism in rats

AIM:To investigate the effects of milrinone (a selective phosphdiesterase III inhibitor PDE₃) on insulin secretion, blood glucose, plasma free fatty acids (FFA) and dose-response relationship, and assess possible effects of milrinone on glucose metabolism and insulin sensitivity in conscious rats.METHODS:The catheterized nonstressed rats were administered by the varying doses of milrinone (1, 5, 25 μmol/kg) and were compared with controls. A hyperinsulinaemic- euglycaemic clamp was established in awake rats, and milrinone(25 μmol/kg) and 25% dimethyl sulfoxide (DMSO, as a control) were given at 120 min during hyperinsulinaemic- euglycaemic clamp. Glucose turnover was decided by gas chromatograph mass spectrometer (GC-MS).RESULTS:After dosing, plasma FFA levels in 3 milrinone groups significantly increased compared with the controls and before dosing. The percentages of elevation of FFA by the different milrinone doses were very similar, 50%, 52%, 55% for 1, 5, 25 μmol/kg respectively at 2 min after dosing. Plasma insulin levels were significantly elevated in the 5 and 25 μmol/kg groups, and the effect of milrinone on glucose concentration was detectable only 25 μmol/kg group. During hyperinsulinaemic clamp, there were significant increase in plasma FFA (from 173.1±15.2 to 633.8±87.3 μEq/L) and hepatic glucose production (HGP), and a significant decrease in glucose infusion rates (GIR) (to about 21%).CONCLUSION:These data suggest that milrinone impaires the abilities of insulin to suppress lipolysis and HGP, and insulin-mediated glucose utilization in peripheral tissue. Therefore, milrinone administration may induce an acute insulin resistancein vivo.