水牛静脉注射葡萄糖后血糖水平的调节机制研究

Mechanism of plasma glucose regulation post-intravenous glucose injection in swamp buffaloes

12头健康禁食公水牛分为3组。组Ⅰ(n=6)与组Ⅱ(n=3)分别经颈静脉快速注射50%葡萄糖和0.9%生理盐水各2 mL.kg-1;组Ⅲ(n=3)为对照,不作处理。分别于注射前60、10 m in及注射后1、5、10、30、60、120、180、240、300、360和420 m in采血,立即测定血浆葡萄糖及胰岛素和胰高血糖素,分析各指标间的相关性及血浆胰岛素/血糖值(IGR1)和胰岛素/胰高血糖素值(IGR2)。结果显示:注射前,各组水牛血浆葡萄糖、胰岛素和胰高血糖素的浓度接近。组Ⅱ和组Ⅲ水牛的上述指标在所有采样时间点上组内和组间均未表现出显著性差异(P>0.05),IGR1和IGR2也没有明显变化。组Ⅰ水牛静注葡萄糖1 m in后血糖浓度迅速升至峰值,而血浆胰岛素30 m in后才升高(约20倍)至峰值,然后两者均缓慢下降,直到420 m in仍明显高于注射前的水平(P<0.05)。而胰高血糖素仅在注射葡萄糖后1和5 m in时显示出差异(P<0.05),IGR1在注射葡萄糖(组Ⅰ)后立即下降,至注射后180 m in,组Ⅰ的IGR1和IGR2与组Ⅱ和组Ⅲ的基本持平。相关性分析表明,血糖浓度与血浆胰岛素水平呈极显著正相关(r=0.73,P<0.01),与胰高血糖素浓度呈显著负相关(r=-0.58,P<0.05),但胰岛素水平与胰高血糖素浓度相关性不显著(r=0.06,P>0.05)。提示:水牛胰岛素代谢迟缓,对静注的葡萄糖清除缓慢,表现出持续性高血糖症和高胰岛素血症;水牛对于静注葡萄糖的反应不同于奶牛、犬、马等其他动物。

Twelve healthy fasted male swamp buffaloes were divided into 3 groups. Group Ⅰ , six buffaloes were subjected to 50% glucose injection quickly at a dosage of 2 mL·kg^-1 body weight via the jugular vein. Group Ⅱ, three buffaloes received normal saline. Group Ⅲ, three buffaloes were not injected. Blood samples were obtained, from the opposite vein at 60 and 10 minutes pre-administration, and at 1, 5, 10, 30, 60, 120, 180, 240, 300, 360 and 420 minutes post-glucose injection （PGI）. Plasma was harvested. Plasma glucose concentration was analyzed at once by the oxidase method. Insulin and glucagon were tested quantitatively by radioimmunoassay. The insulin/glucose ratios （IGRt） and insulin/glucagon ratios （IGR2） for each sampling time were also calculated. Mean plasma glucose, insulin and glucagon concentrations of buffaloes in Group Ⅱ and Ⅲ were similar at all the sampling times （P 〉 0. 05） and the IGR for Group Ⅱ and Group Ⅲ were flat throughout （P 〉 0. 05）. Group Ⅰ buffaloes showed an immediate 20 times increase in the mean plasma glucose concentration PGI, over the pre-administration 60 and 10 minutes. The peak plasma insulin concentration occurred at 30 minute PGI. The mean plasma glucose and insulin concentrations remained above pre-administration levels untill 420 minutes PGI （ P 〈 0. 05）. However, the mean plasma glucagon concentrations were different only at 1 and 5 minutes PGI. IGR1 for Group Ⅰ showed an initial decrease at 1 minute PGI. The values of the IGRt and IGR2 for Group I during the period of 180 to 420 minutes PGI were similar as those of Group Ⅱ and Ⅲ. The correlation analysis showed that mean plasma glucose concentration was positively correlated with insulin level （ r=0. 73, P 〈0. 01 ）, and significantly negatively correlated with mean plasma glucagon （ r=-0. 58, P 〈 0. 05 ）. Mean plasma insulin level did not show remarkable correlation with the glucagon （ r=0. 06, P 〉 0. 05 ）. The buffaloes showed an unexpected reaction to intravenous glucose loading compared with other animals, with a delayed clearance of plasma glucose and a consistent hyperglycemia and hyperinsulinemia.