瘤胃乙∶丙酸比例对绵羊血浆胰岛素水平动态变化的影响

胰岛素是调节糖代谢的重要激素。本试验测定了向空腹绵羊瘤胃灌注混合挥发性脂肪酸和改变灌注混合挥发性脂肪酸的乙：丙酸比例之后，颈动脉血浆胰岛素水平的动态变化。结果表明，向空腹绵羊瘤胃灌注高乙：丙酸比例(75：15)的混合挥发性脂肪酸，胰岛紊水平在开始灌注后3．5h内逐渐上升，但未出现胰岛素分泌高峰。将瘤胃灌注混合挥发性脂肪酸的乙：丙酸比例改换为65：25后，血浆胰岛素水平迅速上升。在27～52min之间维持了较高水平，之后迅速下降，出现胰岛素分泌高峰。进一步提高瘤胃灌注混合挥发性脂肪酸的丙酸比例。使乙：丙酸比例达45：45，未出现胰岛素水平的动态变化。本研究结果说明，瘤胃乙：丙酸比例为75：15时。体内糖代谢调节状态与瘤胃乙：丙酸比例为65：25和45：45时不同。胰岛素对体内糖代谢的调节主要依赖于胰岛素水平在短时间的变化，而不是胰岛素水平的高低。

THE INFLUENCE OF RUMINAL ACETATE:PROPIONATE MOLAR RATIO ON PLASMA INSULIN LEVEL IN SHEEP

Insulin is one of the major hormones in adjusting cabohydrate metabolism of ruminant The present study measured jugular artery plasma insulin concentration of the sheep maintained by intragastric nutrition The liquid diet was infused into the rumen and abomasum After 7-day infusion,the sheep was fasted for 24 hours and then the sample period began In the first day,the acetate:propionate molar ratio of the volatile fatty acid mixture(VFA1) of the liquid diet was 75:15;the second day was 65:25(VFA2);the third day was 45:45(VFA3) The blood samples were extracted from jugular artery catheter at different time points after VFA1 was infused into the rumen of the fasted sheep and the volatile fatty acid mixtures were changed The results indicated that when VFA1 was infused into the rumen of the sheep fasted for 24 hours,the plasma insulin level increased smoothly and no sharp increase was detected When volatile fatty acid mixture changed from VFA1 to VFA2 in the second day,there was a sharp increase of insulin level in the first hour and then the insulin level decreased linearly In the third day,the volatile fatty acid mixture changed from VFA2 to VFA3,no dynamic changes of insulin level was observed The results implied that insulin level was influence by rumminal acetate:propionate ratio in the range form 75:15 to 65:25 As the ratio futher increased,the insulin level was not susceptible