Chase L E, Wangsness P J, Martin R J
J Dairy Sci. 1977 Mar;60(3):410-5. doi: 10.3168/jds.S0022-0302(77)83880-0.
Four Holstein steers surgically prepared with a device for sampling blood from the portal vein were used to study changes in metabolites and insulin of portal blood associated with spontaneous meal feeding. The animals were fed a complete mixed ration (3.4 kcal/g digestible energy) in individual, electronically controlled feeding units. Blood was sampled before, during, and after meals. During the meal, blood samples were at 2-min intervals. Blood was sampled at 50 individual meals. Average meal length was 15.0 min and average consumption per meal was 631.7 g. Portal insulin increased within 2 min of meal initiation and remained elevated for the first 14 min of meals. Free fatty acids also increased at 8, 10, 12, 16, and 18 min after meal initiation. There were no consistent changes in packed cell volume, glucose, beta-hydroxybutyrate, or volatile fatty acids during this time. On control days when no feed was consumed, there were no significant changes in concentrations of metabolites or insulin. The increase in insulin of portal blood, which occurs upon meal initiation, preceded changes in metabolites. Therefore, the rapid change in insulin may be the result of a reflex neural stimulation rather than the result of a metabolite stimulating release of insulin.
选用四头经手术安装门静脉采血装置的荷斯坦公牛，研究与自然采食相关的门静脉血液中代谢物和胰岛素的变化。动物在单独的电子控制饲喂单元中饲喂全混合日粮（消化能3.4千卡/克）。在采食前、采食期间和采食后采集血液。采食期间，每隔2分钟采集一次血样。共采集了50次个体采食的血样。平均采食时长为15.0分钟，每餐平均采食量为631.7克。采食开始后2分钟内门静脉胰岛素升高，并在采食的前14分钟内保持升高。游离脂肪酸在采食开始后8、10、12、16和18分钟也升高。在此期间，血细胞比容、葡萄糖、β-羟基丁酸或挥发性脂肪酸没有一致的变化。在不采食的对照日，代谢物或胰岛素浓度没有显著变化。采食开始时门静脉胰岛素的升高先于代谢物的变化。因此，胰岛素的快速变化可能是神经反射刺激的结果，而不是代谢物刺激胰岛素释放的结果。
