Glucose Metabolism and Insulin Action in Sheep Exposed to Cold

用[U-^C]葡萄糖进行同位素稀释，结合测量后躯动静脉差和血流量，以检查冷暴露对绵羊全身和后躯净葡萄糖代谢的影响。<13>测定在热中性环境中进行，并在第5天的轻度冷暴露。在热中性环境和冷暴露期间，全身血糖周转率分别为1.56和1.91 mg kg ^min ^。<-1><-1>净后躯葡萄糖摄取量分别为0.79和1.19 mg/kg·min·min·min·min-1，分别相当于全身转换率的50%和61%。<-1><-1>这些结果表明，冷暴露期间，尽管全身血糖周转率没有显著增加，但绵羊后躯对葡萄糖摄取的贡献有增加的趋势。冷暴露和采食量水平对血糖动力学、血浆胰岛素和胰高血糖素对摄食的反应以及组织反应性和敏感性的影响。 ...更多信息 在绵羊中测量胰岛素的活性。同位素稀释技术用于测定血糖转换率，高胰岛素正葡萄糖钳夹技术用于测定胰岛素作用和敏感性。血浆胰岛素和胰高血糖素对摄食的反应主要受饲料水平和环境温度的影响。血糖周转率在冷暴露比在热中性环境中更大，往往是更大的羊饲料随意。随着饲养时间的延长，各指标变化不大。高胰岛素正葡萄糖钳夹技术在热中性环境中和冷暴露第8天进行。葡萄糖输注率（GIR）是更大的冷暴露比在热中性环境中，并限制喂养比随意喂养。最大GIR在冷暴露期间也较大，但不受饮食水平的影响。血浆胰岛素浓度在半最大GIR往往是较低的冷暴露比在热中性环境中，饮食之间没有差异。因此，胰岛素作用敏感性受冷暴露的影响，但不能得到证据表明，它们受到影响的饲料采食量水平饲喂粗饲料的绵羊。少

Isotope dilution using [U-^<13>C] glucose was combined with measurement of hindquarters arteriovenous difference and blood flow to examine the effect of cold exposure on whole-body and net hindquarters glucose metabolism in sheep. Determinations were carried out in a thermoneutral environment and on day 5 of mild cold exposure. Whole-body blood glucose turnover rate was 1.56 and 1.91 mg kg^<-1> min^<-1> in the thermoneutral environment and during cold exposure, respectively. Net hindquarters glucose uptake was 0.79 and 1.19 mg kg^<-1> min^<-1>, corresponding to 50 and 61% of whole-body turnover rate, respectively. These results suggest that in sheep the contribution of glucose uptake by the hindquarters tended to increase during cold exposure, even though whole-body blood glucose turnover rate did not increase significantly.Effects of cold exposure and level of feed intake on blood glucose kinetics, plasma insulin and glucagon responses to feeding and tissue responsiveness and sensitiv … More ity to insulin were measured in sheep. The isotope dilution technique was used for determination of blood glucose turnover rates, and the hyperinsulinemic euglycemic clamp technique was applied for determination of insulin action and sensitivity. Plasma insulin and glucagon responses to feeding were mainly influenced by dietary level and environmental temperature, respectively. Blood glucose turnover rates were greater during cold exposure than in the thermoneutral environment, and tended to be greater for the sheep fed the diet ad libitum. The rates changed little accompanied by feeding. The hyperinsulinemic euglycemic clamp technique was carried out in the thermoneutral environment and on day 8 of cold exposure. The glucose infusion rate (GIR) was greater during cold exposure than in the thermoneutral environment, and were greater for restricted feeding than for ad libitum feeding. The maxmal GIR was also greater during cold exposure, whereas was not influenced by dietary level. Plasma insulin concentrations at the half maxmal GIR tended to be lower during cold exposure than in the thermoneutral environment, and did not differ between diets. Therefore, insulin action sensitivity were influenced by cold exposure, whereas it could not be obtained the evidence that they were influenced by level of feed intake in sheep fed roughage diet. Less