Insulin resistance occurs during various stages of the estrus cycle in dogs. To quantify the effects of proestrus–estrus (PE) and determine whether PE affects liver insulin sensitivity, 11 female mongrel dogs were implanted with sampling and intraportal infusion catheters. Five of the dogs (PE group) entered proestrus after surgery; those remaining in anestrus were controls. The dogs were fasted overnight, [3-3H]glucose and somatostatin were infused through peripheral veins, and glucagon was infused intraportally. Insulin was infused intraportally, with the rate adjusted to maintain arterial plasma glucose at basal levels (PE, 294 ± 25 µU/kg/min; control, 223 ± 21 µU/kg/min). Subsequently the insulin infusion rate was increased by 0.2 mU/kg/min for 120 min (P1) and then to 1.5 mU/kg/min for the last 120 min (P2); glucose was infused peripherally as needed to maintain euglycemia. Insulin concentrations did not differ between groups at any time; they increased 3 µU/mL over baseline during P1 and to 3 times baseline during P2. The glucose infusion rate in PE dogs during P2 was 63% of that in control dogs. Net hepatic glucose output and the endogenous glucose production rate declined 40% to 50% from baseline in both groups during P1; during P2, both groups exhibited a low rate of net hepatic glucose uptake with full suppression of endogenous glucose production. The glucose disappearance rate during P1 and P2 was 35% greater in control than PE dogs. Therefore, PE in canines is associated with loss of nonhepatic (primarily muscle) but not hepatic insulin sensitivity.
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机译:在狗的发情周期的各个阶段都会出现胰岛素抵抗。为了量化发情前期(PE)的影响并确定PE是否会影响肝脏对胰岛素的敏感性,将11只雌性杂种犬植入了采样和门静脉输液导管。手术后有5只狗(PE组)进入了发情期。剩余在发情期的是对照。将狗禁食过夜,通过外周静脉注入[3- 3 sup> H]葡萄糖和生长抑素,并经门静脉内注入胰高血糖素。经门静脉输注胰岛素,并调整速率以将动脉血浆葡萄糖维持在基础水平(PE,294±25 µU / kg / min;对照,223±21 µU / kg / min)。随后,胰岛素输注速率以0.2 mU / kg / min的速度增加120分钟(P1),然后在最后120分钟以1.5 mU / kg / min的速度增加(P2);根据需要向外周注入葡萄糖以维持血糖正常。两组之间的胰岛素浓度在任何时候都没有差异。它们在P1期间比基线增加3 µU / mL,在P2期间增加到基线的3倍。 P2期间PE犬的葡萄糖输注率为对照组的63%。在P1期间,两组的净肝葡萄糖输出量和内源性葡萄糖产生率均比基线下降了40%至50%。在P2期间,两组均表现出较低的净肝葡萄糖摄取率,并且完全抑制了内源性葡萄糖生成。对照中P1和P2期间的葡萄糖消失率比PE狗高35%。因此,犬的PE与非肝(主要是肌肉)的丢失有关,但与肝胰岛素敏感性无关。
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