The Effect of Pancreatectomy on the Uptake of Metabolites by the Sheep Fetus

Abstract

SUMMARYThe effects of fetal pancreatectomy on the uptake of oxygen, glucose and lactate by the fetus, uterus and uteroplacental tissues were investigated in chronically catheterized sheep during the last third of gestation. Pancreatectomy reduced the uptake of glucose by the fetus but had little apparent effect on glucose uptake by the uterus or uteroplacental tissues. The mean umbilical uptake of glucose by the pancreatectomized fetuses was 104+ ± 11,mol/kg. min (n = 4) which was significantly less than the value observed in the intact fetuses (24 5 + 2 7 ,tmol/kg. min, n = 4, P < 0 01). When all the data from the pancreatectomized and intact fetuses were combined, there was a significant positive correlation between the plasma insulin concentration in utero and the umbilical uptake of glucose (r= 095, n = 14, P < 0 01). The glucose/oxygen quotient in the pancreatectomized fetuses (0-32+0-02, n=9) was significantly less than the value observed in the intact fetuses (0 59 + 0 04, n = 6, P < 0 01). There was also a significant positive correlation between the glucose/oxygen quotient and the plasma concentration of insulin in the fetus (r=0 73, n=59, P < 001). Pancreatectomy had no significant effect on the fetal lactate/oxygen quotient or on the uptake of oxygen or lactate by any of the tissues. These observations demonstrate that the endogenous concentration of insulin is a physiological regulator of glucose uptake by the fetal tissues.

Blood Chemistry, Nutrient Metabolism, and Organ Weights in Fetal and Newborn Calves Derived from In Vitro-Produced Bovine Embryos1

“…The third major oxidative substrate in fetal calves, amino acids, was not measured in the present study, but these are known to contribute less than glucose and lactate to total substrate oxidation in utero [14,25]. As the umbilical uptake of glucose normally decreases while that of lactate increases towards term [14,17,25,26], our glucose/lactate data indicate that IVP has advanced the normal gestational changes in the nutritional demands of the calf fetus. Alternatively, there may have been changes in the transfer capacity and/or nutrient requirements of the placenta that account for the apparent differences in umbilical uptakes of glucose and lactate between the IVP and AI calves.…”

“…Blood hemoglobin (Hb), oxygen saturation (O 2 sat), and total oxygen content (O 2 ct) were measured by a hemoxymeter (OSM3; Radiometer, Copenhagen, Denmark). Cortisol concentrations in plasma were determined by RIA [17].…”

Chronic pulsatile infusion of growth hormone to growth-restricted fetal sheep increases circulating fetal insulin-like growth factor-I levels but not fetal growth

“…Postnatally, GH treatment is associated with impaired glucose metabolism due to GH-induced insulin resistance (Okuda et al 1994, Johansen et al 1999. In the fetus insulin plays an important part in the regulation of growth (Fowden et al 1989), largely by regulating fetal tissue uptake of glucose and amino acids (Fowden et al 1986, Fowden & Hay 1988. Thus, one could speculate that fetal GH treatment may have caused insulin resistance, which would have prevented blood glucose levels from declining and also prevented any effect of the increased IGF-I levels on fetal growth.…”

Maturation of pancreatic β-cell function in the fetal horse during late gestation

“…Plasma concentrations of glucose were measured using a Yellow Springs analyser (YSI 2300 Stat Plus; Yellow Springs, OH, USA) while plasma -amino-nitrogen levels were measured colorimetrically as described previously (Fowden et al 1986). Plasma concentrations of insulin and cortisol were measured by radioimmunoassay validated for use with equine plasma (Fowden et al 1980, Rossdale et al 1982.…”