Independent effects of arginine and glucose on ovine fetal insulin secretion

Glucose Suppression of Insulin Secretion in Chronically Hyperglycemic Fetal Sheep

“…The data in the present study confirm the ability of the fetal sheep to secrete insulin in response to arginine, but there was no measurable increase in arginine-stimulated insulin secretion with advancing gestational age over the brief age range studied (122-138 d). The decreased insulin secretion in response to arginine seen in the HG fetuses compared with controls during the third study after at least 2 wk of hyperglycemia was unlikely to be due to lower arginine concentrations obtained in the hyperglycemic fetuses compared with controls as preliminar y data in our laboratory indicate that both groups received doses of arginine that were well above those that produced a maximum effect of arginine on insulin secretion in fetal sheep, regardless of the level of glycemia (12).…”

“…After 120 min, eight of the fetuses received a supplemental 5-min infusion of arginine free base of 0.18-0.20 mmol/kg estimated fetal weight (1.25 g in 9.0 mL of 0.9% saline with 2.0 mL of 2.0 N acetic acid to bring the pH to 8). Based on preliminary trials, this pharmacologic dose of arginine in fetal sheep in late gesta tion produces a maximum response of insulin secretion to arginine (12). The hyperglycemic glucose clamp was continued, and blood samples were collected between 125 and 150 min.…”