PROSTAGLANDIN-E2 AFFECTS BOTH INSULIN-SECRETION AND PERIPHERAL INSULIN SENSITIVITY

The effect of prostaglandin E2 (PGE2) on plasma C-peptide (CP) level and peripheral insulin effectiveness was studied in twenty-five healthy volunteers. Plasma CP levels were studied in 14 volunteers (group C) during a three-hours PGE2 infusion. The same experiment was repeated a week later, with saline infusion. Plasma CP level were measured 15 minutes before the infusion, at the beginning of the experiment (0 min) as well as 15, 30, 60, 120 and 180 minutes after the start of the infusion. Peripheral insulin sensitivity was studied in vivo by means of the artificial endocrine pancreas (Biostator), using the euglycaemic hyperinsulinaemic clamp technique. The healthy volunteers underwent a three-hour experiment with saline (group A) or with saline and PGE2-10-mu-g/min during the third hour of clamping (group B). There was a significant decrease in plasma CP level at the 15 th and 30 th minute of PGE2 infusion in the subjects from group C (p < 0.05). In the group A there was an increase of 14.2% in the amount of glucose infused during the third hour of clamping as compared to the second (2nd-9.673 +/- 1.680 mg/kg/min, 3rd-11.051 +/- 1.802 mg/kg/min). The amount of glucose infused in the subjects of group B remained the same in the course of clamping (2nd hour-7.938 +/- 2.180 mg/kg/min, 3rd hour-7.932 +/- 2.284 mg/kg/min). The difference in the dynamic changes of the amount of glucose infused between the two groups of volunteers (group A and group B) was significant (F = 5.68, p < 0.01). We observed an increase of 16.1 % in the receptor affinity of the controls from group A during the third hour of clamping as compared to the second (2nd-2.36 +/- 1.15 10(9)M-1, 3rd-2.74 +/- 1.01.10(9)M-1). In the subjects from group B the receptor affinity decreased by 18.3 % during the third hour of clamping (2nd-2.35 +/- 0.3, 3rd-1.92 +/- 0.72.10(9)M-1). The difference in the dynamic alterations of the receptor affinity between the two groups was significant (p < 0.02). The intimate mechanism of this effect of PGE2 remains unknown.