Effects of adrenaline and amino acids on the release of insulin in the sheep fetus.

The effects of adrenaline and amino acids on beta-cell function have been investigated in chronically catheterized fetal sheep. Infusion of adrenaline (1 microgram/min) abolished the normal beta-cell response to both glucose and arginine. The adrenaline infusion also caused hyperglycaemia and a reduction in the basal plasma insulin concentration in the fetus in the period before the infusion of glucose or arginine was given. Infusion of amino acids increased the speed and the magnitude of the beta-cell response to glucose. The maximum increment in the fetal insulin level in response to glucose was 68.5 +/- 13.5 (S.E.M.) mu u./ml (n = 5) during amino acid infusion which was significantly greater than the value of 16.1 +/- 3.4 mu u./ml observed in the control experiments. The observations are discussed in relation to the regulation of insulin release in utero.