Effect of 4-hour hyperglycaemia and hyperinsulinaemia on plasma atrial natriuretic factor concentrations

To elucidate the mechanism behind the increased plasma atrial natriuretic factor (ANF) reported in Type 1 diabetic patients with glomerular hyperfiltration and incipient nephropathy, we studied the effects of a short-term moderate hyperglycemia with concomitant hyperinsulinaemia on plasma ANF concentrations and glomerular filtration rate (GFR) in healthy male volunteers. Following a 2-hour basal run-in period, blood glucose level was clamped at 12.2 mmol/l for 4 hours by infusing 20% glucose solution (hyperglycaemia study) or the level was kept normal by infusing isotonic saline over the 4 hours (saline control study). Plasma ANF increased slightly both in the hyperglycaemia phase (from 25.7 +/- 6.3 to 32.1 +/- 7.5 ng/l at 3 hours [p < 0.02] and 31.0 +/- 6.6 ng/l at 4 hours [p = 0.058, mean +/- SD]) and in the control phase (from 17.7 +/- 6.1 to 26.1 +/- 13.5 ng/l at 3 hours [p < 0.05] and 25.4 +/- 11.7 ng/l at 4 hours [p < 0.05]) as compared with the respective baseline values. GFR remained unchanged both in the hyperglycaemia (from 108 +/- 8 to 104 +/- 13 ml/min/1.73 m2) and the saline control phases (from 106 +/- 7 to 101 +/- 7 ml/min/1.73 m2), respectively. The results of this short-term study showed no association between the moderate hyperglycaemia with a concomitant hyperinsulinaemia and plasma ANF concentration in non-diabetic normotensive subjects.