Haemodynamic and hormonal effects of two different oral glucose loads in normal human subjects.

Abstract

Systemic and regional haemodynamics and hormonal responses to two isovolaemic, iso-osmotic solutions of 0.5 and 1.0 g/kg of glucose were compared in ten normal young subjects (mean age 24 +/- 3 years). Measurements were made while subjects were supine before glucose and every 15 min for 60 min after ingestion of each solution. Superior mesenteric artery (SMA) blood flow rose similarly after each dose. There were corresponding reductions in SMA vascular resistance after each dose but no difference between doses. Pulsatility index of the SMA was lower after 1.0 g/kg. There was no change in blood pressure, heart rate, cardiac index or forearm muscle blood flow after either dose. Plasma glucose levels rose after each dose and were higher after 1.0 g/kg. There was no difference in the plasma insulin rise between doses. Plasma levels of noradrenaline and adrenaline did not change after either dose. These results suggest that with glucose loads within the ranges we used, changes in SMA blood flow are not dose-related and larger increases in SMA blood flow or in plasma insulin than we observed are needed to reflexly activate cardiac output and raise plasma noradrenaline levels in young normal subjects.