Background
The aim was to establish the effect of the osmolality of orally consumed liquids on gastric myoelectrical activity (GMA).
Material and Method
Twenty-five healthy volunteers (13 women, 12 men aged 29.4+/-1.4 [SE] years) underwent five examinations on separate days. After a 20-min basal electrogastrographic recording, the volunteers drank 400 ml of a) bi-distilled water, b) 0.9% NaCl, osmolality 286 mmol/kg, c) 2.9% NaCl, osmolality 827 mmol/kg, d) 5% glucose, osmolality 282 mmol/kg, energy density 209 kcal/l, or e) 15% glucose, osmolality 836 mmol/kg, 627 kcal/l. Then the registration of GMA was continued for 60 min. Gastric emptying was measured with the 13C-acetate breath test.
Results
Compared with distilled water, the isotonic glucose drink elicited a positive chronotropic influence on and stabilization of GMA. At the transition from isotonicity to hypertonicity, a pronounced destabilization of GMA was observed, with opposite directions of changes brought about by the presence or absence of a caloric load; bradygastria was manifested after the energy-free hypertonic NaCl solution whereas hypertonic glucose evoked a tachygastric pattern. A marked delay in gastric emptying was found with both hypertonic drinks.
Conclusions
Osmolality and its interplay with chemical composition/energy density must be taken into account when choosing a test meal for an electrogastrographic examination and interpreting its results. Of the five fluids examined, isotonic glucose appeared to be the drink least disturbing to GMA.

Keywords: Osmolar Concentration, Gastric Emptying, Single-Blind Method, Energy Intake, Stomach - physiology