Low-molecular-weight polyethylene glycol as a probe of gastrointestinal permeability after alcohol ingestion

Abstract

Gastrointestinal permeability has been assessed previously by the excretion of PEG-400, which consists of inert molecules that are neither degraded nor metabolized and are excreted intact in the urine. We report here the effects of alcohol on gastrointestinal permeability using PEG-400. Ten grams of PEG-400 dissolved in 60 ml of water were given to 12 intoxicated alcoholics (mean blood alcohol: 2406 mg/liter). The mean urinary excretion of PEG-400 in the following 6 hr was 3.75 +/- 0.3 g SEM. When repeated after sobering up (mean elapsed time: 45 hr), all except one subject showed a decrease in PEG-400 excretion (mean: 2.08 +/- 0.2 g) (P less than 0.001). Similar experiments were conducted in two series with 12 normal controls. (1) In 7 subjects the administration on consecutive days of (a) PEG-400 (10 g) alone, (b) 10.2 g (0.42 mol) of ethanol plus PEG-400 (10 g), (c) PEG-400 (10 g) alone, and (d) PEG-400 (10 g) plus a diuretic (40 mg furosemide) resulted in the following values of PEG-400 excretion in urine: (a) 2.12 +/- 0.3 g; (b) 3.5 +/- 0.3 g, P less than 0.005; (c) 2.02 +/- 0.4, NS; and (d) 2.2 +/- 0.2 g, NS. (2) In the second experiment (5 subjects) the administration on subsequent days of (a) PEG-400 (10 g) + 0.42 mol of urea; (b) PEG-400 (10 g) + 19.2 g ethanol; (c) PEG-400 (10 g) + 0.42 mol of urea resulted also, as in the previous experiment, in increased urinary excretion of PEG-400 after the solution (b) containing ethanol (P less than 0.001). Peak serum levels of PEG-400 were (a) 0.094 +/- 0.01 g/liter; (b) 0.152 +/- 0.02 g/liter (P less than 0.05); and (c) 0.095 +/- 0.01 (P less than 0.05). The ratio of urea--creatinine clearance and urinary volumes were the same in the three periods. Therefore, PEG-400 excretion was not related to changes in urinary clearance or in volume, since the furosemide increased the volume but not PEG-400 excretion. It is concluded that ethanol increases the permeability of the gastrointestinal tract as measured by the PEG-400 test, both in chronic alcoholics during intoxication and in nonalcoholics after a small dose of ethanol. The permeability alteration is transient once ethanol ingestion stops.