Fasting and postprandial polyamine concentrations in the human digestive lumen

Polyamines are essential to cellular proliferation and differentiation. The gastrointestinal tract could represent a major source of polyamines in the body; however, there is little information regarding the presence of polyamines in the human intestinal chyme, and the source of these intraluminal polyamines remains unclear. The aims of our study were to determine the concentrations and flow rates of polyamines in the human intestinal lumen and to estimate the contribution from food to these concentrations. Polyamine concentrations and flow rates were determined after 12 h of fasting in jejunal (n = 25) and ileal (n = 9) effluents collected by the slow-marker perfusion technique. Kinetic studies were performed after water ingestion (no polyamines) in the jejunum (n = 6) and ileum (n = 5) and in the jejunum after a yogurt test meal (polyamine content: 2.8 mu mol putrescine, 2.1 mu mol cadaverine, 2.1 mu mol spermidine, and 1.9 mu mol spermine; ii = 9). There were significant polyamine concentrations in the lumen of the human gut during the fasting state, suggesting endogenous secretion. Higher polyamine concentrations were observed in the jejunum than in the ileum (P < 0.05), suggesting proximal absorption. Kinetic studies showed a 25% transitory increase in the jejunal putrescine flow rate after ingestion of the yogurt test meal, suggesting that dietary polyamines are fully absorbed.