Evidence for the existence of the Magenstrasse and the Darmstrasse when ingesting a caloric solution after a solid meal: A MRI study

Magnetic resonance imaging was used to investigate gastric emptying and small-intestinal distribution of a manganese-labeled 10.6% glucose solution in a randomized crossover study in 12 healthy volunteers under fasted and postprandial conditions after ingestion of a solid light meal. Following the ingestion of 240 mL of the test solution (100 kcal), manganese contrast appeared rapidly in the small intestine and reached distal regions within approximately 20 min in 9 out of 12 subjects, irrespective of the prandial state. Contacted small-intestinal length and small-intestinal distribution increased continuously during the early phase and plateaued thereafter, closely paralleling gastric emptying of the solution. While absolute intestinal contact lengths were lower under postprandial conditions, normalized spreading showed comparable temporal profiles in fasted and fed states, indicating similar distribution mechanisms. Although distribution was slower than previously reported for water, the spatial extent of intestinal spreading was largely preserved in the caloric vehicle. These findings demonstrate that the Magenstrasse and Darmstrasse are not restricted to non-caloric liquids but also govern the rapid luminal distribution of substances dissolved in caloric solutions, largely independent of prandial state, with relevant implications for oral drug delivery and food-effect interpretation.