Studies of gastrointestinal interactions. I. A mathematical analysis of jejunal indicator concentrations used to calculate jejunal flow and mean transit time.

Abstract

Jejunal flows and intestinal mean transit times in man were calculated after a marked test meal. The procedure involved continuous and successive infusion of three modifications of vitamin B12 into proximal duodenum and measuring the concentrations 65 cm down the jejunum. A simple relation was found between the flow of indicator and change in mean transit time Δtm.tm could be calculated directly from the relation between time and per cent single to total indicator. Flow could be calculated secondarily. Flow could also be calculated directly by means of an iteration procedure and tm secondarily. The methods were tested in a model.