d-glucose balance in the enterocyte of rat jejunum “in vitro”

An everted sac of male albino rat jejunum (Wistar strain) incubated in vitro is used. Netd-glucose and Na⁺ transport together withd-glucose concentration in the emerging fluid 5], or in the serosal fluid, and in the enterocytes are determined. Celld-glucose concentration does not change significantly in a range between 20–200 moles or between 50–500 moles of netd-glucose transepithelial transport, depending on the experimental conditions.As far as cellulard-glucose and Na⁺ concentration is concerned, the enterocyte behaves as an homeostatic system.The mechanism involved ind-glucose extrusion is extensively discussed. Two hypotheses seem to be possible. First, the mechanism is an active metabolically dependent one, just as it is for sodium transport. Second, the metabolic activity favoursd-glucose facilitated permeability through the basolateral membrane in such a way as to maintain a constant relationship betweend-glucose and Na-extrusion, notwithstanding the fact thatd-glucose concentration gradient across the basolateral membrane lowers by increasing Na and glucose extrusion rate.