In vivo studies of mucosal-serosal transfer in rat jejunum.

In anesthetized rats, the appearance rates of a series of labeled substances in jejunal venous blood (phi B) and serosal bath (phi S) were measured in vivo (intestinal blood flow rate 1.5 ml min-1 g-1) after intraluminal administration of 0.5 ml buffer solution (initial concentration 1 mmol/1 or 1 GBq/1 tritiated water) into a closed jejunal segment (length 4-5 cm). Between 32% (erythritol) and 93% (salicylic acid) of the administered activity (unchanged substance and possible metabolites) appeared in the intestinal venous blood within 60 min. The fraction recovered from the serosal bath after 15 (60) min was 11 (6)% for tritiated water, 7 (4)% for aniline, 3 (7)% for aminopyrine, 5 (4)% for butanol, 3 (3)% for benzyl alcohol, 2 (4)% for benzylamine, 1-2% for benzoic acid, theophylline, methyl-alpha-D -glucopyranoside, L-lysine, antipyrine, and urea, and less than 1% for L-phenylalanine, D-galactose, erythritol, and salicylic acid. During single pass perfusion of a jejunal segment (length 3-4 cm) the fraction of serosal transfer phi S/(phi B + phi S) was 19% for tritiated water, 4.9% for antipyrine, 0.5% for benzoic acid, and 0.08% for salicylic acid. Distension of the intestinal wall by administration of 1 ml buffer solution instead of 0.5 ml increased the appearance rate of benzoic acid and antipyrine in intestinal venous blood by a factor of 2 and serosal transfer by a factor of approximately 3.(ABSTRACT TRUNCATED AT 250 WORDS)