Comparison of the intravenous and intraperitoneal routes of administration of tritiated thymidine in studies of cell production in the gastrointestinal tract of the rat

Incorporation of³H-Thymidine into DNA-synthesizing cells of the gastrointestinal tract of the rat was examined following administration of the isotope by intraperitoneal and intravenous routes. Estimates of whole tissue incorporation expressed as DPM/mg dry weight and of proliferating cells expressed as DPM/crypt or gland in the different segments of the gut indicated no differences in the degree of³H-TdR uptake into DNA following intraperitoneal or intravenous routes of administration. The possibility of misdirected I.P. injections was examined following injection of³H-TdR into the cecum or bladder. DPM/mg wet weight of gastrointestinal tissues indicated reduction in the uptake of³H-TdR into DNA of intestinal tissues following intracecal and intrabladder administration of³H-Tdr. The intraperitoneal route of administration of³H-TdR appears to be equally effective in the distribution of the isotope into different segments of the gut when compared to the intravenous route and is a more convenient method in studies of cell production in the gastrointestinal tract of the rat.