Abstract
It is well known that actinomycin D, an inhibitor of DNA directed RNA synthesis, alters enzyme activity. Because of similarities in the kinetics of enzymatic reactions and of active intestinal transport, the effect of actinomycin D on the latter was investigated. Observations were made of the active transport of amino acids (L-leucine and cycloleucine), sugar (3-0-methyl-D-glucose) and inorganic sulfate in the small intestine of the rat utilizing the everted gut sac technique of WILSON and WISEMAN. Transport by intestinal segments obtained from actinomycin D treated animals (single injection of 66 μg/100 gms subcut.) was compared with transport by intestinal segments obtained from matched controls. Studies were carried out at time intervals ranging from 1 to 48 h following injection. No significant effect of actinomycin D on transport was noted before 24h. However, active transport of each of the substances studied was markedly increased (2 to 4 fold increase in concentration gradients) in the animals who received actinomycin D 36 to 48 hours previously.
Although commonly used to inhibit enzyme activity, actinomycin D has been shown to induce several enzymes in rat liver 24 to 48 hours after the administration of a single dose (ROSEN: Science 146–661 [1964]). This delayed effect is similar to that observed in our study of intestinal transport and suggests a possible relationship between the two. The mechanism by which actinomycin D stimulates intestinal transport is unknown although it possibly acts by inhibiting a substance that normally limits the rate of transport. (SPR)
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Anast, C., Adamson, L. & Folwell, J. 80 Stimulation of Active Intestinal Transport by Actinomycin D. Pediatr Res 1, 220–221 (1967). https://doi.org/10.1203/00006450-196705000-00087
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DOI: https://doi.org/10.1203/00006450-196705000-00087