The involvement of active sodium transport in the rectal absorption of gentamicin sulfate was examined in rats, employing aqueous microenemas of known total ionic strength (p) in the presence or absence of absorption-promoting adjuvants. Rectal gentamicin bioavailability, which is negligible (1 f 1.2%) a t an ionic strength of 0.15 without adjuvants, is significantly ( p < 0.01) increased by including adjuvants in the formulation (sodium salicylate, 12 f 4.0%; sodium-5-bromosalicylate, 59 f 15.1%; disodium ethylene(dinitrilo)tetraacetate, 24 f 9.3%). Pretreating the rectal mucosa cells with ouabain, a specific inhibitor of active sodium transport, significantly ( p < 0.01) reduced gentamicin absorption in response to all three adjuvants. In contrast to previous findings with sodium chloride, high ionic strength choline chloride ( p = 1.056) did not promote gentamicin absorption. The data indicate that active sodium transport is an integral component of rectal absorption of water-soluble compounds and may be involved in the mechanism of action of absorption-promoting adjuvants.
Keyphrases 0 Gentamicin sulfate-rectal absorption, effect of choline chloride and ouabain 0 Choline chloride-effect on rectal absorption of gentamicin sulfate adjuvant enhancement Ouabain-effect on the rectal absorption of gentamicin sulfate Rectal absorption-gentamicin sulfate, effect of choline chloride and ouabain.