Regulation of transmural transport of amino acid/metal conjugates by dietary calcium in crustacean digestive tract

摘要: Effects of luminal Ca(2+) and Mn(2+) on transmural mucosal to serosal (MS) transport (3) H-L-leucine were characterized in the isolated perfused intestine American lobster, Homarus americanus. MS presence 20 µM was a sigmoidal function amino acid concentration, following Hill equation for multisite cooperative, carrier-mediated, transport. Luminal non-competitive inhibitor -stimulated flux. Amino hyperbolically stimulated by or Mn(2+). During -stimulation flux, addition 25 mM strongly reduced Jmax , without affecting binding properties. Hyperbolic stimulation flux also inhibited significantly reducing . Increasing concentration verapamil, calcium channel blocker, increased 100 nM diffusional uptake into intestinal epithelial cells through verapamil-sensitive channels. A model is proposed supporting concept molecular mimicry, whereby enters lobster one more acid-specific transporters dipeptide-like transporter that capable transporting peptide mimics (bis-complexes) between using membrane potential as major driving force event. According model, entry apical channels regulates magnitude therefore size bis-complex uptake.