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3H‐D‐glucose transport is both Na + ‐ and K + ‐dependent in the marine shrimp, Litopenaeus setiferus
Author(s) -
Ahearn Gregory A.,
Obi Ijeoma,
Sterling Kennth M.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1111.4
Subject(s) - shrimp , chemistry , sugar , sodium , brush border , zoology , membrane , biophysics , biochemistry , vesicle , biology , fishery , organic chemistry
This study reports the occurrence of a brush border 3 H‐D‐glucose transporter in the digestive tract of a marine shrimp that is similarly stimulated by both Na + and K + . Hepatopancreatic brush border membrane vesicles loaded with 300 mM mannitol exhibited 0.1 mM 3 H‐glucose uptake overshoots, that were membrane‐potential‐ sensitive, when incubated in media containing either 150 mM NaCl or KCl. Sugar influxes (15 sec uptakes) in both NaCl or KCl were significantly (p < 0.05) inhibited by 5 mM phloridzin. 3 H‐glucose (0.1 mM) influxes in media containing concentrations of NaCl or KCl from 0 to 400 mM were hyperbolic functions of the salt concentrations with both Km‐ and Jmax –values generally higher for KCl than for NaCl. Significant increases (p < 0.05) in Km‐ and Jmax‐values occurred in both media in the presence of a membrane potential difference (inside negative). 3 H‐glucose influx was a hyperbolic function of [glucose] from 0.1 to 5.0 mM in the presence of either 150 mM NaCl or KCl. Influx kinetic constants (Km and Jmax) were higher in NaCl than in KCl, and imposed inside‐negative membrane potentials decreased the kinetic constants in both instances. Results suggest that sugar absorption in shrimp may be largely K + ‐dependent during juvenile herbivory and Na + ‐dependent in adult omnivory/carnivory. Supported by USDA agriculture and food initiative competitive grant no. 2010‐65206‐20617.