Transport of galactose and sodium across lizard duodenum.
Electrical parameters and transepithelial Na+ and galactose transport were determined in vitro across isolated duodenum of Lacerta galloti lizard. Electrical potential difference (PD) and short-circuit current (Isc) were dependent on the presence of Na+ in the bathing solutions. PD and Isc were affected by addition of galactose to the mucosal solution. Isotopic flux of Na+ measurements across short-circuited duodenum showed a net active Na+ absorption. The net flux of Na+ (JNa+net) accounted for the observed Isc. Both (JNa+net) and Isc were increased by the addition of galactose 5 mM to the mucosal solution. Isotopic flux galactose measurements in open-circuit conditions showed a net active galactose absorption. The net transport of galactose was decreased to zero in the absence of Na+ in mucosal and serosal reservoirs. Galactose has been used to induce changes in short-circuit current (delta Isc) across intestine. delta Isc was a hyperbolic function of galactose concentration characterized by the parameters Vmax (maximum change in delta Isc) and Km (concentration needed to attain a velocity equal to half the Vmax).
D000818:Animals; D001692:Biological Transport; D001693:Biological Transport, Active; D004386:Duodenum / Q000502:physiology*; D004553:Electric Conductivity; D004848:Epithelium / Q000502:physiology; D005690:Galactose / Q000378:metabolism*; D008116:Lizards; D008564:Membrane Potentials / Q000187:drug effects; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology
D012964:Sodium; D005690:Galactose