title: Effect of pH and sodium ions on intestinal uptake of lysine in rats.
abstract: Intestinal uptake of lysine in rats progressively decreased with an increase in pH from 5.2 to 8.5, both in the presence and absence of Na+ ions. At pH 5.2 lysine uptake was 30-35% more than that at neutral pH. Na+ activated lysine uptake by 40-50% at pH 5.2 and it was increased to 110-120% at neutral pH. The observed increase in lysine uptake in response to Na+ and H+ gradients was due to enhanced maximal velocity (Vmax), with little change in affinity constant (Kt). Arrhenius analysis revealed a biphasic curve for lysine uptake with transition temperature (Tc) around 20 degrees C (24 degrees C at pH 5.2 in presence of Na+). The energy of activation (Ea) below (16.1-23.4 Kcal/mole) and above (6.7-8.6 Kcal/mole) the Tc was similar at pH 5.2 and 7.0 both in the presence and absence of Na+ ions. The sensitivity of lysine uptake to various inhibitors was also dependent upon pH and Na+ ions.
authors.affiliation: Department of Biochemistry, Panjab University, Chandigarh, India.
authors.forename: S
authors.initials: S
authors.lastname: Kaur
authors.forename: H S
authors.initials: HS
authors.lastname: Babbar
authors.forename: A
authors.initials: A
authors.lastname: Mahmood
mesh_terms: D000818:Animals; D018053:Arsenites / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D006246:Harmaline / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption / Q000187:drug effects*; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D007510:Isatin / Q000494:pharmacology; D008239:Lysine / Q000493:pharmacokinetics*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000494:pharmacology*; D017670:Sodium Compounds / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism
chemical_list: D018053:Arsenites; D004140:Dinitrophenols; D007461:Iodoacetates; D017670:Sodium Compounds; D017923:Sodium-Hydrogen Exchangers; C017947:sodium arsenite; C067109:2,3-dinitrophenol; D007510:Isatin; D012964:Sodium; D006246:Harmaline; D008239:Lysine; D005033:Ethylmaleimide; D019807:Iodoacetic Acid