Effect of pH and sodium ions on intestinal uptake of lysine in rats
Kaur, S.; Babbar, H.S.; Mahmood, A.
Indian Journal of Experimental Biology 31(6): 529-532
1993
ISSN/ISBN: 0019-5189 PMID: 8406600 Document Number: 411006
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 (V-max), with little change in affinity constant (K-t). Arrhenius analysis revealed a biphasic curve for lysine uptake with transition temperature (T-c) around 20 degree C (24 degree C at pH 5.2 in presence of Na+). The energy of activation (E-a) below (16.1-23.4 Kcal/mole) and above (6.7-8.6 Kcal/mole) the T-c 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.