Rheogenic property of Na+/acidic amino acid co-transport by guinea pig intestine.

Abstract

The influx of L-glutamate or L-aspartate across the intestinal brush border membrane was absolutely dependent on the presence of Na+ in the mucosal solution and saturable. The addition of these amino acids into the mucosal solution induced a sudden and sustained increase in the transepithelial potential difference (PD J, which was found to be absolutely dependent on the presence of Na+ in the mucosal solution. The increases in PD t induced by L-glutamate or L-aspartate conformed to Michaelis-Menten kinetics against the concentration of each organic substrate. On the other hand, the relationship between the change in short-circuit current induced by acidic amino acid and Na+ concentration did not conform to Michaelis-Menten kinetics but was sigmoid. A kinetic study indicated that 2 Na+ were translocated per molecule of the acidic amino acid. The PD t was not altered by the total replacement of K+ by Na+ in the mucosal solution and showed the optimum pH at around 7. The transfer of L-glutamate from mucosal to serosal solution was examined with everted sac of ileum. A significant increase in serosal appearance was observed for L-glutamate and Lalanine after the incubation with L-glutamate. The serosal appearance of L-glutamate was unaffected by the presence or absence of HC03-.

Presteady-state kinetics and carrier-mediated transport: A theoretical analysis

“…Figure 6 shows the result of such a simulation with values for zx and zL of + 1 and -1, respectively, so that the loaded complex is neutral. Such a situation was chosen to mimick glutamic acid transport through the binding of 1 glutamate-and 2 Na § ions on a negatively charged carrier (Burckhardt et al, 1980;Schneider & Sacktor, 1980;Nelson et al, 1983;Himukai, 1984;Fukuhara & Turner, 1985;Rajendran et al, 1987;Wingrove & Kimmich, 1987). It can thus be concluded that lag-to-burst transitions can be generated under these conditions when going from insidepositive to inside-negative membrane potentials.…”

The characteristics of carnosine transport and carnosine-induced electrical phenomena by the everted intestine of guinea pig.

“…Experimental arrangements and procedures were identical to those described in the previous papers (HIMUKAI et al, 1983 ;HIMUKAI, 1984). Briefly, short segments, 2-3 cm long, of the ileum were excised from guinea pigs anesthetized with urethan.…”

Everted gut sac model as a tool in pharmaceutical research: limitations and applications

“…Different animals have been chosen for everted gut sac experiments, for example frog, catfish, rat, rabbit, sheep, chicken, goldfish, turtle, pigs, guinea pig and mice [31,32,34–44] . The everted rat intestinal sac is the most commonly used sac for in‐vitro studies.…”