Mechanisms by which dietary protein stimulate secretion of endocrine CCK appear to vary among species. Plasma CCK concentration in cats, like that in humans, but unlike that in rats, is elevated by alimentary mixtures of ammo acids. We have recently investigated the effectiveness of phenylalanine in elevating the plasma CCK concentration of cats. Eight cats were given 10 ml/kg oral-gastric infusions of either 13.5 mM NaCI or 27 mM phenylalanine. The dose of infused phenylalanine, 44 mg/kg, was equivalent to the amount of phenylalanine that would be received in casein given at 1 g/kg. Plasma CCK concentrations, as determined by RIA, were measured before and at 5, 10, 15, 20, and 30 min after infusions. Phenylalanine and saline elevated (P<0.05) CCK concentration, but the response was greater and more prolonged for phenylalanine than for saline. In 8 other cats, the elevation of plasma CCK concentration 15 min after phenylalanine infusion was found to increase linearly (r=0.74, PO.001) when concentrations ranging from 0 to 107 mM were given. Time-integrated CCK responses to infusions of 44 mg/kg phenylalanine were 30% that of 1 g/kg casein infusions and 36% that of 1 g/kg infusions of an amino acid mixture approximating the residue composition of casein. The results indicate that the effect of saline on CCK secretion results from gastric distension and that of protein is mediated, in part, by phenylalanine released during digestion of protein.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology