DIETS CAUSING TAURINE DEPLETION IN CATS SUBSTANTIALLY ELEVATE POSTPRANDIAL PLASMA CHOLECYSTOKININ CONCENTRATION

Excessive secretion of the intestinal hormone cholecystokinin (CCK) wa s postulated to cause diet-related taurine depletion in cats, To test this hypothesis, plasma CCK-like immunoreactivity (CCK-LI) was measure d in cats given four diets, two purified and two canned, that containe d similar concentrations of protein, fat, moisture and taurine but pro duced variable rates of taurine depletion. Plasma CCK-LI was measured by RIA with a tyrosine-sulfate specific, C-terminal antiserum, validat ed for use in cat plasma, As indicated by measurements of taurine in w hole blood and urine, a purified diet containing casein maintained bod y taurine, whereas the same diet containing soybean protein and a comm ercial canned diet preserved either by freezing or cooking depleted bo dy taurine. Preprandial and peak postprandial plasma CCK-LI in cats gi ven the casein-containing diet were 10.6 +/- 1.4 and 27.6 +/- 4.8 pmol /L, respectively, similar to two- to tenfold greater than those report ed in humans. Integrated postprandial plasma CCK-LI was less for cats given the casein diet than cats given both forms of the canned diet; i t tended to be lower in cats given the casein diet than in cats given the soy protein diet. A negative linear correlation was observed betwe en apparent nitrogen digestibilities of the diets and integrated plasm a CCK-LI. The results indicated that diets that cause taurine depletio n have lower protein digestibilities and cause greater endocrine secre tion of CCK than diets that maintain body taurine status.