High dietary protein and taurine increase cysteine desulfhydration in kittens

The objective of this study was to determine the effect of dietary protein and taurine on cysteine desulfhydration in various kitten tissues. Cysteine desulfhydration was assessed in liver, kidney, skeletal muscle, heart, spl een, brain and jejunum of kittens fed one of the following diets for 5 wk: 20% protein, 0% taurine diet (LPOT); 20% protein, 0.15% taurine diet (LPNT) ; 60% protein, 0% taurine diet (HPOT); and 60% protein, 0.15% taurine diet (HPNT). Cats fed LPOT and HPOT had been fed a taurine-free diet for 10 wk b efore the 5-wk experiment. The activity of cysteine desulfhydration was det ermined by measuring the production of (H2S)-S-35 from S-35-Cysteine in the presence and absence of a-ketoglutarate (alpha KG) in the incubation mediu m. Liver and kidney had the highest total activities among the tissues test ed (P < 0.01). Total hepatic desulfhydration activities [mu mol H2S/(min . kg body wt)] in cats fed LPOT, LPNT, HPOT and HPNT were (mean +/- SEM) 117 +/- 6, 135 +/- 10, 137 +/- 10 and 190 +/- 9, respectively. Dietary taurine had a significant effect on activity when expressed per gram liver(P < 0.01 ), per gram protein (P < 0.05) and per kilogram body weight (P < 0.001). Di etary protein had a significant effect (P < 0.001) only when activity was e xpressed relative to body weight because of the significant effect of prote in on relative liver weight. The direct pathway via cysteine desulfhydrase appears to be the major route of cysteine desulfhydration in kitten liver b ecause the values obtained in the absence of alpha KG were 81-88% of those obtained in the presence of alpha KG.