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Influence of acute food restriction on Ca2+Mg2+ ATPase activity in rabbit skeletal muscle
P.39 INFLUENCE OF ACUTE FOOD RESTRICTION ON Ca2+fMg2+ ATPase ACTIVITY IN RABBIT SKELETAL MUSCLE. S.Wootton & J.McWhirter. Dept of Nutrition & Biochemistry, Southampton University, UK. The impaired contractile characteristics of skeletal muscle reported in malnourishment may be due in part to an altered ability to regulate intracellular calcium. The aim of this study was to examine the influence of acute food restriction on the Ca2+/Mg2+ dependent ATPase of skeletal muscle sarcoplasmic reticulum - the principle mechanism for regulating Cai. Five female NZW rabbits were maintained on their normal stock diet (Labsure CRB) for 7d (C) whilst five food-restricted rabbits (FR) received a quantity of food equal to 25% of the daily intake of their weight-matched littermate control. ATPase activity of SR vesicles prepared from homogenates of white and red hindlimb muscles was determined using a linked enzyme assay in the absence (coupled activity) and presence (uncoupled activity) of Ca ionophore A23187 (McWhirter et al. Biochem J, in press 1987). The body weights of the FR group fell from 3.354 + 0.545kg to 3.116 +_ 0.591kg over the 7d (%+_sd, pc.05) whilst C group remained unchanged 3.324 5 0.767kg to 3.382 + 0.687kg (NS). RESULTS
C-WHITE -RED FR-WHITE -RED
ATPase ACTIVITY (pm01 Pilmg protein; 2 2 sd) COUPLED UNCOUPLED U:C 0.93 + 0.24 11.10 + 1.69 12.88 0.94 r 0.23 9.98 + 1.86 11.06 1.29 + 0.43* 9.60 f. 2.93 8.72 1.11 + 0.46 7.88 2 4.00 7.72 *sig. diff. from C value p < 0.05
RATIO _+ 5.27 +_ 3.19 + 4.57" + 4.08*
As the ratio of ATPase:total protein remained unchanged, the lower uncoupled:coupled ratios would suggest a decreased efficiency of Ca pumping following food restriction. Such changes may in turn modify the contractile properties of skeletal muscle.
p.40
EFFECTS OF TRYPSIN CASEIN HYDROLYSATE (CH), CASEIN WITHOUT PHOSPHOPEPTIDE HYDROLYSATES (CWPPH) AND PHGSPHOPEPTIDES (CPPH) ON PANCREATIC PROTEASE (PP) CONCENTRATIONS IN JEJUNAL LUMEN (J) AFTER AN ACUTE STARVATION IN RATS. M.G. POULLAIN, L. ROGER, J.P. BROYART, J. MACRY, J.P. CEZARD - INSERM U.120 Le Vesinet, SOPHARGA R.U. France. As it has been previously shown, after an acute starvation (72h), CPPH diet determined a more rapid and higher jejunal mucosal growth as compare to CWPPH, and CWPPH showed a statistically higher N-aminopeptidase (N.A.) activity and an earlier sucrase (S) activity increase (maximum activity was reached at 24h for CWPPH, 72h for CPPH, intermediate time with CH). These results could be consequences of changes in pancreatic protease secretions induced by the three diets, as it is known that PP are implicated in mucosal trophicity of the jejunum (J) and in microvillus membrane enzyme turn-over (such as S and N.A.). To confirm this hypothesis we determined the activity of trypsin (T), chymotrypsin (CT) and elastase (E), in the lumen of the upper jejunum, in 64 rats after 72h of starvation and 24 and 72h of refeeding (R) with CH, CWPPH and CPPH diets and in 18 controls rats (fed 96h without fast). Each diet had the same nitrogen, caloric, vitamin and mineral content. The amino acid compositionfulfilthe needs of growing rats. Results show no statistical difference of trypsin and elastase concentrations in the lumen of J in controls and during refeeding (24 and 72h). In contrast a drastic decrease (p
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C-WHITE -RED FR-WHITE -RED
ATPase ACTIVITY (pm01 Pilmg protein; 2 2 sd) COUPLED UNCOUPLED U:C 0.93 + 0.24 11.10 + 1.69 12.88 0.94 r 0.23 9.98 + 1.86 11.06 1.29 + 0.43* 9.60 f. 2.93 8.72 1.11 + 0.46 7.88 2 4.00 7.72 *sig. diff. from C value p < 0.05
RATIO _+ 5.27 +_ 3.19 + 4.57" + 4.08*
As the ratio of ATPase:total protein remained unchanged, the lower uncoupled:coupled ratios would suggest a decreased efficiency of Ca pumping following food restriction. Such changes may in turn modify the contractile properties of skeletal muscle.
p.40
EFFECTS OF TRYPSIN CASEIN HYDROLYSATE (CH), CASEIN WITHOUT PHOSPHOPEPTIDE HYDROLYSATES (CWPPH) AND PHGSPHOPEPTIDES (CPPH) ON PANCREATIC PROTEASE (PP) CONCENTRATIONS IN JEJUNAL LUMEN (J) AFTER AN ACUTE STARVATION IN RATS. M.G. POULLAIN, L. ROGER, J.P. BROYART, J. MACRY, J.P. CEZARD - INSERM U.120 Le Vesinet, SOPHARGA R.U. France. As it has been previously shown, after an acute starvation (72h), CPPH diet determined a more rapid and higher jejunal mucosal growth as compare to CWPPH, and CWPPH showed a statistically higher N-aminopeptidase (N.A.) activity and an earlier sucrase (S) activity increase (maximum activity was reached at 24h for CWPPH, 72h for CPPH, intermediate time with CH). These results could be consequences of changes in pancreatic protease secretions induced by the three diets, as it is known that PP are implicated in mucosal trophicity of the jejunum (J) and in microvillus membrane enzyme turn-over (such as S and N.A.). To confirm this hypothesis we determined the activity of trypsin (T), chymotrypsin (CT) and elastase (E), in the lumen of the upper jejunum, in 64 rats after 72h of starvation and 24 and 72h of refeeding (R) with CH, CWPPH and CPPH diets and in 18 controls rats (fed 96h without fast). Each diet had the same nitrogen, caloric, vitamin and mineral content. The amino acid compositionfulfilthe needs of growing rats. Results show no statistical difference of trypsin and elastase concentrations in the lumen of J in controls and during refeeding (24 and 72h). In contrast a drastic decrease (p
74