Twenty-one VLBW infants(~rou~ 1)were fed their own mothers milk. Randomly selected similar VLBW infants were fed a standard 24 cal/oz formula(Group 11, 19 pts)and a whey protein based 24 cal/oz formula(Group 111, 20 pts) .Birth weights (gm) and GA (wk) were 1230 + 200, 30.6 + 2.1; 1275 + 222, 31.1 + 1.7 B 1357 + 170, 31.3 2 1.77. respectiveiy .~eedin~s ,-of equal voiume per kg of body weight, were started at 4.9 5 2.5, 5.4 2 4.3 and 5.9 2 4.5 day of life. Total serum protein, albumin, Ca, P, BUN and pH in each group were in normal physiologic range before, during and after the study period of achieving 1800 gm body weight and not different between the gronps. Days of feedings to regain birth weight was statistically different only between I and 11(18.5 We have investigated the mechanism by which colchicine reduces disaccharidase activities in intestinal mucosa. Male CDF strain rats were injected with colchicine (0.5mg/kg body weight) freshly dissolved in physiological saline. Two hours after colchicine injection, each animal was injected with 200 vCi of 3~-leucine. Two hours later, animals were sacrificed, and homogenates and brush borders were prepared from mucosal scrapings. Aliquots were precipitated with TCA and counted for label incorporation into total protein. Sucrase was immunoprecipitated from solubilized brush borders at the experimentally determined equivalence point for each sample, using specific rabbit anti-sucrase antibody. Results (+EM) showed significant reductions of radiolabelling of brush border protein and immunoprecipitated sucrase,but not of total homogenate protein, and brush border sucrase activity was not significantly reduced:control (6) colchicine ( Because in infant rats the intestine is more permeable to Ca than in adults, the infant may be predisposed to hypocalcemia.In suckling (S, 14-15 day old) and adolescent (A, 8 week old) rats we measured net secretion of Ca into the lumen during in situ perfusion of the upper (J) and lower (11) half of the small intestine with a Ca-free solution containingfl: 120 mM NaC1, 5 mM KC1, 25 mM NaHC03, and 30 mg of phenol red. Serum Ca was measured before and at the end of the 2 hr perfusion period. The perfusion solution was recirculated through the segments at a rate of 1 ml/min from reservoirs containing 7 or 25 ml of the perfusion solution, respectively, for the S and A rats. As expected, calcium was secreted into the lumen in all rats. Total net Ca secreted (poles/,2 hrs) was about the same in S and A rats (meanfS.E., S: J 3.9t0.5, I1 4.7t0.5; A: J 3.3f0.5, I1 4.9t1.1) .However, normalized for differences in size of the segments, net secretion rates (poles/hr/g wet wt) were much greater in S than A rats (S: J 8.8t0.9, I1 8.520.6; A:J 1.1f0.1, I1 1.4f0.3).Assuming a serum volume of 5% body weight, Ca loss during perfusion, as % of total serum Ca, was 30% in A and 150% in the S rats. At the end of the perfusion serum Ca (~moles/100 dl) was reduced in S rats only (p<0.05), but was not in the hypocalcemic range (S: 2.0t0.1; A: 2.2f0.3).Thu...