[Effect of vitamin D on lead assimilation]. / Vliianie vitamina D na usvoenie svintsa.

It was established in experiments on rickety chickens given and not given an additive of 0.5% lead acetate to the diet and vitamin D3 (10 IU/day intramuscularly) for a week that vitamin D induced an appreciable increase of lead deposition in the tissues. The degree of lead poisoning assessed according to the content of delta-aminolevulinic acid in red cells was 8 times as increased as compared with the same indicator in chickens not injected with vitamin D. The balance studies demonstrated that retention of the diet lead under the effect of vitamin D rose 2 times. Vitamin D noticeably stimulated 210Pb absorption from chicken duodenum in experiments in situ.

[Relations between the supply of vitamin D and accumulation of Pb in chickens]. / Otlozhenie Pb v organizme tsypliat v zavisimosti ot obespechennosti vitaminom D.

Lead accumulation in the body of 25-day-old chickens was studied depending on the dose of lead and the presence of vitamin D in the diet. It was found that with the increase of the dose of lead (40, 100 and 200 mg/kg feed), its level in the blood, bones, kidneys and liver grows. Introduction of vitamin D in the diet (500 IU per kg) considerably raises the content of lead in the blood (from 212 to 284 micrograms/100 ml) in bone tissues (from 29.4 to 242.7 mg per g dry substance). Single injection of vitamin D to rachitic chickens also promotes lead accumulation in the tissues. Thus a conclusion may be drawn that vitamin D stimulates lead accumulation.

[Direct stimulatory action of blood serum, vitamin D3, and its hydroxy-analogs on calcium transport in the small intestine of chicks in vitro]. / Priamoe stimuliruiushchee deistvie syvorotki krovi, vitamina D3 i ego oksi-analogov an transport kal'tsiia v tonkoi kishke tsypliat in vitro.

A study was made of the effect of blood serum, vitamin D3 and its hydroxy-analogs (25-hydroxyvitamin D4. 1 alpha-hydroxyvitamin D3) on Ca2+ transport across the wall of the noninverted small sac of D-avitaminosis chicken during incubation in vitro. It was shown that blood serum from chickens fed vitamin D3 in different doses (50--20 000 IU) and at varying time (1--72 h) before sacrifice produced a marked stimulating action on the cation transport 10 min after administration into the intestinal cavity as compared with the effect produced by the serum from D-avitaminosis chickens. Administration into the intestine of vitamin D3 or its hydroxy-analogs in physiological doses (6.25--25.0 ng) also significantly stimulated Ca+ transport over 10 min of incubation.

[Rapid biological method for assessing D-vitamin supply of chicks]. / Biologicheskii ekspress-metod otsenki D-vitaminnoi obespechennosti tyspliat.

A segment of the small intestine of chicks turned inside out and pulled on a glass rod was placed into a buffer solution. The Ca2+ consumption from the solution was monitored, using the color murexide reaction. The Ca2+ binding during the first 5 min was much higher in the chicks well supplied with D-vitamin than in the D-vitamin deficient chicks. The level of binding was determined by the content of specific calcium-binding protein in the intestinal mucosa. A close correlation between the dosage of D3-vitamin and the amount of Ca2+ consumed by the intestine from the solution and bound with the mucosa was established. These findings together with the simplicity of the procedure suggest that measurement of the calcium binding capacity of an intestinal segment can be used as a rapid method of assaying the D-vitamin status of the animal.