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Depletion of Calcium, Phosphate, and Strontium From Anesthetized Calves by Hemodialysis^1,2,

Agricultural Research Laboratory of the University of Tennessee⁶, Oak Ridge and Department of Dairy Science, University of Maryland, College Park

ABSTRACT

Two randomized 3 x 3 complete block design experiments were conducted simultaneously to investigate the effects of acute depletion of Ca, P0₄ and Sr by hemodialysis from 90-kg, 100-day-old calves. In one experiment the calves were intravenously dosed with 3 mc each of Ca⁴⁵, P³²O₄, and Sr⁸⁹ at 48-, 96- or 144-hr predialysis. In the other experiment, the calves were each intravenously dosed with 0.25 mc of Sr⁸⁵ at 4-, 14-, or 24-hr predialysis. Total Ca depletion of 0.16 g/hr resulted in a 4.8-fold turnover of plasma calcium after 12 hr of dialysis, while only decreasing the plasma Ca concentration by 26%. Plasma P concentration was decreased only 25% by 12-hr dialyses. Plasma concentrations of all isotopes declined (P<0.01) during dialysis. The radioactivity removed by dialysis decreased as the time after dosing increased. By the observed ratio technique, depleted Sr⁸⁹ to Ca⁴⁵ averaged 1.3–1.4, which confirms the data that Ca is bound to the plasma proteins more than Sr. Rib epiphyseal Ca⁴⁵ showed a significant decrease (P<0.05) after dialysis. Each isotope followed this trend in a proportional manner. Sr⁸⁵ activity in the epiphyseal rib increased during dialyses, begun 4 hr post-dosing. Ability of the young calf to mobilize reserve calcium, strontium, and phosphate was demonstrated in this study.

¹ This manuscript is published with permission of the Director of the University of Tennessee Agricultural Experiment Station, Knoxville, and the Director of the Maryland Agricultural Experiment Station, College Park. University of Maryland Scientific Article no. A-1210, Contribution no. 3712.

² Data taken from Master of Science thesis of H. F. Downey, submitted to the Graduate School University of Maryland, February, 1964.

³ Oak Ridge Institute of Nuclear Studies (ORINS) Fellow, 1963–64. Present address: Department of Physiology and Biophysics, University of Illinois, Urbana.

⁴ Department of Dairy Science, University of Maryland, College Park.

⁵ Supported by ORINS Contract S-936.

⁶ Operated by the Tennessee Agricultural Experiment Station for the U. S. Atomic Energy Commission under Contract no. AT-40-1-GEN-242.