Comparative study of different methods of inducing acute and chronic hypercalcemia in rats

Experimental studies are frequently carried out using calcium salt treatment in rats. Modifications in plasma calcium levels could suggest important changes in cellular functions, transmitters and drug responses. Changes during continuous maintenance of hypercalcemia could, on the other hand, be different from those produced by an acute increase in calcemia. Nevertheless, to date no specific studies exist which evaluate and compare the modifications in calcemia and other alterations when different methods of administering acute and chronic calcium are used in rats. This paper presents a method for inducing acute hypercalcemia in Sprague-Dawley rats after intraperitoneal administration of different quantities of CaCl2. Different oral calcium treatments to induce chronic hypercalcemia were also evaluated. Hypercalcemia was more consistent when calcium was administered in both the solid and liquid diets. On day 14 of treatment the highest total and ionic plasma calcium levels appeared in rats fed with CaCO3 in the solid diet (4% Ca) and with CaCl2 in the liquid diet (1.5% Ca). With this treatment hypercalcemia was maintained for 2 months.