Dose-time pattern of the hypercalcemic response to calcium infusion in the dog

Forty-five tests were performed to study blood total [Ca] response to a 2-hours IV calcium gluconate infusion, in five conscious dogs. Calcium doses were : 2.45 ; 4.50;6.19 and 9.00 mumole kg--u min-1 ; saline was used as control. Blood samples were collected every 20 minutes and calcaemia determined by atomic absorption spectrophotometry at 422.7 nm. No plateau was reached except with lowest dose. At each Ca dose, successive calcaemia levels can be fitted by a straight line and the regression calculated. With studied doses, calculated slopes were : 3.6 ; 8.3 ; 11.8 and 19.1 mumole l--1 min--1 respectively ; these slopes were found to be significantly different from each other. A linear dose-response relationship was calculated between blood [Ca] increase rate and Ca dose : Y = --3.01 + 2.44 X (mumole l--1 min-1 increase rate per mumole kg--1 min-1 Ca dose). Correspondence analysis emphazises the influence of zero time calcaemia.