Ana O. Hoff, Philip Catala-Lehnen, Pamela M. Thomas, Matthias Priemel, Johannes M. Rueger, Igor Nasonkin, Allan Bradley, Mark R. Hughes, Nelson Ordonez, Gilbert J. Cote, Michael Amling, Robert F. Gagel
PTH-stimulated bone resorption in KO mice causes hypercalcemia and is blocked by CT administration. Groups of five WT (gray bars) or KO (black bars) male mice were injected intraperitoneally with human PTH or vehicle (PBS with 0.1 mM HCl and 0.01% BSA) and sacrificed at the indicated times with collection of serum and urine. (a) In KO animals, human PTH stimulates a 4 mg% rise in serum calcium concentration and a doubling of urine DPD during the first 2 hours of the experiment. No significant change of serum calcium or urine DPD was seen in WT animals treated with PTH or vehicle at any timepoint. (b) Measurement of serum CT demonstrated a significant increase in WT animals (open circles) and no detectable CT in KO animals (filled circles). (c) Groups of male mice were injected intramuscularly in the thigh with vehicle, rat CT (10, 100, or 1,000 pg/g mouse body weight) (filled circles), or rat CGRP (11.2, 112, or 1,120 pg/g mouse body weight) (filled squares), followed 3 minutes later by an intraperitoneal injection with human PTH (or vehicle, in the case of the control). Blood was collected 1 hour after the initial intramuscular injection. (d) Experiments were performed as in c but at higher dosage. All experiments included five animals per group with bars representing mean ± SD. *P < 0.05.