NPS-2143

NPS-2143 (SB262470) is a selective potent calcium ion-sensing receptor antagonist with IC50 of 43 and 41 nM for cytoplasmic Ca2+ concentrations and parathyroid hormone secretion, respectively. NPS-2143 blocks increases in cytoplasmic Ca2+ concentrations elicited by human Ca2+ receptors expressed in HEK293 cells . NPS-2143 (SB262470), even at much higher concentrations (3 μM), did not influence the activity of a number of other G protein-coupled receptors, including those most structurally homologous to the Ca2+ receptor.NPS-2143 (SB262470) also stimulates parathyroid hormone secretion from bovine parathyroid cells . In addition, administration of NPS-2143 resulted in moderate but sustained increases in plasma PTH levels and marked increases in bone formation and resorption with no net bone gain or loss.