Diverse actions of calcitonin gene-related peptide on intracellular free Ca 2+ concentrations in UMR 106 osteoblastic cells

• Published in: Bone (New York, N.Y.) Vol. 16; no. 4; pp. S379 - S384
• Main Authors: Kawase, T., Howard, G.A., Roos, B.A., Burns, D.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1995
• Subjects: ATP-dependent potassium channel; Calcitonin gene-related peptide; Intracellular free calcium; Osteoblast-like cells; Osteosarcoma cells; Calcitonin gene-related peptide; ATP-dependent potassium channel; Osteoblast-like cells; Osteosarcoma cells; Intracellular free calcium
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/S8756-3282(95)80457-9

Calcitonin gene-related peptide (CGRP) was examined for its effects on intracellular free Ca 2+ concentration ([Ca 2+] i) in UMR 106 osteoblast-like cells. Cells loaded with the Ca 2+ dye FURA-2 dose-dependently responded to CGRP (1–100 nM) with transient two-fold increases in [Ca 2+] i. An intracellular source for this Ca 2+ transient was suggested by the failure of membrane depolarization with high extracellular K + or acute depletion of extracellular Ca 2+ ([Ca 2+] e) with EGTA to attenuate this response. After cells were incubated for 45 min with 0.1 mM extracellular Ca 2+ to deplete intracellular Ca 2+ stores, CGRP produced a 25–30% decrease in [Ca 2+] i rather than a transient increase. This calcium decrease was mimicked by membrane depolarization or by pinacidil, a specific activator of adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, and blocked by glybenclamide, a specific blocker of K ATP channels. Our data suggest that CGRP has diverse Ca 2+ regulatory effects in UMR 106 cells, mobilizing Ca 2+ from intracellular stores via classical signaling while possibly promoting cellular Ca 2+ efflux or inhibiting uptake through voltage-dependent Ca 2+ channels via K ATP-mediated hyperpolarization.