Expression of Voltage Sensitive Calcium Channel (VSCC) L-type Cav1.2 (alpha1C) and T-type Cav3.2 (alpha1H) Subunits During Mouse Bone Development

Voltage-sensitive calcium channels (VSCCs) are key regulators of osteoblast plasma membrane Ca(2+) permeability and are under control of calcitropic hormones. Subtype specific antibodies were used to probe L-type Ca(v)1.2 (alpha(1C)) and T-type Ca(v)3.2 (alpha(1H)) subunit expression during mouse skeletal development. Commencing from E14.5 and continuing through skeletal maturity, immunoreactivity of Ca(v)1.2 (alpha(1C)) subunits was evident in regions of rapid long bone growth, including the perichondrium, periosteum, chondro-osseous junction and trabecular bones. Ca(v)3.2 (alpha(1H)) subunits appeared simultaneously and followed a similar distribution pattern. Both subunits were observed in osteoblasts and chondrocytes under high magnification. Interestingly, Ca(v)3.2 (alpha(1H)) subunits were present, but Ca(v)1.2 (alpha(1C)) subunits were absent from osteocytes. Western Blot and immunohistochemical assessment of in vitro cell culture models of osteogenesis and chondrogenesis confirmed the in vivo observations. We conclude that both L-type Ca(v)1.2 (alpha(1C)) and T-type Ca(v)3.2 (alpha(1H)) VSCCs are dynamically regulated in bones and cartilages during endochondral bone development.