Osteoblasts from female and male rats exhibit differential responses to 1α,25(OH)
when cultured on tissue culture polystyrene. Osteoblasts isolated from the calvaria of female and male rats were treated for 24 hours with increasing concentrations of the vitamin D metabolite 1α,25(OH)2D3 at confluence. Cell number (A), alkaline phosphatase specific activity in cell lysates (B) and osteocalcin in the conditioned media (C) were measured after 24 hours of treatment with either vehicle, 10-9M 1α,25(OH)2D3 or 10-8M 1α,25(OH)2D3. *P < 0.05, 1α,25(OH)2D3 treatment versus control; #p < 0.05, 10-9M 1α,25(OH)2D3 treatment versus 10-8M treatment.