Binding properties of duodenal 1,25-dihydroxyvitamin D3 receptors as affected by phosphorus depletion in lactating goats.
1. Capacity and affinity of duodenal 1,25(OH)2D3 receptors were measured in P depleted goats and in control animals kept on an adequate P supply. Plasma concentrations of Pi, Ca and vitamin D3 metabolites and activity of plasma alkaline phosphatase were measured to characterize the effects of P depletion. 2. During P depletion plasma Pi concentrations decreased significantly whereas plasma Ca and alkaline phosphatase activity increased. No changes were recorded for plasma vitamin D3, 25OHD3 and 1,25(OH)2D3 concentrations. 3. P depletion resulted in a significant decrease of the equilibrium dissociation constant Kd of duodenal 1,25(OH)2D3 receptors without affecting the maximum binding capacity.
Schröder
B
B
Department of Physiology, School of Veterinary Medicine, Hannover, FRG.
Breves
G
G
Pfeffer
E
E
D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001667:Binding, Competitive / Q000502:physiology; D002117:Calcitriol / Q000378:metabolism*; D004386:Duodenum / Q000378:metabolism*; D005260:Female; D006041:Goats / Q000378:metabolism*; D007774:Lactation / Q000378:metabolism*; D010758:Phosphorus / Q000172:deficiency*; D016226:Phosphorus, Dietary / Q000494:pharmacology; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000378:metabolism*
D016226:Phosphorus, Dietary; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D010758:Phosphorus; D000469:Alkaline Phosphatase; D002117:Calcitriol