1,25-Dihydroxycholecalciferol (Calcitriol): Effect on Phosphate (PO4) Absorption by Isolated Pars Recta
Phosphate handling by the kidney is influenced by a number of factors including extracellular fluid volume, plasma calcium concentration, bicarbonate administration, parathyroid hormone, and dietary phosphate balance. Vitamin D metabolites have also been demonstrated to augment renal phosphate absorption in the presence and absence of PTH (1–6). Bonjour, Preston and Fleisch have demonstrated that calcitriol increases phosphate excretion in the thyropara-thyroidectomized rat (7), and Gloor, Bonjour, Caverzasio and Fleisch demonstrated that calcitriol prevents the renal resistance to the Phosphaturic response to PTH during phosphate depletion (8). These investigators localized the site of action of calcitriol to the proximal convoluted tubule and beyond the point of micropuncture in the distal tubule in the rat (9).
KeywordsParathyroid Hormone Fluid Absorption Phosphate Transport Extracellular Fluid Volume Tubule Segment
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