1,25-Dihydroxycholecalciferol regulates salivary phosphate secretion in cattle.
The influence of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) on salivary inorganic phosphorus (Pi) concentration and secretion was studied in two groups of four heifers, the right parotid ducts of which were chronically fitted with a re-entrant cannula. In four heifers i.v. Pi loading (5 mmol/min for 2 h) induced hyperphosphataemia associated with a decrease in plasma 1,25-(OH)2D concentration and an increase in salivary Pi concentration and secretion. In four other heifers, daily 1 alpha-hydroxycholecalciferol injections (1 microgram/kg body wt per day for 3 days) induced hyperphosphataemia associated with an increase in plasma 1,25-(OH)2D concentration and a decrease in salivary Pi concentration and secretion. These treatments had no significant effect on salivary calcium concentration and secretion. Our results indicate that plasma 1,25-(OH)2D concentrations rather than phosphataemia regulate salivary Pi concentration and secretion in cattle.
D000818:Animals; D002117:Calcitriol / Q000097:blood / Q000502:physiology*; D002417:Cattle / Q000378:metabolism*; D006887:Hydroxycholecalciferols / Q000494:pharmacology; D008297:Male; D010758:Phosphorus / Q000378:metabolism* / Q000494:pharmacology; D012463:Saliva / Q000378:metabolism*; D012636:Secretory Rate / Q000187:drug effects
D006887:Hydroxycholecalciferols; D010758:Phosphorus; D002117:Calcitriol; C008088:alfacalcidol