Alpha-2-adrenergic modulation of the parathyroid hormone-inhibition of phosphate uptake in cultured renal (OK) cells.

Parathyroid hormone enhances the formation of cAMP and decreases the Na+-dependent uptake of phosphate in cultured renal cells derived from the American opossum (OK cells). Epinephrine, acting as an alpha 2-adrenergic agonist, inhibits the PTH-induced synthesis of cAMP by a pertussis toxin-sensitive mechanism and blunts the inhibition of phosphate transport by PTH. Na+-dependent alpha-methylglucoside and Na+ uptakes by the cells are unaffected by PTH and epinephrine. These findings suggest that alpha 2-adrenergic agonists may selectively modulate PTH-sensitive phosphate transport in the renal proximal tubule.