WR-2721 inhibits parathyroid adenylate cyclase

Area of Science:

• Biochemistry
• Endocrinology
• Pharmacology

Background:

• WR-2721 (S-2-(3-aminopropylamino)ethylphosphorothioic acid) is a known chemoprotective and radioprotective agent.
• Previous studies indicate WR-2721 lowers serum calcium in dogs and humans by affecting bone calcium release and parathyroid hormone (PTH) secretion.
• Cyclic adenosine monophosphate (cAMP) is implicated in regulating PTH secretion, and WR-2721 has been shown to decrease cAMP levels in mouse spleen.

Purpose of the Study:

• To investigate the effect of WR-2721 on cyclic adenosine monophosphate (cAMP) production in bovine parathyroid cells.
• To examine the impact of WR-2721 on adenylate cyclase activity in plasma membranes of bovine parathyroid glands.

Main Methods:

• Bovine parathyroid cells were incubated with varying concentrations of WR-2721 (0.02–2.0 mM) at 0.5 mM Ca2+.
• Adenylate cyclase activity was measured in plasma membranes isolated from bovine parathyroid glands after exposure to WR-2721.
• The effects of WR-2721 on basal and stimulated adenylate cyclase activity (using NaF, Gpp(NH)p, forskolin, and pertussin toxin) were assessed across a range of Mg2+ concentrations.

Main Results:

• WR-2721 caused a dose-dependent decrease in intracellular cAMP levels in parathyroid cells, ranging from 42% to 50%.
• Exposure to WR-2721 resulted in a dose-dependent inhibition of adenylate cyclase activity in bovine parathyroid gland plasma membranes.
• This inhibition of adenylate cyclase by WR-2721 was observed across a broad spectrum of Mg2+ concentrations and affected both basal and stimulated enzyme activity.

Conclusions:

• WR-2721 inhibits the activity of parathyroid adenylate cyclase.
• The findings suggest that WR-2721's ability to lower parathyroid hormone secretion may be mediated through the inhibition of parathyroid adenylate cyclase and subsequent reduction in cAMP production.