Probenecid enhances relaxation induced by cyclic adenosine monophosphate- and cyclic guanosine monophosphate-augmenting substances in rat prostate, bladder, and corpus cavernosum: a potential repurposing strategy.

Prostate, bladder, and corpus cavernosum share common pathophysiological mechanisms involving smooth muscle tone regulation through cyclic nucleotide signaling, particularly cAMP and cGMP pathways. Probenecid, a classical uricosuric agent, has emerged as a candidate for drug repurposing due to its ability to inhibit multidrug resistance-associated proteins 4/5 (MRP4/MRP5), which mediate the cellular efflux of cyclic nucleotides, as well as pannexin-1 channels, organic anion transporters, TRPV2 channels, and purinergic receptors. Given that lower urinary tract symptoms, benign prostatic hyperplasia, and erectile dysfunction frequently coexist and share overlapping signaling pathways, we hypothesized that probenecid could potentiate smooth muscle relaxation mediated by cAMP- or cGMP-elevating agents across these tissues. Using isolated rat bladder, prostate, and corpus cavernosum, we evaluated the functional effects of probenecid (0.1-1 mM) through concentration-response curves and intracellular cyclic nucleotide quantification. Probenecid potentiated relaxation induced by β-adrenoceptor agonists and adenosine in the bladder, accompanied by increased intracellular cAMP without changes in cGMP. In prostate, probenecid enhanced relaxation induced by cAMP- and cGMP-elevating agents and increased intracellular cAMP when combined with salbutamol. In corpus cavernosum, probenecid induced relaxation per se and potentiated responses to acetylcholine, sodium nitroprusside, phosphodiesterase inhibitors, and β-agonists, with concurrent increases in both cAMP and cGMP. Selective tools targeting OAT1/3, P2X7 receptor and TRPV2 channels did not replicate these effects, whereas pannexin-1 inhibition potentiated acetylcholine-induced relaxation only in the corpus cavernosum. In conclusion, probenecid modulates smooth muscle relaxation across urogenital tissues and may represent a potential adjunct in the treatment of lower urinary tract symptoms and erectile dysfunction.