Modulators of Ion Transport in Nasal Polyps: An in situ Measurement of Short-Circuit Current

OBJECTIVES To examine possible modulators of the ion transport through the apical membrane of the nasal polyps. METHODS The study was conducted using the freshly-excised nasal polyps from the patients with chronic sinusitis. A voltage-sensitive vibrating probe technique was introduced to monitor the short-circuit current across the apical membrane of the polyp at 37°C. RESULTS In the presence of amiloride, Adenosine 5'-triphosphate induced 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid-sensitive chloride current. Uridine 5'-diphosphate was less potent than Uridine 5'-triphosphate, and adenosine increased chloride secretion, which was blocked by the antagonist, 8-(p-sulfophenyl) theophylline on adenosine receptor. Based on the pharmacologic profiles, multiple purinergic receptors, including P2Y₂, P2Y₆, and P1 receptors, were functionally expressed. However, P2X receptor agonists (α,β-methyleneadenosine 5'-triphosphate and 2'- & 3'-O-[4-benzoyl-benzoyl] adenosine 5'-triphosphate), Cystic fibrosis conductance regulator (CFTR) activator (genistein), nitric oxide substrate (L-arginine), and nitric oxide donor (sodium nitroprusside) had no significant effect on the short circuit current. CONCLUSION Among tested drugs, P2Y receptor agonists were major modulators of ion transport in nasal polyps in situ.