Probenecid

Cell experiment:

HEK-293T cells are transfected with hTAS2R expression constructs using Lipofectamine 2000 in poly-lysine coated, black 384-well plates with clear bottoms and incubated for 22 hours at 37°C. Growth media is removed and cells are washed twice with HBSS containing 20 mM HEPES, then loaded with a calcium indicator dye in HBSS containing 20 mM HEPES (Calcium 4 Assay kit) with or without 1 mM Probenecid. Cells are incubated at 37°C for 1 hour in the presence of both dye and Probenecid, then moved to a Flexstation II-384 set for 32°C. After a 15-minute temperature equilibration (without washout), indicated compounds are injected (at t=~25 seconds) and fluorescence is measured for 100 to 180 seconds, reading every 3 seconds. Data sets are analyzed and represented as % over baseline signal using Prism 5.0 software. For Schild plots, replicates of raw calcium flux values are expressed as % over baseline signal. The mean value at 36 seconds (corresponding to the maximum flux signal) for each concentration of TAS2R ligand in the presence of the indicated concentration of Probenecid is plotted against the log of ligand concentration. Data points are fit using non-linear regression in GraphPad Prism[1].

Animal experiment:

Mice[1] In order to obtain a dose response curve, male C57 WT (n=39) mice 12-16 weeks of age are anesthetized with isoflurane while intravenous jugular access (IV) is obtained under a microscope. Subsequently, an echocardiographic study with both M-mode and B-mode is obtained in parasternal long axis (PSLAX) as described below. Either saline or different doses of Probenecid (increasing from 2 to 200mg/kg) are injected (bolus IV) for the initial contractility studies in WT mice.

References:

[1]. Koch SE, et al. Probenecid: novel use as a non-injurious positive inotrope acting via cardiac TRPV2 stimulation. J Mol Cell Cardiol. 2012 Jul;53(1):134-44.
[2]. Bakos E, et al. Interactions of the human multidrug resistance proteins MRP1 and MRP2 with organic anions. Mol Pharmacol. 2000 Apr;57(4):760-8.
[3]. Greene TA, et al. Probenecid inhibits the human bitter taste receptor TAS2R16 and suppresses bitter perception of salicin. PLoS One. 2011;6(5):e20123.
[4]. Silverman W, et al. Probenecid, a gout remedy, inhibits pannexin 1 channels. Am J Physiol Cell Physiol. 2008 Sep;295(3):C761-7.