Given an abstract from a research paper, your task is to identify and label relationships between chemical compounds and genes mentioned in the abstract.

The relationship type must be one of ['DOWNREGULATOR', 'SUBSTRATE', 'INDIRECT-REGULATOR', 'PART-OF', 'MODULATOR-ACTIVATOR', 'REGULATOR', 'INHIBITOR', 'COFACTOR', 'UPREGULATOR', 'ACTIVATOR', 'ANTAGONIST', 'NOT', 'INDIRECT-DOWNREGULATOR', 'SUBSTRATE_PRODUCT-OF', 'INDIRECT-UPREGULATOR', 'AGONIST', 'PRODUCT-OF', 'MODULATOR', 'DIRECT-REGULATOR', 'UNDEFINED', 'AGONIST-INHIBITOR', 'AGONIST-ACTIVATOR', 'MODULATOR-INHIBITOR'].

Please format your output as a JSON array. Each entry in the array should express a single relation, formatted as ["<Entity_A>", "<RELATION_A_B>", "<Entity_B>"]. If no relations can be found, please output an empty JSON array [].

Abstract:

Pharmacological characterization of unique prazosin-binding sites in human kidney. In human kidney, we found unique prazosin-binding sites that were insensitive to phentolamine and were thus unlikely to be alpha (1) -adrenoceptors. As the binding of [ (3) H]prazosin to phentolamine-insensitive sites was prevented by 100 microM guanabenz, the insensitive sites were evaluated by subtracting [ (3) H]prazosin binding in the presence of 100 microM guanabenz from that in the presence of 10 microM phentolamine. [ (3) H]Prazosin bound to the phentolamine-insensitive sites monophasically with a high affinity (pK (d); 9.1+/-0.08, n=8), and the B (max) value (814+/-204 fmol mg (-1) protein, n=8) was more than ten times that of the phentolamine-sensitive alpha (1) -adrenoceptor (pK (d) =9.9+/-0.13, B (max) =66+/-23 fmol mg (-1) protein, n=7). The phentolamine-insensitive sites in human kidney were highly sensitive to other quinazoline derivatives such as terazosin and doxazosin. However, other alpha (1) -adrenoceptor antagonists (tamsulosin, WB4101 and corynanthine) did not inhibit the binding at a range of concentrations that generally exhibit alpha (1) -adrenoceptor antagonism, and noradrenaline, rauwolscine and propranolol were without effect on the [ (3) H]prazosin binding. On the other hand, ligands for the renal Na (+) -transporter (amiloride and triamterene) and for imidazoline recognition sites (guanabenz, guanfacine and agmatine) displaced the binding of [ (3) H]prazosin to phentolamine-insensitive sites at micromolar concentrations. Photoaffinity labeling with [ (125) I]iodoarylazidoprazosin showed phentolamine-insensitive labeling at around 100 kDa, a molecular size larger than that of human alpha (1a) - and alpha (1b) -adrenoceptors expressed in 293 cells (50-60 and 70-80 kDa, respectively) on electrophoresis. In contrast, there was no detectable phentolamine-insensitive binding site but were phentolamine-sensitive alpha (1) -adrenoceptors in human liver (pK (d) =10.0+/-0.06, B (max) =44+/-6 fmol mg (-1) protein, n=3). Phentolamine-insensitive prazosin binding sites were also detected in rabbit kidney (approximately 50% of specific binding sites) but were minor in rat kidney (less than 20%). In conclusion, there are unique prazosin-binding sites in human kidney, the pharmacological profiles of which were distinct from those of known adrenoceptors.
[["triamterene", "DIRECT-REGULATOR", "Na (+) -transporter"], ["tamsulosin", "ANTAGONIST", "alpha (1) -adrenoceptor"], ["corynanthine", "ANTAGONIST", "alpha (1) -adrenoceptor"], ["WB4101", "ANTAGONIST", "alpha (1) -adrenoceptor"], ["amiloride", "DIRECT-REGULATOR", "Na (+) -transporter"]]