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Effect of quercetin on tachykinin‐induced plasma extravasation in rat urinary bladder

2001; Wiley; Volume: 15; Issue: 5 Linguagem: Inglês

10.1002/ptr.974

1099-1573

Paulo Roberto Wille, Rosa Maria Ribeiro‐do‐Valle, Cláudia Maria Oliveira Simões, Nelson H. Gabilan, Mauro Nicolau,

Nitric Oxide and Endothelin Effects

Abstract The effect of quercetin on substance P‐induced plasma extravasation in rat urinary bladder and its modulation by endogenous peptidases in conscious rats was studied. Plasma protein extravasation (PE) was assayed by measurement of extravasated Evans blue dye (μg/g dry tissue). Intravenous injection of substance P (SP, 10 nmol/kg) significantly increased PE in the urinary bladder. PE evoked by SP was increased significantly by quercetin (20 mg/kg, p.o.) pretreatment in the urinary bladder (73.5 ± 4.9 to 152.2 ± 9.9). Pretreatment with captopril, an angiotensin‐converting enzyme (ACE) inhibitor (10 nmol/kg, i.v.), or with phosphoramidon, a neutral endopeptidase (NEP) inhibitor (2.5 μmol/kg, i.v.) also potentiated the SP‐induced PE in urinary bladder, 286.2 ± 20.4 and 323.3 ± 34.0, respectively. Quercetin did not show any effect on neurokinin‐A (NKA, 10 nmol/kg, i.v.) ‐induced plasma extravasation. The present study demonstrates that quercetin potentiates the PE induced by substance P in the urinary bladder. These effects suggest that this flavonoid might cause inhibition of NEP and/or ACE. Copyright © 2001 John Wiley & Sons, Ltd.