The birdseed Phalaris canariensis (Pc) is popularly used as an antihypertensive agent. The aqueous extract of Pc (AEPc) was administered in adult normotensive Wistar rats and spontaneously hypertensive
rats (SHR) and in prehypertensive young SHR (SHRY, 3 weeks old). Animals received AEPc (400 mg·kg–1·day–1, by gavage) for 30 days, then groups were divided into 2 subgroups: one was treated for another 30 days and
the other received water instead of AEPc for 30 days. AEPc reduced systolic blood pressure (SBP) in both adult groups; however, treatment interruption was followed by a gradual return of the SBP to baseline levels. SHRY became hypertensive 30 days after weaning. AEPc minimized
the increase in SBP in SHRY, but blood pressure rose to levels similar to those in the untreated group with treatment interruption. There were no changes in renal function, diuresis, or Na+ excretion. Pc is rich in tryptophan, and the inhibition of the metabolism of tryptophan
to kynurenine, a potential vasodilator factor, prevented the blood pressure reducing effect of AEPc. Moreover, AEPc significantly reduced sympathoexcitation. Data indicate that the metabolic derivative of tryptophan, kinurenine, may be a mediator of the volume-independent antihypertensive
effect of Pc, which was at least in part mediated by suppression of the sympathetic tonus.
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Document Type: Research Article
Renal Division, Federal University of São Paulo (UNIFESP), Rua Botucatu, 740, 04023-900, São Paulo, Brazil.
Cardiovascular Division, Department of Physiology, Federal University of São Paulo, São Paulo, Brazil.
Publication date: February 20, 2012
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