title: Hypotensive and diuretic effect of the butanolic soluble fraction of the hydroethanolic extract of bark of Scutia buxifolia Reissek in rats.
abstract: BACKGROUND
  Scutia buxifolia, a native tree popularly known as "coronilha", is widely used in Brazilian folk medicine for diuretic and anti-hypertensive purposes.
  
  
  OBJECTIVE
  We investigated the effects of a butanolic (BuOH) soluble fraction of the hydroethanolic extract (HESB) of bark of Scutia buxifolia on both blood pressure and urinary excretion of rats. The involvement of the nitric oxide/guanylate cyclase pathway in the hypotensive effect found was also explored.
  
  
  METHODS
  We tested the effect of the BuOH soluble fraction of HESB on the mean arterial pressure (MAP) of anesthetized rats. The fraction was administered at doses of 1, 3 and 10mg/kg (i.v.) in normotensive rats during continuous infusion of vehicle (10 μl/min), or phenylephrine (4 μg/kg/min), or l-NAME (7 mg/kg/min), two approaches able to induce a sustained hypertensive state. In some experiments, a bolus injection of ODQ (2mg/kg) was administered in animals infused with phenylephrine before the administration of the BuOH soluble fraction of HESB. We also measured the effects of the BuOH soluble fraction on the MAP of spontaneously hypertensive rats (SHR). Separate groups of rats were treated orally with either HESB (10, 30 or 100mg/kg), or its BuOH soluble fraction (3, 10 or 30 mg/kg), and were subjected to measurement of diuresis and blood pressure.
  
  
  RESULTS
  The BuOH soluble fraction of HESB (10mg/kg, i.v.) reduced the MAP of both phenylephrine-infused and SHR rats by 20.6 ± 6.0 and 41.8 ± 8.3 mm Hg, respectively. However, no hypotensive effect was found in normotensive animals infused with l-NAME, a non-selective inhibitor of nitric oxide synthase, or animals previously treated with the soluble guanylate cyclase inhibitor ODQ. The urinary excretion was increased by 70% at 6-8h after a single oral administration of the BuOH soluble fraction of HESB (10mg/kg), without change in urinary density, pH, or Na(+) and K(+) concentrations. In addition, MAP was lower 3h after the acute oral treatment with the BuOH soluble fraction (82.1 ± 3.8 mm Hg), compared with MAP of animals from the control group (97 ± 3.2 mm Hg).
  
  
  CONCLUSIONS
  This study demonstrates that the BuOH soluble fraction of the hydroethanolic bark of Scutia buxifolia, which has its bark used in folk medicine for the treatment of hypertension mainly by its presumed diuretic properties, possesses both diuretic and hypotensive effects in rats, and that at least the hypotensive effect is fully dependent on activation of the nitric oxide/guanylate cyclase pathway.
authors.affiliation: Department of Pharmacology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors.forename: Rita de C V de A F
authors.initials: Rde C
authors.lastname: Da Silva
authors.affiliation: Department of Pharmacology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors.forename: Priscila
authors.initials: P
authors.lastname: de Souza
authors.affiliation: Department of Pharmacology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors.forename: Sandra
authors.initials: S
authors.lastname: Crestani
authors.affiliation: Faculty of Health Sciences, Universidade Federal da Grande Dourados, Dourados, MS, Brazil.
authors.forename: Arquimedes
authors.initials: A
authors.lastname: Gasparotto Júnior
authors.affiliation: Department of Industrial Pharmacy, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Aline A
authors.initials: AA
authors.lastname: Boligon
authors.affiliation: Department of Industrial Pharmacy, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
authors.forename: Margareth L
authors.initials: ML
authors.lastname: Athayde
authors.affiliation: Department of Pharmacology, Universidade Federal do Paraná, Curitiba, PR, Brazil; Laboratory of Cardiovascular Pharmacology, Department of Pharmacology, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil. Electronic address: j.e.silva.santos@ufsc.br.
authors.forename: José Eduardo
authors.initials: JE
authors.lastname: da Silva-Santos
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001938:Brazil; D004195:Disease Models, Animal; D004232:Diuretics / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006162:Guanylate Cyclase / Q000378:metabolism; D006973:Hypertension / Q000188:drug therapy; D008297:Male; D008519:Medicine, Traditional; D009569:Nitric Oxide / Q000378:metabolism; D024301:Plant Bark; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D027823:Rhamnaceae / Q000737:chemistry*
chemical_list: D000959:Antihypertensive Agents; D004232:Diuretics; D010936:Plant Extracts; D009569:Nitric Oxide; D006162:Guanylate Cyclase
keywords: 1H-[1,2,4] oxadiazolo[4,3-a] quinoxalin-1-one (PubChem CID: 1456); Acethylcholine chloride (PubChem CID 6060); Anti-hypertensive; Dimethyl sulfoxide (PubChem CID 679); Diuretic; Furosemide (PubChem CID 3440); Hypertension; L-NAME (PubChem CID 39836); Nitric oxide; Phenylephrine hydrochloride (PubChem CID: 5284443); Scutia buxifolia Reissek