Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA322

Poster Communications

Parastrephia quadrangularis (Meyen) Cabrera exerts a hypotensive effect on rats through a negative inotropic effect and endothelium-dependent vasodilation

J. Palacios1, A. Paredes2, C. Gutiérrez2, C. Nwokocha3, J. Bórquez4, M. Simirgiotis5, F. Cifuentes2

1. Instituto de Etnofarmacología, Facultad de Ciencias de la Salud. Universidad Arturo Prat, Iquique, Chile. 2. Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile. 3. Basic Medical Sciences, University of The West Indies Mona, Kinstong, Jamaica. 4. Departamento de Química, Universidad de Antofagasta, Antofagasta, Chile. 5. Instituto de Farmacia, Universidad Austral de Chile, Valdivia, Chile.

  • Parastrephia quadrangularis (Meyen) Cabrera

Parastrephia quadrangularis (Pq) is an endemic species of the Andes Cordillera, popularly known as "Tola". It has a wide use in folk medicine to treat altitude sickness. The purpose of the study was to evaluate the cardiovascular effects and the vascular response of the hydroalcoholic extract of P. quadrangularis (HAE Pq) and its pure isolated compounds. Methods: Several metabolites were isolated from the P. quadrangularis, and their structures were characterized by nuclear magnetic resonance (NMR), and mass spectrometry. Male Sprague-Dawley rats (6-8 weeks of age, 130-180g) were used. The animals were anesthetized with ketamine (42 mg/Kg, i.p.) and xylazine (5 mg/Kg, i.p.). Blood pressures recordings were recorded from the carotid artery of rats receiving HAE Pq (40 mg/Kg) through gavage for 10 days. The isolated right atrium and isolated heart of rat (Langendorff) were used to study the cardiac functions. The vascular response to HAE Pq and its pure compounds were evaluated in rat aorta. Values are means ± S.E.M., compared by ANOVA. The experiments of this study were conducted following the ARRIVE guidelines. Results: The oral treatment with HAE Pq (40 mg/Kg b.w.) significantly reduced the mean arterial blood pressure (MAP; 87±5 mmHg control vs. 66±1 mmHg with 40 mg/Kg HAE Pq; p<0.05, n=4) and the diastolic blood pressure (DBP; 75±6 mmHg control vs. 49±1 mmHg with 40 mg/Kg HAE Pq; p<0.01) in normotensive rats. HAE Pq did not cause a significant decrease in the heart rate or the beating frequency of rat right atrium. The decrease of the MAP could be a result of a negative inotropic effect (Left ventricular pressure 75±4 mmHg basal vs. 51±1 mmHg with 100 mg/mL HAE Pq; p<0.05, n=5), and an enhancement of the vascular endothelial relaxation (29±9 % in endothelium-denuded aorta vs. 58±7 % in intact aorta; 100 mg/mL HAE Pq; p<0.001, n=5). Seven metabolites were isolate from HAE Pq, but four metabolites (10-4 M) showed similar vasodilation to extract in intact rat aorta (111±4% with 100 mg/mL HAE Pq; n=5): 5,3'4'-trihydroxy-7-methoxyflavanone (99±4%), 5-hydroxy-7,4',3'-trimethoxyflavanone (79±11%), 3,5,4'-trihydroxy-7,8,3'-trimethoxyflavone (93±9%) and 5,4'-dihydroxy-3,7,8,3'-tetramethoxyflavone (119±11%). In conclusion, oral administration of Pq decreases the blood pressure in normotensive animals, in part, by decreasing of cardiac contractility and increasing vasodilation response. These findings support the use of Pq in folk medicine.

Where applicable, experiments conform with Society ethical requirements