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Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels
INTRODUCTION: Gynura procumbens has been shown to decrease blood pressure via inhibition of the angiotensin‐converting enzyme. However, other mechanisms that may contribute to the hypotensive effect have not been studied. OBJECTIVES: To investigate the cardiovascular effects of a butanolic fraction...
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Formato: | Texto |
Lenguaje: | English |
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Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo
2011
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3044591/ https://www.ncbi.nlm.nih.gov/pubmed/21437451 http://dx.doi.org/10.1590/S1807-59322011000100025 |
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author | Hoe, See‐Ziau Lee, Chen‐Neng Mok, Shiueh‐Lian Kamaruddin, Mohd Yusoff Lam, Sau‐Kuen |
author_facet | Hoe, See‐Ziau Lee, Chen‐Neng Mok, Shiueh‐Lian Kamaruddin, Mohd Yusoff Lam, Sau‐Kuen |
author_sort | Hoe, See‐Ziau |
collection | PubMed |
description | INTRODUCTION: Gynura procumbens has been shown to decrease blood pressure via inhibition of the angiotensin‐converting enzyme. However, other mechanisms that may contribute to the hypotensive effect have not been studied. OBJECTIVES: To investigate the cardiovascular effects of a butanolic fraction of Gynura procumbens in rats. METHODS: Anaesthetized rats were given intravenous bolus injections of butanolic fraction at doses of 2.5–20 mg/kg in vivo. The effect of butanolic fraction on vascular reactivity was recorded in isolated rat aortic rings in vitro. RESULTS: Intravenous administrations of butanolic fraction elicited significant (p<0.001) and dose‐dependent decreases in the mean arterial pressure. However, a significant (p<0.05) decrease in the heart rate was observed only at the higher doses (10 and 20 mg/kg). In isolated preparations of rat aortic rings, phenylephrine (1×10(‐6) M)‐ or potassium chloride (8×10(‐2) M)‐precontracted endothelium‐intact and ‐denuded tissue; butanolic fraction (1×10(‐6)–1×10(‐1) g/ml) induced similar concentration‐dependent relaxation of the vessels. In the presence of 2.5×10(‐3) and 5.0×10(‐3) g/ml butanolic fraction, the contractions induced by phenylephrine (1×10(‐9)–3×10(‐5) M) and potassium chloride (1×10(‐2)–8×10(‐2) M) were significantly antagonized. The calcium‐induced vasocontractions (1×10(‐4)–1×10(‐2) M) were antagonized by butanolic fraction concentration‐dependently in calcium‐free and high potassium (6×10(‐2) M) medium, as well as in calcium‐ and potassium‐free medium containing 1×10(‐6) M phenylephrine. However, the contractions induced by noradrenaline (1×10(‐6) M) and caffeine (4.5×10(‐2) M) were not affected by butanolic fraction. CONCLUSION: Butanolic fraction contains putative hypotensive compounds that appear to inhibit calcium influx via receptor‐operated and/or voltage‐dependent calcium channels to cause vasodilation and a consequent fall in blood pressure. |
format | Text |
id | pubmed-3044591 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2011 |
publisher | Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo |
record_format | MEDLINE/PubMed |
spelling | pubmed-30445912011-02-24 Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels Hoe, See‐Ziau Lee, Chen‐Neng Mok, Shiueh‐Lian Kamaruddin, Mohd Yusoff Lam, Sau‐Kuen Clinics (Sao Paulo) Basic Research INTRODUCTION: Gynura procumbens has been shown to decrease blood pressure via inhibition of the angiotensin‐converting enzyme. However, other mechanisms that may contribute to the hypotensive effect have not been studied. OBJECTIVES: To investigate the cardiovascular effects of a butanolic fraction of Gynura procumbens in rats. METHODS: Anaesthetized rats were given intravenous bolus injections of butanolic fraction at doses of 2.5–20 mg/kg in vivo. The effect of butanolic fraction on vascular reactivity was recorded in isolated rat aortic rings in vitro. RESULTS: Intravenous administrations of butanolic fraction elicited significant (p<0.001) and dose‐dependent decreases in the mean arterial pressure. However, a significant (p<0.05) decrease in the heart rate was observed only at the higher doses (10 and 20 mg/kg). In isolated preparations of rat aortic rings, phenylephrine (1×10(‐6) M)‐ or potassium chloride (8×10(‐2) M)‐precontracted endothelium‐intact and ‐denuded tissue; butanolic fraction (1×10(‐6)–1×10(‐1) g/ml) induced similar concentration‐dependent relaxation of the vessels. In the presence of 2.5×10(‐3) and 5.0×10(‐3) g/ml butanolic fraction, the contractions induced by phenylephrine (1×10(‐9)–3×10(‐5) M) and potassium chloride (1×10(‐2)–8×10(‐2) M) were significantly antagonized. The calcium‐induced vasocontractions (1×10(‐4)–1×10(‐2) M) were antagonized by butanolic fraction concentration‐dependently in calcium‐free and high potassium (6×10(‐2) M) medium, as well as in calcium‐ and potassium‐free medium containing 1×10(‐6) M phenylephrine. However, the contractions induced by noradrenaline (1×10(‐6) M) and caffeine (4.5×10(‐2) M) were not affected by butanolic fraction. CONCLUSION: Butanolic fraction contains putative hypotensive compounds that appear to inhibit calcium influx via receptor‐operated and/or voltage‐dependent calcium channels to cause vasodilation and a consequent fall in blood pressure. Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo 2011-01 /pmc/articles/PMC3044591/ /pubmed/21437451 http://dx.doi.org/10.1590/S1807-59322011000100025 Text en Copyright © 2011 Hospital das Clínicas da FMUSP http://creativecommons.org/licenses/by-nc/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Basic Research Hoe, See‐Ziau Lee, Chen‐Neng Mok, Shiueh‐Lian Kamaruddin, Mohd Yusoff Lam, Sau‐Kuen Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels |
title | Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels |
title_full | Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels |
title_fullStr | Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels |
title_full_unstemmed | Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels |
title_short | Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels |
title_sort | gynura procumbens merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels |
topic | Basic Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3044591/ https://www.ncbi.nlm.nih.gov/pubmed/21437451 http://dx.doi.org/10.1590/S1807-59322011000100025 |
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