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Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels.

Hoe SZ, Lee CN, Mok SL, Kamaruddin MY, Lam SK - Clinics (Sao Paulo) (2011)

Bottom Line: The effect of butanolic fraction on vascular reactivity was recorded in isolated rat aortic rings in vitro.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).

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. hoesz@ummc.edu.my

ABSTRACT

Introduction: Gynura procumbens has been shown to decrease blood pressure via inhibition of the angiotensinconverting 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 × 10⁻²M) 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.

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Related in: MedlinePlus

Effects of butanolic fraction (BU) obtained from Gynura procumbens crude ethanolic extract on the mean arterial pressure (MAP) (a) and heart rate (HR) (b) of anaesthetized rats. Values are mean±S.E.M. (n = 6). *p<0.05 and ***p<0.001, compared with the controls.
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f1-cln_66p143: Effects of butanolic fraction (BU) obtained from Gynura procumbens crude ethanolic extract on the mean arterial pressure (MAP) (a) and heart rate (HR) (b) of anaesthetized rats. Values are mean±S.E.M. (n = 6). *p<0.05 and ***p<0.001, compared with the controls.

Mentions: Intravenous administrations of BU (2.5–20 mg/kg) induced immediate and dose‐dependent decreases in MAP and HR (Figure 1). BU‐induced hypotension and bradycardia became significant (p<0.05) at doses of 2.5 and 10.0 mg/kg, respectively. The hypotensive effect was maximal within the first 20 to 30 s after BU treatment. Pre‐dose baseline levels were fully recovered within 10 min after BU administration. The effective dose that produced a 50% reduction in the MAP (ED50) was 4.77 mg/kg of BU.


Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels.

Hoe SZ, Lee CN, Mok SL, Kamaruddin MY, Lam SK - Clinics (Sao Paulo) (2011)

Effects of butanolic fraction (BU) obtained from Gynura procumbens crude ethanolic extract on the mean arterial pressure (MAP) (a) and heart rate (HR) (b) of anaesthetized rats. Values are mean±S.E.M. (n = 6). *p<0.05 and ***p<0.001, compared with the controls.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3044591&req=5

f1-cln_66p143: Effects of butanolic fraction (BU) obtained from Gynura procumbens crude ethanolic extract on the mean arterial pressure (MAP) (a) and heart rate (HR) (b) of anaesthetized rats. Values are mean±S.E.M. (n = 6). *p<0.05 and ***p<0.001, compared with the controls.
Mentions: Intravenous administrations of BU (2.5–20 mg/kg) induced immediate and dose‐dependent decreases in MAP and HR (Figure 1). BU‐induced hypotension and bradycardia became significant (p<0.05) at doses of 2.5 and 10.0 mg/kg, respectively. The hypotensive effect was maximal within the first 20 to 30 s after BU treatment. Pre‐dose baseline levels were fully recovered within 10 min after BU administration. The effective dose that produced a 50% reduction in the MAP (ED50) was 4.77 mg/kg of BU.

Bottom Line: The effect of butanolic fraction on vascular reactivity was recorded in isolated rat aortic rings in vitro.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).

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. hoesz@ummc.edu.my

ABSTRACT

Introduction: Gynura procumbens has been shown to decrease blood pressure via inhibition of the angiotensinconverting 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 × 10⁻²M) 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.

Show MeSH
Related in: MedlinePlus