Limits...
Brazilin isolated from the heartwood of Caesalpinia sappan L induces endothelium-dependent and -independent relaxation of rat aortic rings.

Yan Y, Chen YC, Lin YH, Guo J, Niu ZR, Li L, Wang SB, Fang LH, Du GH - Acta Pharmacol. Sin. (2015)

Bottom Line: The vasorelaxant effect of brazilin was significantly attenuated by endothelium removal or by pre-incubation with L-NAME, methylene blue or indomethacin.Brazilin induces relaxation in rat aortic rings via both endothelium-dependent and -independent ways as well as inhibiting NE-stimulated phosphorylation of ERK1/2 and MLC.Brazilin also attenuates vasoconstriction via blocking voltage- and receptor-operated Ca(2+) channels.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines Beijing 100050, China.

ABSTRACT

Aim: Brazilin is one of the major constituents of Caesalpinia sappan L with various biological activities. This study sought to investigate the vasorelaxant effect of brazilin on isolated rat thoracic aorta and explore the underlying mechanisms.

Methods: Endothelium-intact and -denuded aortic rings were prepared from rats. The tension of the preparations was recorded isometrically with a force displacement transducer connected to a polygraph. The phosphorylation levels of ERK1/2 and myosin light chain (MLC) were analyzed using Western blotting assay.

Results: Application of brazilin (10-100 μmol/L) dose-dependently relaxed the NE- or high K(+)-induced sustained contraction of endothelium-intact aortic rings (the EC50 was 83.51±5.6 and 79.79±4.57 μmol/L, respectively). The vasorelaxant effect of brazilin was significantly attenuated by endothelium removal or by pre-incubation with L-NAME, methylene blue or indomethacin. In addition, pre-incubation with brazilin dose-dependently attenuated the vasoconstriction induced by KCl, NE or Ang II. Pre-incubation with brazilin also markedly suppressed the high K(+)-induced extracellular Ca(2+) influx and NE-induced intracellular Ca(2+) release in endothelium-denuded aortic rings. Pre-incubation with brazilin dose-dependently inhibited the NE-stimulated phosphorylation of ERK1/2 and MLC in both endothelium-intact and -denuded aortic rings.

Conclusion: Brazilin induces relaxation in rat aortic rings via both endothelium-dependent and -independent ways as well as inhibiting NE-stimulated phosphorylation of ERK1/2 and MLC. Brazilin also attenuates vasoconstriction via blocking voltage- and receptor-operated Ca(2+) channels.

Show MeSH

Related in: MedlinePlus

Vasorelaxant effects of brazilin on endothelium-intact thoracic aorta rings pre-contracted with NE (1 μmol/L) or KCl (60 mmol/L). Brazilin dose-dependently relaxed NE (A and B) or KCl (C and D)-precontracted intact aorta. The relaxant effects of brazilin on isolated rat aortic rings were calculated as a percentage of the contraction in response to NE (1 μmol/L) (B) or KCl (60 mmol/L) (D). Data are expressed as mean±SEM. n=6.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4644902&req=5

fig2: Vasorelaxant effects of brazilin on endothelium-intact thoracic aorta rings pre-contracted with NE (1 μmol/L) or KCl (60 mmol/L). Brazilin dose-dependently relaxed NE (A and B) or KCl (C and D)-precontracted intact aorta. The relaxant effects of brazilin on isolated rat aortic rings were calculated as a percentage of the contraction in response to NE (1 μmol/L) (B) or KCl (60 mmol/L) (D). Data are expressed as mean±SEM. n=6.

Mentions: Brazilin inhibited the NE (1 μmol/L)-induced sustained contraction in the rat aortic rings in a dose-dependent manner; the 50% effective concentration (EC50) was 83.51±5.6 μmol/L, and the maximal relaxant effect (Emax) reached 66.51%±7.54% at a concentration of 100 μmol/L (Figure 2A, B). Brazilin also relaxed aortic rings pre-contracted with KCl (60 mmol/L) in a similar way (EC50=79.79±4.57 μmol/L, Emax=75.01%±5.8%, n=6) (Figure 2C, D).


Brazilin isolated from the heartwood of Caesalpinia sappan L induces endothelium-dependent and -independent relaxation of rat aortic rings.

Yan Y, Chen YC, Lin YH, Guo J, Niu ZR, Li L, Wang SB, Fang LH, Du GH - Acta Pharmacol. Sin. (2015)

Vasorelaxant effects of brazilin on endothelium-intact thoracic aorta rings pre-contracted with NE (1 μmol/L) or KCl (60 mmol/L). Brazilin dose-dependently relaxed NE (A and B) or KCl (C and D)-precontracted intact aorta. The relaxant effects of brazilin on isolated rat aortic rings were calculated as a percentage of the contraction in response to NE (1 μmol/L) (B) or KCl (60 mmol/L) (D). Data are expressed as mean±SEM. n=6.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4644902&req=5

fig2: Vasorelaxant effects of brazilin on endothelium-intact thoracic aorta rings pre-contracted with NE (1 μmol/L) or KCl (60 mmol/L). Brazilin dose-dependently relaxed NE (A and B) or KCl (C and D)-precontracted intact aorta. The relaxant effects of brazilin on isolated rat aortic rings were calculated as a percentage of the contraction in response to NE (1 μmol/L) (B) or KCl (60 mmol/L) (D). Data are expressed as mean±SEM. n=6.
Mentions: Brazilin inhibited the NE (1 μmol/L)-induced sustained contraction in the rat aortic rings in a dose-dependent manner; the 50% effective concentration (EC50) was 83.51±5.6 μmol/L, and the maximal relaxant effect (Emax) reached 66.51%±7.54% at a concentration of 100 μmol/L (Figure 2A, B). Brazilin also relaxed aortic rings pre-contracted with KCl (60 mmol/L) in a similar way (EC50=79.79±4.57 μmol/L, Emax=75.01%±5.8%, n=6) (Figure 2C, D).

Bottom Line: The vasorelaxant effect of brazilin was significantly attenuated by endothelium removal or by pre-incubation with L-NAME, methylene blue or indomethacin.Brazilin induces relaxation in rat aortic rings via both endothelium-dependent and -independent ways as well as inhibiting NE-stimulated phosphorylation of ERK1/2 and MLC.Brazilin also attenuates vasoconstriction via blocking voltage- and receptor-operated Ca(2+) channels.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines Beijing 100050, China.

ABSTRACT

Aim: Brazilin is one of the major constituents of Caesalpinia sappan L with various biological activities. This study sought to investigate the vasorelaxant effect of brazilin on isolated rat thoracic aorta and explore the underlying mechanisms.

Methods: Endothelium-intact and -denuded aortic rings were prepared from rats. The tension of the preparations was recorded isometrically with a force displacement transducer connected to a polygraph. The phosphorylation levels of ERK1/2 and myosin light chain (MLC) were analyzed using Western blotting assay.

Results: Application of brazilin (10-100 μmol/L) dose-dependently relaxed the NE- or high K(+)-induced sustained contraction of endothelium-intact aortic rings (the EC50 was 83.51±5.6 and 79.79±4.57 μmol/L, respectively). The vasorelaxant effect of brazilin was significantly attenuated by endothelium removal or by pre-incubation with L-NAME, methylene blue or indomethacin. In addition, pre-incubation with brazilin dose-dependently attenuated the vasoconstriction induced by KCl, NE or Ang II. Pre-incubation with brazilin also markedly suppressed the high K(+)-induced extracellular Ca(2+) influx and NE-induced intracellular Ca(2+) release in endothelium-denuded aortic rings. Pre-incubation with brazilin dose-dependently inhibited the NE-stimulated phosphorylation of ERK1/2 and MLC in both endothelium-intact and -denuded aortic rings.

Conclusion: Brazilin induces relaxation in rat aortic rings via both endothelium-dependent and -independent ways as well as inhibiting NE-stimulated phosphorylation of ERK1/2 and MLC. Brazilin also attenuates vasoconstriction via blocking voltage- and receptor-operated Ca(2+) channels.

Show MeSH
Related in: MedlinePlus