Skip to main content
Log in

Endothelium-independent vasodilator effect of isocorynoxeine in vitro isolated from the hook of Uncaria rhynchophylla (Miquel)

  • Original Article
  • Published:
Naunyn-Schmiedeberg's Archives of Pharmacology Aims and scope Submit manuscript

Abstract

This study was designed to investigate the vasorelaxant effects and underlying mechanism of isocorynoxeine (ICN), one of the indole alkaloids from Uncaria hooks, on isolated mesenteric arteries in vitro. The myograph system was applied for isometric tension recording in the vascular rings. ICN relaxed both endothelium-intact and endothelium-denuded rat vascular rings precontracted with phenylephrine or KCl in a dose-dependent manner. Propranolol, tetraethylammonium, BaCl2, and glibenclamide had no influence on the vasodilator effect of ICN on phenylephrine-primed vascular rings, while 4-aminopyridine decreased the maximum relaxation. Furthermore, ICN produced a significant drop in maximum response in the PE log concentration-response curve without shifting to the right. In the Ca2+-free Kreb’s-Henseleit buffer, ICN inhibited the contraction in vascular rings evoked by PE, but not by KCl. The phasic contractions of segments in the Ca2+-free Kreb’s-Henseleit buffer induced by CaCl2 were restrained by ICN, while contractions elicited by caffeine displayed no differences. Furthermore, the phasic vasodilation of ICN was significantly lower than controls when pretreated with nifedipine and heparin. Both BAYK8644- and PE-evoked responses were significantly inhibited in the presence of 100 μM of ICN in human vascular smooth muscle cells loaded with the fluorescent Ca2+ indicator Fluo-4-AM. All these results suggest that ICN act in an endothelium-independent manner on the mesenteric artery. Its mechanisms of vasorelaxant action were produced by the inhibition of L-type calcium channel-mediated external Ca2+ influx and α1A-adrenoceptor-mediated intracellular Ca2+ release in vascular smooth muscle cells, and the participation of the Kv channel.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

References

Download references

Acknowledgements

We gratefully acknowledge the National Natural Science Foundation of China (No. 81673398) for financial support.

Author contribution statement

SW and TL conceived of or designed study. TL and KX performed research. TL and NJ analyzed data. ZH and DC contributed new reagents and analytical tools. TL wrote the paper. All authors read and approved the manuscript.

Funding

This study was funded by National Natural Science Foundation of China (No. 81673398).

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Sicen Wang.

Ethics declarations

Conflicts of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving animals were in accordance with the ethical standards of the Ethical Committee of Xi’an Jiaotong University.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Electronic supplementary material

Supplementary Fig 7

The LC/MS-IT-TOF MS spectra of ICN (GIF 8 kb)

High resolution Image (TIF 583 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Li, T., Xu, K., Che, D. et al. Endothelium-independent vasodilator effect of isocorynoxeine in vitro isolated from the hook of Uncaria rhynchophylla (Miquel). Naunyn-Schmiedeberg's Arch Pharmacol 391, 1285–1293 (2018). https://doi.org/10.1007/s00210-018-1536-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00210-018-1536-y

Keywords

Navigation