Endothelium-Independent Vasodilatory Effect of Sailuotong (SLT) on Rat Isolated Tail Artery

S Y Yeon; S W Seto; G H H Chan; M Low; H Kiat; N Wang; J Liu; D Chang

doi:10.1155/2020/8125805

Endothelium-Independent Vasodilatory Effect of Sailuotong (SLT) on Rat Isolated Tail Artery

Evid Based Complement Alternat Med. 2020 Sep 22:2020:8125805. doi: 10.1155/2020/8125805. eCollection 2020.

Authors

S Y Yeon¹, S W Seto^{1

2}, G H H Chan³, M Low¹, H Kiat^{4

5

6}, N Wang^{1

7}, J Liu^{1

8}, D Chang¹

Affiliations

¹ NICM Health Research Institute, Western Sydney University, Penrith, NSW 2751, Australia.
² Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
³ Hong Kong Community College, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
⁴ Faculty of Medicine, University of New South Wales, Kensington, NSW 2052, Australia.
⁵ School of Medicine, Western Sydney University, Penrith, NSW 2571, Australia.
⁶ Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2113, Australia.
⁷ Key Laboratory of Chinese Medicinal Formula of Anhui Province, Anhui University of Chinese Medicine, Hefei 230012, China.
⁸ Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, China.

Abstract

Background: Sailuotong (SLT) is a standardized three-herb formulation consisting of extracts of Panax ginseng, Ginkgo biloba, and Crocus sativus for the treatment of vascular dementia (VaD). Although SLT has been shown to increase cerebral blood flow, the direct effects of SLT on vascular reactivity have not been explored. This study aims to examine the vasodilatory effects of SLT and the underlying mechanisms in rat isolated tail artery.

Methods: Male (250-300 g) Wistar Kyoto (WKY) rat tail artery was isolated for isometric tension measurement. The effects of SLT on the influx of calcium through the cell membrane calcium channels were determined in Ca²⁺-free solution experiments.

Results: SLT (0.1-5,000 μg/ml) caused a concentration-dependent relaxation in rat isolated tail artery precontracted by phenylephrine. In the contraction experiments, SLT (500, 1,000, and 5,000 μg/mL) significantly inhibited phenylephrine (0.001 to 10 μM)- and KCl (10-80 mM)-induced contraction, in a concentration-dependent manner. In Ca²⁺-free solution, SLT (500, 1,000, and 5,000 μg/mL) markedly suppressed Ca²⁺-induced (0.001-3 mM) vasoconstriction in a concentration-dependent manner in both phenylephrine (10 μM) or KCl (80 mM) stimulated tail arteries. L-type calcium channel blocker nifedipine (10 μM) inhibited PE-induced contraction. Furthermore, SLT significantly reduced phenylephrine-induced transient vasoconstriction in the rat isolated tail artery.

Conclusion: SLT induces relaxation of rat isolated tail artery through endothelium-independent mechanisms. The SLT-induced vasodilatation appeared to be jointly meditated by blockages of extracellular Ca²⁺ influx via receptor-gated and voltage-gated Ca²⁺ channels and inhibition of the release of Ca²⁺ from the sarcoplasmic reticulum.