Korean J Physiol Pharmacol.  2017 Nov;21(6):617-623. 10.4196/kjpp.2017.21.6.617.

Taurine relaxes human radial artery through potassium channel opening action

• Ulusoy KG
• Kaya E
• Karabacak
• Seyrek M
• Duvan I
• Yildirim V
• Yildiz O

• KMID: 2395256
• DOI: http://doi.org/10.4196/kjpp.2017.21.6.617

Abstract

The vascular actions and mechanisms of taurine were investigated in the isolated human radial artery (RA). RA rings were suspended in isolated organ baths and tension was recorded isometrically. First, a precontraction was achieved by adding potassium chloride (KCl, 45 mM) or serotonin (5-hydroxytryptamine, 5-HT, 30 µM) to organ baths. When the precontractions were stable, taurine (20, 40, 80 mM) was added cumulatively. Antagonistic effect of taurine on calcium chloride (10 µM to 10 mM)-induced contractions was investigated. Taurine-induced relaxations were also tested in the presence of the K⁺ channel inhibitors tetraethylammonium (1 mM), glibenclamide (10 µM) and 4-aminopyridine (1 mM). Taurine did not affect the basal tone but inhibited the contraction induced by 5-HT and KCl. Calcium chloride-induced contractions were significantly inhibited in the presence of taurine (20, 40, 80 mM) (p<0.05). The relaxation to taurine was inhibited by tetraethylammonium (p<0.05). However, glibenclamide and 4-aminopyridine did not affect taurine-induced relaxations. Present experiments show that taurine inhibits 5-HT and KCl-induced contractions in RA, and suggest that large conductance Ca²âº-activated K⁺ channels may be involved in taurine-induced relaxation of RA.

Keyword

Potassium Channel; Radial Artery; Taurine; Vasodilation

MeSH Terms

4-Aminopyridine
Baths
Calcium
Calcium Chloride
Glyburide
Humans*
Potassium Channels*
Potassium Chloride
Potassium*
Radial Artery*
Relaxation
Serotonin
Taurine*
Tetraethylammonium
Vasodilation
4-Aminopyridine
Calcium
Calcium Chloride
Glyburide
Potassium
Potassium Channels
Potassium Chloride
Serotonin
Taurine
Tetraethylammonium

Figure

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  Fig. 1 Original tracings showing vasorelaxations to taurine (20, 40, 80 mM) in KCl (45 mM)-precontracted human radial artery rings in the absence (control) and presence of tetraethylammonium (TEA, 1 mM).

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  Fig. 2 Effects of incubation with taurine (20, 40 or 80 mM) for 20 min on contractions induced by KCl (45 mM) in human radial artery rings (n=6). Each value represents mean±S.E.M. and it is calculated as the percentage of the first KCl (45 mM)-induced contraction in the same ring. Vertical bars represent S.E.M. *p<0.001 compared with control.

• 

  Fig. 3 Effects of 20 min incubation with taurine (20, 40, 80 mM) on contractions induced by 5-HT (30 µM) in human radial artery preparations (n=6). Each value represents mean±S.E.M. and it is calculated as the percentage of the first KCl (45 mM)-induced contraction in the same ring. Vertical bars represent S.E.M. *p<0.001, compared with control.

• 

  Fig. 4 Inhibitor effects of 20 min incubation with taurine (80 mM) on contractions induced by KCl (11, 22, 45, 68 mM) in human radial artery preparations (n=6). Each value represents mean±S.E.M. and it is calculated as the percentage of the first KCl (45 mM)-induced contraction in the same ring. Vertical bars represent S.E.M. *p<0.001, compared with corresponding control.

• 

  Fig. 5 Inhibitor effects of 20 min incubation with taurine (20, 40, 80 mM) on contractions induced by CaCl2 (10−5 to 10−2 M) in human radial artery preparations (n=6). Each value represents mean±S.E.M. and it is calculated as the percentage of the first KCl (45 mM)-induced contraction in the same ring. Vertical bars represent S.E.M. *p<0.001 compared with taurine (20, 40, 80 mM).

• 

  Fig. 6 Vasorelaxations to cumulative concentrations of taurine (20, 40, 80 mM) in human radial artery rings precontracted with 45 mM KCl in the presence of tetraethylammonium (TEA, 1 mM), 4-aminopyridine (4-AP, 1 mM), barium chloride (BaCl2, 30 µM) and glibenclamide (GLI, 10 µM). Each value represents mean±S.E.M. and it is calculated as the percentage of the first KCl (45 mM)-induced contraction in the same ring (n=7~11). Vertical bars represent S.E.M. *p<0.01, **p<0.001 compared with corresponding control.

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