Actions of Ya-hom, a herbal drug combination, on isolated rat aortic ring and atrial contractions |
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Authors: | W Suvitayavat S Tunlert SS Thirawarapan C Kitpati N Bunyapraphatsara |
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Institution: | Department of Physiology, Faculty of Pharmacy, Mahidol University, 447 Sri-ayuthaya Road, Bangkok 10400, Thailand. pyvsv@mahidol.ac.th |
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Abstract: | The effect of the Thai popular medicine Ya-hom on cardiovascular function was studied in isolated rat aortic ring and atrium by comparison with norepinephrine (NE). Water extraction of Ya-hom at concentrations of 0.83, 1.67, 8.33 and 16.67 mg/ml stimulated aortic ring contraction dose-dependently. The maximum contraction, at 16.67 mg/ml, was about 14% that of NE. This stimulatory effect of Ya-hom was inhibited partially by phentolamine, which indicated that the effect of Ya-hom was partially dependent on the alpha receptor, similar to NE. Administration of Ya-hom with NR decreased the force of aortic ring contraction as compared to the effect of NE alone, indicating that Ya-hom may have a partial alpha-agonist activity. Ya-hom at concentrations of 1.67, 8.33 and 16.67 mg/ml showed a dose-dependent, positive inotropic and negative chronotropic effects. Ya-hom increased the force of isolated atrial contraction with a slow onset and prolonged action. In contrast to norephinephrine, which acted on beta1 receptor, causing positive inotropic and chronotropic effects, propranolol did not alter the effect of Ya-hom on the atrial contraction. This shows that the action of Ya-hom on atrial contraction does not involve beta receptor. |
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Keywords: | Ya-hom Aortic ring Rat atrium Cardiovascular effects |
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