title: Actions of Ya-hom, a herbal drug combination, on isolated rat aortic ring and atrial contractions.
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.
authors.affiliation: Department of Physiology, Faculty of Pharmacy, Mahidol University, 447 Sri-ayuthaya Road, Bangkok 10400, Thailand. pyvsv@mahidol.ac.th
authors.forename: W
authors.initials: W
authors.lastname: Suvitayavat
authors.forename: S
authors.initials: S
authors.lastname: Tunlert
authors.forename: S S
authors.initials: SS
authors.lastname: Thirawarapan
authors.forename: C
authors.initials: C
authors.lastname: Kitpati
authors.forename: N
authors.initials: N
authors.lastname: Bunyapraphatsara
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D002316:Cardiotonic Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D006325:Heart Atria / Q000187:drug effects; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D010946:Plants, Medicinal; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002316:Cardiotonic Agents; D010936:Plant Extracts