title: Alseis yucatanensis: a natural product from Belize that exhibits multiple mechanisms of vasorelaxation.
abstract: An aqueous extract of the bark of Alseis yucatanensis was studied to determine its mechanism of action in the relaxation of endothelium-denuded rat aortic tissues. The extract relaxed both norepinephrine (NE) and KCl-contracted vessels, with ED(50)'s of 0.12 and 1.73 mg/mL, respectively. In NE-contracted vessels, two phases of relaxation were evident which were separated in both time and dose range. At high concentrations, a rapid relaxation was seen that was due to the blocking of internal (ED(50)=0.49 mg/mL) and external (ED(50)=2.34 mg/mL) calcium channels. A second, slowly developing (i.e., long-term) relaxation to baseline was seen at lower concentrations. The time to complete relaxation was dose-dependent. This long-term response was not seen in KCl-contracted vessels, was prolonged by TEA, and could be reversed by the addition of KCl to the bath. These data suggest that the long-term relaxation is due to the opening of potassium channels.
authors.affiliation: Department of Biological Science, Plattsburgh State University, 101 Broad Street, Plattsburgh, NY 12901, USA. donald.slish@plattsburgh.edu
authors.forename: Donald F
authors.initials: DF
authors.lastname: Slish
authors.forename: Rosita
authors.initials: R
authors.lastname: Arvigo
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Balick
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001531:Belize; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019666:Rubiaceae / Q000737:chemistry*; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D010936:Plant Extracts; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents