Antispasmodic and blood pressure lowering effects of Valeriana wallichii are mediated through K+ channel activation.
Crude extract of Valeriana wallichii rhizome (Vw.Cr) and its fractions were studied for possible antispasmodic and blood pressure lowering activities to rationalize some of the folkloric uses. In rabbit jejunum preparations, Vw.Cr (0.1-3.0 mg/mL) caused relaxation of spontaneous contractions. When tested against high K(+) (80 mM)-induced contractions it produced weak inhibitory effect, while caused complete relaxation of the contractions induced by low K(+) (20 mM). In the presence of glibenclamide (3 microM), the inhibitory effect of low K(+) was shifted to the right, similar to that produced by cromakalim while, verapamil caused no differentiation in its inhibitory effect against low and high K(+)-induced contractions. In guinea pig ileum, the plant extract produced similar results as in rabbit jejunum. Intravenous administration of Vw.Cr, produced fall in arterial blood pressure in normotensive anaesthetized rats and this effect was partially blocked by glibenclamide. In rabbit aortic preparations, plant extract also caused a selective and glibenclamide-sensitive relaxation of low K(+) (20 mM)-induced contractions. Activity-directed fractionation studies revealed that the observed activity was distributed both in the chloroform and aqueous fractions. These results indicate that the antispasmodic and hypotensive effects of Valeriana wallichii are mediated possibly through K(ATP) channel activation, which justify its use in gastrointestinal and cardiovascular disorders.
Gilani
Anwar H
AH
Department of Biological and Biomedical Sciences, The Aga Khan University Medical College, Karachi 74800, Pakistan. anwar.gilani@aku.edu
Khan
Arif-ullah
AU
Jabeen
Qaiser
Q
Subhan
Fazal
F
Ghafar
Rukhsana
R
D000818:Animals; D019806:Cromakalim / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D006168:Guinea Pigs; D007004:Hypoglycemic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D007583:Jejunum / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D010276:Parasympatholytics / Q000302:isolation & purification / Q000494:pharmacology*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry; D015221:Potassium Channels / Q000819:agonists* / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D014632:Valerian / Q000737:chemistry*; D014655:Vascular Resistance / Q000187:drug effects
D007004:Hypoglycemic Agents; D010276:Parasympatholytics; D010936:Plant Extracts; D015221:Potassium Channels; D019806:Cromakalim; D005905:Glyburide