Effects of cirsiliol, a flavone isolated from Achillea fragrantissima, on rat isolated ileum.
1. In concentrations from 10(-8) M to 3 x 10(-4) M, cirsiliol caused concentration-dependent relaxation of rat isolated ileum. 2. Phentolamine (10(-6) M) or phentolamine and propranolol (10(-6) M) had no significant effects on the concentration-effect curves or on the EC50 of cirsiliol on the ileum. 3. Cirsiliol shifted to the right the acetylcholine (Ach) concentration-effect curves on ileum and significantly inhibited the maximum contractions induced by Ach. 4. In Ca(2+)-free, depolarizing solution, cirsiliol shifted to the right the CaCl2 concentration-effect curves and inhibited the maximum contractions induced by CaCl2 on ileum. 5. Large concentrations (10(-4) M, 3 x 10(-4) M) of cirsiliol induced relaxation followed by contraction of the ileal segments incubated in Ca(2+)-free solution. 6. In Ca(2+)-free solution, cirsiliol (10(-4) M, 3 x 10(-4) M) caused concentration-dependent potentiation of the ileal contractions induced by 3 x 10(-3) M Ach when the latter was added 2-3 min after cirsiliol. When Ach was added 15-20 min after cirsiliol, the latter compound inhibited the Ach-induced contractions. 7. These observations suggest that cirsiliol inhibits Ca2+ influx but stimulates Ca2+ release from intracellular stores. Furthermore, they suggest that cirsiliol utilizes the same Ca2+ source used by acetylcholine in Ca(2+)-free solution.
Mustafa
E H
EH
Department of Biological Sciences, Faculty of Science, University of Jordan, Amman.
Abu Zarga
M
M
Abdalla
S
S
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D002122:Calcium Chloride / Q000494:pharmacology; D005260:Female; D047309:Flavones; D005419:Flavonoids / Q000494:pharmacology*; D007082:Ileum / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D010946:Plants, Medicinal / Q000737:chemistry*; D051381:Rats
D047309:Flavones; D005419:Flavonoids; C039824:cirsiliol; D002122:Calcium Chloride; D000109:Acetylcholine; D002118:Calcium