M. H. Abu Zarga

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.

Effects of Cirsiliol, a Flavone Isolated from Achillea fragrantissima, on rat isolated smooth muscle

AbstractThe effects of the flavone cirsiliol on rat isolated phenylephrine-precontracted proximal aorta, acetylcholine-pre-contracted trachea, urinary bladder, and uterus were studied. Cirsiliol (10−8-3×10−4M) caused concentration-dependent relaxation of the rat isolated phenylephrine-precontracted proximal aorta, acetylcholine-precontracted trachea, urinary bladder and inhibited the phasic contractions and the tone of the uterus. Cirsiliol (3×10−5, 1×10−4 and 3×10−4M) shifted to the right epinephrine concentration-effect curves on the proximal aorta and significantly inhibited the maximum contractions induced by epinephrine in this preparation. In Ca2+-free, depolarizing salt solution, cirsiliol (3×10−5, 1×10−4 and 3×10−4M) also shifted to the right CaCl2 concentration-effect curves on the proximal aorta and inhibited the maximum contractions induced by 3×10−2M CaCl2 whereas it had no effect on epinephrine-induced contractions in Ca2+-free salt solution on the same preparation. These observations suggest...

Effects of oblongine chloride, an alkaloid from Leontice leontopetalum on guinea-pig isolated smooth muscle and heart.

1. The effects of (-)oblongine chloride, a quaternary alkaloid from Leontice leontopetalum, on guinea-pig isolated ileal longitudinal segments, main pulmonary artery rings, spontaneously-beating atrium and isolated perfused heart were studied. 2. Oblongine chloride (3 x 10(-5)-10(-3) M) caused concentration-dependent relaxation of ileum, an effect which was not blocked by propranolol (10(-6) M) alone or in combination with prazosin (3 x 10(-8) M), or by indomethacin (10(-6) M), but was reduced by desensitization of the preparation by prior exposure to 3 x 10(-5) M ATP and, at high concentrations of oblongine, by a combination of propranolol and yohimbine (3 x 10(-6) M). 3. Oblongine chloride (10(-5)-3 x 10(-3) M) caused concentration-dependent relaxation of epinephrine-precontracted pulmonary artery. This effect was not affected by propranolol or by indomethacin but was significantly attenuated by pretreatment with 3 x 10(-5) M ATP and potentiated by pretreatment with quinacrine (10(-5) M). 4. Oblongine chloride (10(-5) M-3 x 10(-3) M) caused concentration-dependent increase in the contractility but did not affect the rate of the atrium. Similar effects were obtained with isolated perfused heart except that large concentrations of oblongine (10(-3), 3 x 10(-3) M) inhibited both contractility and rate of the heart. The inotropic effects of oblongine on the atrium were not blocked by propranolol or indomethacin but were significantly blocked by quinacrine.(ABSTRACT TRUNCATED AT 250 WORDS)