Browsing by Author "Alemayehu, Tadesse"

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    Ex vivo vasodilatory activity of aqueous crude extract of Thymus schimperi leaves in isolated thoracic aorta of Guinea Pigs
    (Addis Ababa Universty, 2018-04) Alemayehu, Tadesse; Makonnen, Eyasu (PhD, Professor)
    Ex vivo vasodilatory activity of aqueous crude extract of Thymus schimperi leaves in isolated thoracic aorta of Guinea Pigs Tadesse Alemayehu Addis Ababa University, 2018 Hypertension remains a major health problem globally because of its impact on mortality and morbidity. It is defined as a persistent increase of systemic blood pressure. Blood pressure is created by the force of blood pushing against the walls of blood vessels as it is pumped by the heart. It is a multiplication product of cardiac output and peripheral vascular resistance. The goal of any antihypertensive therapy is to bring a reduction in either or both of these parameters, preferably peripheral vascular resistance. T. schimperi is one of the medicinal plants used in Ethiopia for treatment of hypertension and other diseases. But it lacks apposite pharmacological investigation for its vasodilatory effect. Thus, the aim of this study was to evaluate in vitro vasodilatory effects of aqueous crude extract of T. schimperi leaves in isolated thoracic aorta of guinea pigs using different contracting agents such as potassium chloride, epinephrine, methyline blue, glibenclamide, acetylcholine and histamine. Furthermore, the possible mechanism (s) of relaxation was also assessed. In the study guinea pig was sacrificed by gentle cervical dislocation and the thoracic aorta ring was removed, cut spirally and mounted in an organ bath containing 37oC maintained Kreb’s Henseleit physiological solution aerated with 95% O2 and 5% CO2 for experiment. The extract showed a relaxation effect in isolated thoracic aorta of guinea pigs pre-contracted by potassium chloride, epinephrine, glibenclamide, acetylcholine and histamine in dose dependent manner. But the extract failed to show significant relaxation effect of aorta pre-contracted by methyline blue on intact endothelium as compared to potassium chloride (intact and denuded endothelium), epinephrine, glibenclamide, acetylcholine and histamine (P<0.001). High doses of AQ crude extract have shown substantial vasodilatory activity against HIST and Ach-induced contractions of guinea pig thoracic aorta on denuded endothelium. In conclusion , the mechanisms of action of the extracts may be through blockage of both receptor-operated and L-type voltage dependent Ca2+ channels, activation of ATP-sensitive potassium channel, blockage of H1 and M3 receptors.