Effect of naringin and naringenin on contractions induced by noradrenaline in rat vas deferens--I. Evidence for postsynaptic alpha-2 adrenergic receptor.
1. Naringin at all doses (2 x 10(-6), 5 x 10(-7), and 1 x 10(-7) M) significantly increased contractions induced by noradrenaline in rat vas deferens but the increments of maximal contraction were not concentration-dependent. 2. In a medium containing 1 x 10(-6) M yohimbine (a selective blocker of alpha 2-adrenoceptor) and naringin, the curve constructed with noradrenaline decreased below the control curve. 3. Naringenin (aglycone of naringin) (2 x 10(-6) and 1 x 10(-7) M) increased the contractile effect of noradrenaline and the maximal effect evoked was related to the maximal dose of naringenin. 4. The alpha 2 antagonism produced by yohimbine in the naringenin-noradrenaline association were retained at two doses of naringenin tested and we noticed a similar behaviour when we used clonidine-noradrenaline.
Laboratory of Pharmacodinamy, Faculty of Pharmacy, University of Seville, Spain.
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Herrera
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Marhuenda
D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D044950:Flavanones; D005419:Flavonoids / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000294:innervation; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D013569:Synapses / Q000187:drug effects*; D014649:Vas Deferens / Q000187:drug effects / Q000294:innervation; D015016:Yohimbine / Q000494:pharmacology
D044950:Flavanones; D005419:Flavonoids; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; C005273:naringenin; D003000:Clonidine; C005274:naringin; D009638:Norepinephrine