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The Alpha-Adrenoceptor Blocking Properties of Cryptolepine on the Rat Isolated Vas Deferens
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1980
Year
Molecular PharmacologyInduced ContractionsPsychoactive DrugPharmacological StudyMedicinePhysiologyObserved PotentiationAlpha-adrenoceptor Blocking PropertiesNeuroendocrine MechanismNeuropharmacologyExperimental PharmacologyPharmacotherapyNeurosciencePotentiatory EffectNervous SystemPharmacologyNeuropeptides
Cryptolepine, an alkaloid of Crypto-lepsis sanguinolenta (Lindl. Schlecter) is an antagonist of noradrenaline on the rat isolated vas deferens. It is of about the same potency as phentolamine (pA2 of phentolamine = 7.5 ± 0.40, pA2 of cryptolepine = 6.6 ± 0.35). We here report a potentiatory effect of small doses of cryptolepine (3.0 × 10-7-10-6M) on the effect of noradrenaline, an effect which has not been obtained with phentolamine, and methoxamine - induced contractions of the vas deferens. Cocaine antagonised the potentiatory effects of small doses of cryptolepine. Inhibition of neuronal uptake is suggested as the probable mechanism for the observed potentiation.