The effect of various MAO-B inhibitors on rabbit arterial strip response to tyramine.

Studies on the response to tyramine of the rabbit pulmonal artery strip have revealed that several specific MAO-B inhibitors (TZ-650, J-580, AGN-1135, U-1424 MDL-72165 and Ro 16-6491) potentiated the responses in a dose-dependent manner, similarly as a semi-selective MAO-B inhibitor pargyline and a nonselective MAO inhibitor tranylcypromine did. Only (-)deprenyl inhibited the response. Thus the inhibition of noradrenaline-releasing effect of tyramine, a property favorable from the point of view of safety in clinical practice, is a specific feature of (-)deprenyl and not a more general characteristics of MAO-B inhibitors.