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The newer monoamine oxidase inhibitors have clinical actions in hypertension and angina pectoris similar to those of iproniazid but appear to produce less frequent side effects. Some of the side effects suggest that in addition to amine oxidase inhibition, they may also have a ganglionic blocking action. The amine oxidase inhibitors are effective and useful in the clinical management of refractory cases of angina pectoris even though they may not alter the electrocardiogram significantly. Since the relief of chest pain also is accompanied frequently by a sense of well-being, cautioning the patient against over-exertion is advisable. Some of the amine oxidase inhibitors are also worthy of a trial in resistant cases of hypertension. However, they should be employed cautiously in these selected cases since their long term effects, even in moderate dosage, on liver and cardiac function are not known.

Storage and release of catecholamines in the isolated heart and the heart in vivo were investigated. The addition of DOPA to the perfusion fluid of a heart-lung preparation markedly increased the catecholamine concentration of the isolated heart. In vivo , the combination of iproniazid and DOPA had the same effect. Iproniazid alone failed to influence myocardial amine concentration. Nicotine raised the catecholamine concentration in heart muscle; electrically induced tachycardia failed to lower the catecholamine content of the heart in vivo ; reserpine caused a marked reduction. The reasons for the absence of a pharmacologic effect of the stored catecholamines are discussed.