Abstract--Para-methoxyamphetamine (PMA) and 3, 4-methylene-dioxyamphetamine (MDA) both had potent stimulatory effects on mean arterial blood pressure and heart rate in the cat. These effects were antagonized by bretylium, a compound which blocks release of nore-pinephrine. The increases in heart rate were also antagonized by pro-pranolol and the blood pressure increases by phenoxybenzamine. PMA and MDA were nearly equipotent. In male albino mice, determination of 6 hr LDs0's indicated PMA to be most toxic although 24 hr LDs0's showed nearly equal toxicity. MDA had a potent hyperthermic effect in mice which was partially antagonized by bretylium and was blocked by haloperidol. The hyperthermic effect of PMA was not as pronounced and was followed by hypothermia.
