COMPARATIVE PHYSIOLOGICAL ACTIONS OF PHENYL-, THIENYL- AND FURYLISOPROPYLAMINES

¹ From the Pharmacological Laboratory, University of California Medical School, San Francisco, and the William G. Kerckhoff Laboratories of the Biological Sciences, California Institute of Technology, Pasadena

1. In dogs under ether or pentobarbital anesthesia, phenyl- and thienyl-isopropylamines injected intravenously induce pressor effects very closely similar as to intensity and duration. About three times as much furyl-isopropylamine is required to produce an equally intense pressor response, and a preceding depressor effect, which can be antagonized by a proper mol ratio of atropine, may occur.

2. On isolated rabbit intestinal strips, these three isopropylamines in minimally active concentrations induce an increase in tone that may be prevented by pretreatment with equal molal concentrations of atropine. With greater concentrations, all three compounds act to decrease tone, but the range of dosage in which furyl-isopropylamine acts only to increase tone is much greater than for phenyl- or thienyl-isopropylamine.

3. Phenyl- and thienyl-isopropylamines injected intraperitoneally into mice in nearly lethal dosages are more active motor stimulants than furyl-isopropylamine, and the thienyl compound has a shorter duration of action than phenisopropylamine.

4. Thienylisopropylamine injected intraperitoneally into mice is slightly less toxic than the phenyl compound, and furylisopropylamine is but about one-fourth as toxic as the other two compounds.

5. Orally administered to man, phenisopropylamine is very considerably more active as a circulatory stimulant and as a central nervous system stimulant, though these two activities appear unrelated.