Stereospecificity of Monoamine Oxidase Inhibitors

Pretreatment with two doses of reserpine (each 0.1 mg/kg, intraperitoneally) sensitizes the heart to the positive chronotropic action of norepinephrine and reduces the response to stimulation of the accelerans nerve. Ganglionic transmission remains unaffected. The results indicate that the presence of certain stores of peripheral sympathetic transmitter is essential for the production of tachycardia by stimulation of the accelerans nerve. Recent experiments (1) show that reserpine is capable of causing a tachycardia in the heart-lung preparation of the dog by liberation of norepinephrine from its stores in the heart. Pretreatment of the dogs with reserpine prior to the isolation of the heart, by depletion of the stores of norepinephrine, prevented the positive chronotropic response of the heart-lung preparation to the challenging dose of reserpine. A dose of 0.1 mg/kg injected intraperitoneally 24 hours before the heart-lung preparation was set up was found to suffice for the pretreatment (2). Other experimental evidence indicates that pretreatment with reserpine abolishes the stimulant action of nicotine on isolated rabbit atria (3); in this preparation nicotine acts presumably on ganglion cells or chromaffine tissue situated in the heart wall, or on both, and thus liberates sympathin. Reserpine has also been found to reduce the norepinephrine content of sympathetic ganglion cells (4). The experiments described in this report (5) were undertaken in order to 901 on N ovem er 1, 2017 http://sce.sciencem agorg/ D ow nladed fom Stereospecificity of Monoamine Oxidase Inhibitors A. PLETSCHER and K. F. GEY DOI: 10.1126/science.128.3329.900 (3329), 900-901. 128 Science ARTICLE TOOLS http://science.sciencemag.org/content/128/3329/900