. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Vol. 83, No. 2 October, 1942 THE BIOLOGICAL BULLETIN PUBLISHED BY THE MARINE BIOLOGICAL LABORATORY AN ANALYSIS OF THE ACTION OF ACETYLCHOLINE ON HEARTS, PARTICULARLY IN ARTHROPODS C. LADD PROSSER (From the University of Illinois, Urbana, and the Marine Biological Laboratory, Woods Hole) Two organic compounds have been shown to be liberated as media- tors at nerve endings, adrenin-like sympathin and acetylcholine. The distribution of these substances throughout the animal kingdom is nearly universal. Adrenalin seems to be exc
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Vol. 83, No. 2 October, 1942 THE BIOLOGICAL BULLETIN PUBLISHED BY THE MARINE BIOLOGICAL LABORATORY AN ANALYSIS OF THE ACTION OF ACETYLCHOLINE ON HEARTS, PARTICULARLY IN ARTHROPODS C. LADD PROSSER (From the University of Illinois, Urbana, and the Marine Biological Laboratory, Woods Hole) Two organic compounds have been shown to be liberated as media- tors at nerve endings, adrenin-like sympathin and acetylcholine. The distribution of these substances throughout the animal kingdom is nearly universal. Adrenalin seems to be excitatory on all adult hearts although many molluscan hearts are relatively insensitive to it. Acetylcholine has an inhibitory action on the systemic hearts of adult vertebrates and of molluscs; acetylcholine has no action on the hearts of early Fundulus embryos; it has an accelerating action on the hearts of decapod Crustacea, of Limulus, the grasshopper Melanoplus, and of the annelids Arenicola and Lumbricus; (see Table II for references). It might be possible to explain these three types of action of acetyl- choline if a wide variety of hearts was compared with respect to drug effects and histological characteristics. Baylor (1942) has recently found acetylcholine to inhibit the Daphnia heart. This indicates that acceleration is not characteristic of all arthropods and it becomes important to know which groups show acceleration, which inhibition, and which no effect of acetylcholine. In establishing the physiological action of a the effects must be reversible and a threshold concentration must be demonstrable. These two criteria have been adhered to in the following experiments. The mere fact that acetylcholine acts in a given manner on an effector does not imply that the nerves supplying that effector liberate acetyl- choline. Mediation by a substance can be proved only when that substance is obtained in a perfusate and when potentiating and inhibit- ing drugs are comb
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
