Abstract
The modulatory actions of 5-hydroxytryptamine (5-HT) and octopamine (OA) were investigated in the opener nerve-muscle preparation of the crayfish, Astacus leptodactylus. Membrane resistance and resting potential were unaltered by 5-HT and OA at concentrations up to 2.5 X 10(−5) M; but EPSP-amplitudes were increased, up to 3-fold by OA and up to 18-fold by 5-HT. The lowest effective concentration was 2.5 X 10(−9) M; a maximal effect was produced at 2.5 X 10(−6) M. The effect was reversible only after prolonged washing. The enhancement of EPSPs by 5-HT or OA is due to an increased amplitude of the synaptic current; the current duration is not altered. The facilitation ratio (ratio of amplitudes of a pair of EPSPs) is not significantly affected by 5-HT or OA despite the often enormous increase of the absolute EPSP-amplitudes. The modulatory action also affects the excitation-contraction (e-c) coupling process: the effectiveness of e-c coupling was increased 7.4-fold by 5-HT (2.5 X 10(−6) M) and 18.7-fold by OA (5 X 10(−6) M). The threshold potential of e-c coupling was not affected.
Publisher
The Company of Biologists
Subject
Insect Science,Molecular Biology,Animal Science and Zoology,Aquatic Science,Physiology,Ecology, Evolution, Behavior and Systematics
Cited by
52 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献