Desensitization of Gamma Aminobutyric Acid (GABA) Receptors in Muscle Fibers of the Crab Cancer borealis |
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| Authors: | Ren Epstein and Harry Grundfest |
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| Institution: | From the Laboratory of Neurophysiology, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York 10032, and the Marine Biological Laboratory, Woods Hole, Massachusetts 02543. |
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| Abstract: | Carcinus muscle fibers respond to γ-aminobutyric acid (GABA) with a conductance increase that subsides rather rapidly. In the larger fibers which have low input resistance the decrease may disappear within 2 min. The inhibition of the excitatory postsynaptic potentials (EPSP's) by GABA nevertheless persists as long as the drug is applied. The subsidence of the increased conductance indicates that the membrane of the inhibitory synapses has become desensitized to GABA. The persistence of inhibition of the EPSP's appears to be due to an action of the drug on the presynaptic terminals of the excitatory axons which reduces or blocks the secretory activity that releases the excitatory transmitter. |
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