[Na-K ionic pump and spike adaptation in the slowly and rapidly adapting stretch receptor neuron of the crayfish Orconectes limosus (RAF.)].
A very important cause of the spike adaptation in the slowly adapting stretch receptor neuron (SN1) is the Na-K ionic pump. An increasing inhibition of the ionic pump, produced by gradual reduction of the external K+-concentration or application of rising doses of ouabain, is correlated with an adequate diminution of frequency decay. But even high concentrations of ouabain (10(-3) -- 5 . 10(-3) M) can not completely abolish the spike adaptation. Immediately after the onset of a current step the impulse frequency still declines. In agreement with these findings the gain in the Bode diagram shows a maximum further on. The spike adaptation in the rapidly adapting neuron (SN2) can only in a smaller part be attributed to the action of the ionic pump. Application of ouabain causes in the SN2, contrary to SN1, only a low depolarization of the membrane potential. The decay of impulse frequency is considerably diminished but a long lasting nearly stationary discharge like in the SN1 can never be observed.
D000818:Animals; D003400:Astacoidea; D004558:Electric Stimulation; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D009126:Muscle Relaxation; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*
D007473:Ion Channels; D010042:Ouabain; D012964:Sodium; D011188:Potassium
Na-K-Ionenpumpe und Spike-Adaptation im langsam und schnell adaptierenden Dehnungsrezeptorneuron des Flusskrebses Orconectes limosus (RAF.).