Effects of carbon dioxide on extracellular potassium accumulation and volume in isolated frog spinal cord

1988 ◽  
Vol 412 (1-2) ◽  
pp. 183-187 ◽  
Author(s):  
Eva Syková ◽  
R. K. Orkand ◽  
A. Chvátal ◽  
I. Hájek ◽  
N. Kříž
Keyword(s):  
Carbon Dioxide ◽  
Spinal Cord ◽  
Extracellular Potassium ◽  
Potassium Accumulation ◽  
Frog Spinal Cord

scholarly journals Primary afferent activity, putative excitatory transmitters and extracellular potassium levels in frog spinal cord.

1988 ◽  
Vol 397 (1) ◽  
pp. 291-306 ◽  
Author(s):  
R A Davidoff ◽  
J C Hackman ◽  
A M Holohean ◽  
J L Vega ◽  
D X Zhang
Keyword(s):  
Spinal Cord ◽  
Extracellular Potassium ◽  
Afferent Activity ◽  
Primary Afferent ◽  
Frog Spinal Cord

Habituation of a monosynaptic response in frog spinal cord: evidence for a presynaptic mechanism

1976 ◽  
Vol 39 (4) ◽  
pp. 661-666 ◽  
Author(s):  
P. B. Farel ◽  
R. F. Thompson
Keyword(s):  
Spinal Cord ◽  
Rana Catesbeiana ◽  
Membrane Conductance ◽  
Resting Membrane Potential ◽  
Extracellular Potassium ◽  
Initial Value ◽  
Lateral Column ◽  
Frog Spinal Cord ◽  
Before And After ◽  
Stimulation Of

1. Using the isolated spinal cord of bullfrogs (Rana catesbeiana), intracellular correlates of habituation-like depression of the monosynaptic response elicited in motoneurons by lateral column (LC) stimulation were investigated. The following properties of the motoneuron were compared before and after response depression produced by stimulation of the LC at 0.5/s: resting membrane potential, membrane conductance, critical firing level, and rheobasic current. No alteration was found in any of these parameters. 2. To determine whether transmitter release mechanisms were changing over trials, the LC was stimulated with pairs of stimuli separated by 6 ms presented at 0.5/s. While the amplitude of the first EPSP declined (74% of initial value), the amplitude of the second EPSP increased (111% of initial value). Facilitation ratios thus increased. 3. The following conclusions can thus be drawn: 1) habituation involves a process intrinsic to the LC-motoneuron synapse; 2) habituation is not totally mediated by receptor desensitization; 3) habituation is not mediated by a mechanism extrinsic to the LC-motoneuron synapse that depolarizes terminal endings, e.g., presynaptic inhibition or accumulation of extracellular potassium; 4) habituation is not produced by transmitter depletion. Any of these possibilities has as a necessary consequence that facilitiation ratios remain unchanged. 4. Possible mechanisms that could mediate habituation are: 1) alterations in mobilization and/or release of transmitter; 2) decreased probability of invasion of terminal branches of the presynaptic fiber by the action potential.

Sign in / Sign up

Export Citation Format

Share Document