9.161 – Electrophysiology

Home work set 4 (sample figures)

 

Examination of the kinetic properties of AMPA and NMDA receptors

 

The kinetic steps of glutamate receptor activation following the release of transmitters can be summarized in the following general scheme. The set of equations can be used to simulate the process of glutamate receptor activation.

For NMDA receptor

Text Box:

 

 

For AMPA receptor

 

Text Box:

and R the glutamate receptor, A the concentration of transmitter, AR the receptor with single transmitter binding, A2R the receptor with two transmitter binding, and A2R* the receptor in open channel configuration. Therefore, the probability of channel opening after transmitter release Po will be determined by A2R*.

 

The kinetic rate constants for AMPA receptors are

The kinetic rate constants for NMDA receptors are

 

The concentration of glutamate in the synaptic cleft can be imitated by

where Amax is the peak concentration of transmitters. During the process of synaptic transmission, Amax can vary from 100 mM up to 3000 mM.

 

Solve above equations numerically using MATLAB and answer the following questions.

  1. What determines the decay phase of an EPSC, the profile of glutamate concentration or intrinsic properties of the channel? Does the decay phase of EPSCAMPA or EPSCNMDA receptor activation depend upon the glutamate concentration?
  2. Describe the behavior of AMPA vs NMDA receptors under repetitive activation. Can one increase AMPA receptor activation by repetitive release of transmitter? What about NMDA receptors?