minature inhibitor postsynaptic currents

r norman rsn_ at _comcast.net
Thu Sep 16 19:15:51 EST 2004


On Thu, 16 Sep 2004 23:59:35 GMT, BilZ0r
<BilZ0r at TAKETHISOUThotmail.com> wrote:

>r norman <rsn_ at _comcast.net> wrote in
>news:oj8kk055kltot3a30r5395vdvq9bsrmguh at 4ax.com: 
>
>>>Thank you very much, so minature potentiatals would always be of the
>>>same size? So agonists at presynaptic receptors which inhibit calcium 
>>>channels, would effect the rate of minature potentials, but not there 
>>>amplitude, while the same agonist would effect the rate and amplitude
>>>of spontaneous potentials?
>> 
>> Minis are often of a consistent size, but not always.  Depending on
>> just where you are recording, they can vary for several reasons:
>> different quantities of transmitter release or different distances
>> from the recording site. They do show variation, though, sometimes
>> with substantial variance even though there is a single peak in the
>> amplitude histogram. 
>> 
>> Agents that influence vesicle release tend to alter the frequency but
>> not the amplitude.  Agents that influence postsynaptic response tend
>> to alter the amplitude but not the frequency.  
>> 
>> I don't understand the last half of your last statement.  You seem to
>> make a distinction between miniature potentials and spontaneous
>> potentials when I just told you they were the same thing.
>> 
>
>Oh... I thought spontaneous potentials were the result of sponateous 
>firing of a neuron, as against evoked firing.

No, it is the spontaneous release of a vesicle, as against release
evoked by presynaptic depolarization and consequent Ca++ events.





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