www.neuron.yale.edu

first of all, merry christmas to everybody.

i'm in a part of the world where they do not celebrate christmas so work continues! I'm in the process of making a ion-dependent channel, a Na-dependent K channel. More specific, i have a system in which there are three currents, (i) Na channel, (ii) K channel and (iii) the Na-dependent K channel. The first two channels are fairly straightforward and work well. The third however, is not working as planned. The third channel is dependent on the current computed by the Na channel. However, with USEION i cannot access that current ("USEION na read ina" doesn't work).

My solution to this problem was to compute the complete Na current in the Na-dependent K channel as well, and use the computed ina (which is computed in that file, and hence accessible) for the gating of the K-component of that channel. I guess this works ok now (in spite of some unit-errors). Unfortunately, i'm trying a lot of different conductances for all channels, which means that i have to set the conductance for both the Na and the Na-component of the Na-dep K channel. The algorithm for trying different settings of these conductances cannot cope with this. Therefore, isn't there a "smarter" way to compute the Na-dep K channel in which i can simple read the ina?

Thanks, Ben

The best strategy is to address the problem head on. The problem is the inability of your K channel mechanism to discover the Na current. The cause is most likely an error of syntax, in which case there is no need to resort to idiosyncratic workarounds. Less likely but potentially more serious is a bug in NEURON that makes USEION not work properly; if this is the case, the bug should be fixed. To help resolve this issue, can you please send me
ted dot carnevale at yale dot edu
a zip file that contains only your mod files and just enough hoc (and ses) files to reproduce the symptom? Also, exactly what version of NEURON are you using?