Looks like the k-a channel, modified from b_a.mod in safronov et al. (2000), model no. 62266, but with gkbar set to zero and slightly different parameters for kinetic equations. Note: in the paper it says that the ka current was negligible and so not included in the model at all. Experimental results and model, largely from ancestor model. The animal model info here is from experimental methods.
Model has temperature dependence, with original kinetics at 6.3 deg C.