Nanosecond, high-intensity electric pulses have been reported to open rectifying pores in biological cell membranes. The present goal is to qualitatively understand and analyze the experimental current-voltage (I-V) data. Here, nanopore transport is probed using a numerical method and on the basis of an analytical model. Our results show that geometric asymmetry in the nanopore would not yield asymmetry in the I-V characteristics. However, positive surface charge lining the pore could produce characteristics that compare well with data from patch-clamp measurements, and a value of ∼0.02C/m2 is predicted from the numerical calculations.