Many stages in the transportation of membrane proteins rely on the actin and/or microtubule based cytoskeletons. This is particularly well established for transport between the ER and Golgi, and in transport between the surface membrane and cytoplasmic organelles. Little is known, however, regarding the specific machineries utilized by the various cardiac potassium channels. Here we examine the effects of disruption of microtubules or of the dynein-dynactin retrograde motor complex on the functional expression of several potassium channels. Exposure of rat ventricular myocytes to the microtubule depolymerising agent nocodazole increases the magnitude of the transient outward current (I_TO) and decreases the inward rectifying (I_K1) current, resulting in a decrease in action potential duration. In heterologous expression systems, nocodazole treatment leads to changes in surface expression of several channels, and disruption of dynein motor function by p50 overexpression leads to time-dependent changes in expression in a subset of these. Thus, it is likely that different channels utilize different pathways in moving from the ER through the Golgi and on to the surface, as well as in post-internalization trafficking from the surface.