Voltage-dependent potassium (Kv) channels play an important functional role in small arteries. The hypothesis was tested that Kva2 subunits contribute to the Kv current in Wistar rat posterior cerebral artery smooth muscle cells. The conventional whole-cell patch-clamp technique was employed. Stromatoxin, a specific inhibitor of Kva2 subunits, inhibited the Kv current in a concentration-dependent manner with an ED₅₀ of 36 nM and a maximum effect of 61.2%. Stromatoxin at 100 nM did not affect the voltage-dependence of activation of the Kv current (potential of half-maximal activation: -6.2±2.3 mV and -4.4±1.9 mV (n=10) in the presence and absence of stromatoxin). In contrast, stromatoxin altered the voltage-dependence of inactivation (potential of half maximal inactivation: -45.1±2.5 mV and -37.9±1.4 mV (n=10; p<0.05) in the presence and absence of stromatoxin) but did not affect the recovery from inactivation (time constant: 2.12±0.20 sec and 2.14±0.24 sec (n=10) in the presence and absence of stromatoxin). Thus, the data show that a stromatoxin-sensitive current, most probably carried by Kva2 subunits, contributes considerably to the Kv current of smooth muscle cells isolated from Wistar rat posterior cerebral arteries.