The BKCa channel blocker penitrem-A does not impair the SKA-31-induced inhibition of myogenic tone. The representative tracing in panel A shows vasodilatory responses to 3 μM SKA-31, 10 μM SNP, 20 μM NS1619 and 5 μM pinacidil in a myogenically active cremaster artery under control conditions and following exposure to 2 μM penitrem-A, as indicated by the horizontal bar beneath the tracing. The washout (W/O) of penitrem-A is also marked by a horizontal bar. The tracing in panel B depicts the effect of penitrem-A treatment on the inhibition of myogenic tone by the same set of agents in a middle cerebral artery. The summary data presented in panels C and D display the degree of inhibition of developed myogenic tone by SKA-31, SNP, NS1619 and pinacidil in the absence and presence of penitrem-A treatment in cremaster (panel C, n = 6) and middle cerebral arteries (panel D, n = 4). Data are expressed as means ± SEM. The asterisk (*) indicates a statistically significant difference in the magnitude of inhibition compared with control condition, as determined by an unpaired Student’s t-test.