Figure 2.

SKA-31 and ACh-induced inhibition of myogenic tone are largely prevented in the presence of UCL1684 + TRAM-34, blockers of KCa2.3 and KCa3.1 channels, respectively. Panel A shows a representative tracing of vasodilatory responses evoked by SKA-31 and ACh in a cremaster artery in the absence and presence of 0.5 μM UCL1684 + 1 μM TRAM-34. Following drug washout, the vessel was exposed to Kreb’s solution containing 2 mM EGTA and no added CaCl₂ to determine the maximal passive diameter. The addition of individual agents to the vessel chamber is indicated by the horizontal bars placed above and below the tracing. Panel B shows a parallel experiment carried out using a middle cerebral artery. Note that the observed inhibitory responses to ACh and SKA-31 were unaffected by the order of drug application during the experiment. The histogram in panel C quantifies the effects of UCL1684 + TRAM-34 treatment on the SKA-31 and ACh-induced inhibition of myogenic tone in cremaster and middle cerebral arteries. The asterisk (*) indicates a statistically significant difference in magnitude compared with the control response observed in the absence of KCa channel blockers, as determined by one-way ANOVA and a Tukey’s post-hoc test, P < 0.05.