Figure 4.

Time course of the inhibitory effects of 5-HT (1 µM, top panel) and H₂O₂ (100 µM, middle panel) on iberiotoxin-sensitive, large-conductance Ca²⁺-activated K⁺ (BK_Ca) amplitude of single basilar artery myocytes of SHR and WKY rats. The BK_Ca current was elicited using a train-pulse protocol with a test potential of +60 mV (500 ms pulse duration) from a holding potential of −60 mV at 0.03 Hz. (Bottom panel): summary of the macroscopic BK_Ca current amplitude recorded [peak BK_Ca current (pA·pF⁻¹) recorded at +60 mV from a holding potential of −60 mV for 500 ms duration at 0.0333 Hz] in response to 5-HT (1 µM) challenge in the absence or presence of different agents [citalopram, clorgyline, PEG-catalase and reduced glutathione (GSH)]. Mean ± SEM are indicated by columns and vertical bars respectively (*P < 0.05 and **P < 0.01). 5-HT, 5-hydroxytryptamine; PEG-catalase, polyethylene glycol-catalase; SHR, spontaneously hypertensive rats; WKY, Wistar-Kyoto rats.