Figure 3.

T-type voltage-dependent Ca²⁺ channels (T-type Ca_v) are involved in the endothelial cell depolarization evoked by the Panx-1 channel blockade. (a) Representative recordings of the changes in endothelial cell membrane potential evoked by 1 mM probenecid in control conditions or after removing Ca²⁺ ions from the buffer solution (Ca²⁺-free solution plus 2 mM EGTA). Note that the absence of extracellular Ca²⁺ ions unmasked two components: an initial peak and a Ca²⁺-dependent plateau phase. Treatment with the Ca²⁺-free solution was initiated 5 min before probenecid application. (b) Analysis of the peak and plateau phase of the depolarization evoked by probenecid in control conditions and during the treatment with a Ca²⁺-free solution, 100 μM mibefradil (Mb), or 10 μM Ni²⁺. (c, d) Representative images (c) and quantitative analysis (d) of the changes in [Ca²⁺]_i observed in response to the Panx-1 channel blockade with 60 μM ¹⁰Panx in primary cultures of endothelial cells. Note that tetrodotoxin (TTX, 300 nM) and Ni²⁺ abolished the increase in [Ca²⁺]_i activated by ¹⁰Panx. Values are means ± SEM. ^∗P < 0.05 vs. the peak by paired Student's t-test. ^†P < 0.05 vs. the control by one-way ANOVA plus the Newman-Keuls post hoc test.