SUR1-TRPM4 channel activation and phasic secretion of MMP-9 induced by tPA in brain endothelial cells
Fig 4
SUR1-TRPM4 channel opening by tPA requires Ca2+ influx via TRPC3.
A: Macroscopic currents during 200-ms step pulses (#1,3,5) and ramp pulses (–100 to +100 mV; 4 mV/msec) (#2,4), induced by recombinant tPA (rtPA) in activated murine BEC, recorded initially using extracellular solution with 1.8 mM Ca2+, and after switching to extracellular solution containing 0 mM Ca2+; right: illustrative currents during ramp pulses after addition of rtPA, before and after switch to 0 Ca2+; the difference current is also shown (thick line). B: rtPA-induced current in activated BEC was not blocked by ruthenium red (RR), but was blocked by Gd+3 and Pyr3; illustrative currents during ramp pulses after addition of rtPA, before and after Gd+3 or Pyr3 are also shown; bar graph: rtPA-induced currents in activated BEC in the presence of 1.8 mM Ca2+, 0 mM Ca2+; 1.8 mM Ca2+ plus RR or SKF-96365 or Pyr3 or Gd3+; cells/condition for each bar: 25, 7, 5, 7, 5, 7. C: Change in intracellular Ca2+ concentration (ΔF/F0) induced by rtPA in activated but not in non-activated (Ctr) BEC; the rtPA-induced increase in Ca2+ was blocked by pretreatment with SKF-96365 but not RR; bar graph: mean change at 10–12 minutes in intracellular Ca2+ concentration induced by rtPA in non-activated and activated BEC, in the presence of RR; SKF-96365; Gd3+; cells/condition for each bar: 10, 8, 10, 10, 10; ***, P<0.001.