Skip to main content
. 2020 Jul 15;18(7):e3000750. doi: 10.1371/journal.pbio.3000750

Fig 5. The effect of MSC blocker GsMTx-4 on photoresponses from Xenopus rods.

Fig 5

(A) IS of a rod trapped in a recording pipette and a glass pipette connected to a picospritzer, containing GsMTx-4. Upon the activation of the picospritzer, the rod OS was tilted and returned to its initial position (scale bar, 20 μm). (B) The photocurrent elicited by flashes of about 2,500 R*/rod before, during, and after an exposure to GsMTx-4 lasting 120 s. (C) Exposure to GsMTx-4 (red trace) shortens the duration of the bright-flash photoresponse by more than 1 s compared with those obtained immediately before (black) and immediately after (blue) exposure to GsMTx-4; mean duration (measured as the difference in time between 50% of the falling phase and 50% of the rising phase of the response) 4.7 ± 1.8 s in control and 3.4 ± 1.3 s in GsMTx-4 (p < 0.001). (D and E) As in B and C, but the picospritzer injected Ringer solution. Mean duration 6.2 ± 1.7 s in control and 5.9 ± 1.9 s in Ringer (ns). (F) Comparison of photoresponses in control conditions (black traces) and in the presence of GsMTx-4 (red traces) for 1 cell exposed to flash of approximately 5, 10, 25, 50, 100, 250, 500, 1,000, and 2,500 R*/rod. (G) As in F, but in this case each trace was averaged over photoresponses obtained from 6–7 different rods. The amplitude of the maximal photoresponse was normalized to unity for recordings both in Ringer (black traces) and in the presence of GsMTx-4 (red traces). (H) The effect of GsMTx-4 on dim flash photoresponses for one cell; the flash intensities were 5 and 10 R*/rod (n = 6–7). (I) Relation between the GsMTx-4-induced shortening (ΔT) of photoresponse duration and the Tsat of the response. For 250, 500, 1,000, and 2,500 R*/rod, the shortened time courses were of 0.3 s, p < 0.05; 0.5 s, p < 0.01; 0.7 s, p < 0.05; and 1.3 s, p < 0.001, respectively. In all experiments, the concentration of GsMTx-4 in the picospritzer pipette was 5 μM, we estimate that at the rod OS was in the micromolar range; n = 6–7 (S4 Data). GsMTx-4, M-theraphotoxin-Gr1a; IS, inner segment; MSC, mechanosensitive channel; OS, outer segment; Tsat, saturation time.