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. Author manuscript; available in PMC: 2015 Jul 1.
Published in final edited form as: Pflugers Arch. 2014 Jul;466(7):1301–1316. doi: 10.1007/s00424-013-1362-5

Fig. 2.

Fig. 2

Pressure ejection of DHPG elicits below-threshold-depolarization (BTD) and above-threshold-plateau depolarization (ATPD) as well as the corresponding changes in membrane excitability of LS neurons in whole-cell recordings. A, Representative traces showing changes in membrane potential and firing activity elicited by ejecting aCSF (a) or 30 µM DHPG (b–d) onto WT (TRPC4+/+) LS neurons held at −45 mV (CC-45). Arrows (a–c) indicate the time of ejection (5–20 psi, 30 ms). d, the boxed area of c in an expanded time scale with the ejection period indicated by the black bar. Note aCSF ejection did not change the resting membrane potential or interfere with LS firing (a), but DHPG ejection onto LS neurons elicited either BTD and the accompanied increase in firing rate (b) or ATPD, comprising an initial burst and then an extended plateau depolarization, and the accompanied burst firing followed by a momentary pause of firing during the plateau depolarization (c and d A T P D). Scale bars: 0.5 s, 10 mV (a–c); 100 ms, 10 mV (d). B, Example trace of spontaneous burst firing of an LS neuron during whole cell current clamp recording (without current injection). Scale bars: 100 ms, 10 mV. C, Similar to Ab, but showing that DHPG ejection onto the TRPC4−/− LS neuron elicited an initial decrease, followed by an increase in firing rate. D, Left, proportions of silent and firing TRPC4+/+ LS neurons held at −45 mV. Right, scattered distributions and mean±SEM values of DHPG-evoked membrane depolarization of silent (n =9) and firing LS neurons (n =58). E, Distribution of peak depolarization amplitude evoked by DHPG ejection at CC-45 for TRPC4+/+ neurons. Note the bimodal segregation of BTD and ATPD. F, G, Average (mean±SEM) peak depolarization amplitudes (F) and time-to-peak values (G) of BTD (n =18) and ATPD (n =49) for TRPC4+/+ and all TRPC4−/− LS neurons (n=9). **P <0.01, compared to BTD. H, Average firing frequency 1 s before and 1 and 2 s after DHPG ejection onto BTD TRPC4+/+ and all TRPC4−/− LS neurons. *P<0.05, **P <0.01, compared to BTD at −1 s; ##,++P <0.01, compared to BTD at 1 and 2 s, respectively