Figure 5. The plasma membrane Ca²⁺-ATPase (PMCA), but not the Na⁺–Ca²⁺ exchanger, plays a significant role in Ca²⁺ homeostasis in corneal nerve terminals (CNTs).

A, Ca²⁺ transients evoked in CNTs by electrical field stimulation (50 stimuli at 10 Hz) before (blue) and after (red) 10 min incubation with 10 μm KB-R7943 (traces are average data from n = 6 CNTs). The Ca²⁺ transients had similar amplitudes (P = 969, n = 6) and 95%–10% decay times (P = 0.943). B, Ca²⁺ transients evoked in a CNT by electric field stimulation (50 stimuli at 10 Hz) before (blue) and after (red) 25 min exposure to alkaline extracellular pH (pH_o 9.0) to block the PMCA. The Ca²⁺ transient amplitudes were similar (P = 0.688, n = 6); however, decay of the transients was much slower at pH 9.0 than at pH 7.3 (95%–10% decay times were 2-fold longer; P = 0.006).