Figure 6. Astrocytic Ca²⁺ clamp prevents suppression of field EPSPs by GABA.

(a) Time course (left) and a summary plot (right) of the effects of GABA on normalized field EPSPs recorded through CA1 passive astrocytes (aEPSPs; n=6 cells from 5 animals). Inset: An example of a patched astrocyte loaded with Alexa 594 and sample traces of aEPSPs (conditions indicated above traces). Image scale bar, 20 μm, aEPSP scale bars: vertical 0.2 mV, horizontal 30 ms. (b) Single cell examples and summary plots (n=5 cells from 4 animals) of GABA effect on aEPSPs recorded though an astrocyte filled with an internal solution buffered to a nominal Ca²⁺ concentration of 50–80 nM (Ca²⁺ clamp). Layout as in a; vertical aEPSP scale bar, 0.3 mV, horizontal 30 ms; image scale bar, 20 μm; error bars represent s.e.m.'s; *P<0.05, **P<0.01, n.s.—non-significant (paired t-test).