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. 2006 May 17;26(20):5370–5382. doi: 10.1523/JNEUROSCI.5255-05.2006

Figure 4.

Figure 4.

Blockade of heterosynaptic depression by BAPTA dialysis in glial cells. A, Schematic representation of area CA1 in a rat hippocampal slice, showing positions of two stimulating electrodes [Test; Tet. (tetanus)], a single fEPSP recording electrode placed in the stratum radiatum, and a single whole-cell patch-clamp electrode recording from a glial cell. The experimental protocol is illustrated at the bottom. B, Data from a representative slice (top panel) and for all slices (bottom panel; n = 7 slices) showing changes in fEPSP amplitude as percentage of baseline before, during, and after tetanic stimulation of an independent pathway (arrow) (3 trains at 100 Hz for 1 s; 30 s intervals) in paired control experiments (gray) and after whole-cell dialysis of 0.1 mm BAPTA in the glial syncytium (black). Dialysis of 0.1 mm BAPTA in glial cells did not affect tetanization-induced heterosynaptic depression (Student’s paired t test; p > 0.3). Top panel insets show examples of fEPSPs before (1) and during (2) heterosynaptic depression in control and after dialysis of 0.1 mm BAPTA (3). Calibration: 1 mV, 20 ms. C, Data from a single slice (top panel) and for all slices (bottom panel; n = 7 slices) showing changes in fEPSP amplitude as percentage of baseline before, during, and after tetanic stimulation of an independent pathway (arrow) (3 trains at 100 Hz for 1 s; 30 s intervals) in paired control experiments (gray) and after whole-cell dialysis of 40 mm BAPTA in the glial syncytium (black). Note that heterosynaptic depression was obliterated in the presence of a high concentration of the Ca2+ chelator. Dialysis of 40 mm BAPTA in glial cells did not affect the initial phase but reduced significantly the sustained phase of the tetanization-induced heterosynaptic depression (Student’s paired t test; p < 0.01). Top panel insets show examples of fEPSPs before (1) and during (2) heterosynaptic depression in control, and in the presence of a high concentration of intraglial BAPTA (3). D, Bar graphs showing the amplitude of the initial and the sustained phase of heterosynaptic depression induced by tetanic stimulation in control (gray) and after dialysis of 40 mm BAPTA (black). Error bars indicate SEM. Ctrl, Control. *p < 0.05.