Table 1Effects of AC1 Knockout on Some Basal Properties of Cerebellar Neurons in Culture
Purkinje
Granule
Measure
AC1 KO
129 wt
AC1 KO
129 wt
Vm
−72 ± 5 mV (5)
−69 ± 6 (5)
−75 ± 4 (6)
−77 ± 5 (7)
Rinput
167 ± 24 MΩ (5)
175 ± 22 (5)
1195 ± 211 (6)
1080 ± 185 (7)
Resting Cai (2 mM Cao)
97 ± 12 nM (7)
105 ± 15 (6)
84 ± 18 (7)
90 ± 15 (8)
Depol-evoked Cai
452 ± 51 nM (7)
469 ± 58 (6)
586 ± 70 (7)
514 ± 56 (8)
Resting Cai (0 Cao)
26 ± 8 nM (10)
25 ± 7 (11)
30 ± 7 (12)
34 ± 7 (10)
Quis-evoked Cai
209 ± 26 nM (10)
233 ± 26 (11)
ND
ND
mEPSC frequency
7.1 ± 2.9 s−1 (6)
9.9 ± 2.7 (6)
ND
ND
mEPSC amplitude
23 ± 6 pA (6)
25 ± 6 (6)
ND
ND
Paired-pulse facilitation
157 ± 10% (8)
160 ± 9% (8)
ND
ND
Values are mean ± SEM. n is indicated in parentheses. All measures were made in tetrodotoxin-containing (0.5 μM) saline. Vm was measured in a separate set of cells using a K-based internal saline. Rinput measurements were made using a Cs-based saline in the same Purkinje neurons illustrated in Figure 4. Vm was determined by briefly switching the recording circuit to current clamp mode at t = −7.5 min. Rinput was determined by measuring the sustained current deflection during a voltage step from −80 to −90 mV at t = −5 min. Fura-2 microfluorimetric measurements of depolarization-evoked and metabotropic agonist–evoked Ca were conducted in cells separate from those of the LTP/LTD experiments. Values are peak proximal dendritic Ca concentration for Purkinje neurons and peak somatic Ca for granule neurons. Depolarization-evoked Cai was measured in cells that were incubated in normal (2 mM Ca-containing) external saline and stimulated with a 3 s depolarizing pulse from −80 to 0 mV. Quisqualate-evoked Cai, a measure of group I mGluR function, was measured in cells that were incubated in 0 Ca/0.2 EGTA external saline and stimulated with a pressure pulse of 100 μM quisqualate (dissolved in 0 Ca/0.2 EGTA saline, 6 psi, 2 s). This pressure pulse delivered agonist to the entire cell. Resting values were measured immediately before stimulation. Depolarization-evoked values were measured as the peak during a 30 s measuring period following the onset of depolarization, and quisqualate-evoked values were measured as the peak during a 120 s measuring period following the onset of the pressure pulse. mEPSC frequency and amplitude measurements were made using the same cells shown in Figure 6. Paired-pulse facilitation was assessed using granule cell–Purkinje cell pairs stimulated at an interval of 50 ms in tetrodotoxin-free saline. Mean EPSC amplitudes were derived by averaging 30 consecutive paired stimuli applied at 0.05 Hz and were then normalized to derive the % facilitation measure.
