Functional properties of NMDARs in neurons of the basal ganglia
| Cell type | Deactivation τ1(msec) | τ2 (msec) | Amplitude fast (%) | Mg2+ block (g−60mV/g+40mV) | Peak current NP, −60 mV (pA) |
|---|---|---|---|---|---|
| Striatum | |||||
| Striatal principal neurons | 147 ± 19 | 1088 ± 255 (5) | 73 ± 4 | 0.21 ± 0.01 (7) | 65 ± 12 (7) |
| Striatal cholinergic interneurons | 130 ± 18 | 687 ± 110 (6) | 61 ± 3 | 0.20 ± 0.02 (8) | 59 ± 13 (6) |
| Substantia nigra | |||||
| Nigral GABAergic neurons | 142 ± 5 | 797 ± 158 (5) | 70 ± 2 | 0.22 ± 0.01 (6) | 137 ± 44 (5) |
| Nigral dopaminergic neurons | 150 ± 12 | 1049 ± 107 (7) | 66 ± 4 | 0.21 ± 0.03 (8) | 154 ± 31 (7) |
| Globus pallidus and subthalamic nucleus | |||||
| Globus pallidus neurons | 67 ± 10 | 382 ± 80 (6) | 59 ± 6 | 0.21 ± 0.02 (6) | 60 ± 14 (6) |
| Subthalamic nucleus neurons | 137 ± 16 | 833 ± 225 (6) | 73 ± 6 | 0.18 ± 0.03 (6) | 169 ± 61 (7) |
The deactivation time constants of NMDARs were determined by using 10 msec pulses of 100 μm glutamate in Mg2+-free Na+-rich external solution and fitting the decay phase with the sum of two exponentials. The contribution of the fast component to the total decay amplitude also was assessed from the biexponential fit. The rectification index of the NMDAR-mediated current, g−60mV/g+40mV, was determined from the I–V relation in Na+-rich external solution containing 100 μmMg2+. The peak current amplitude at −60 mV was determined in Mg2+-free Na+-rich external solution. All data were obtained from nucleated patches (NP).