1. Neurons were Stimulated Using a Piezo-Electric Controlled Heat-Polished Glass Pipette
Perforated Patch
Configuration
Neurons 1 day
in culture
Tests:
Series 2m increments
Repeated stimulus

2. LJ Drew, TM Jessell, JN Wood &
Characterisation of Mechanically Activated Currents in Dorsal Root Ganglia Neurons
LJ Drew, TM Jessell, JN Wood &
P Cesare

3. Capsaicin Sensitive and Insensitive Neurons are Differentially Responsive to Mechanical Stimulation
Stimuli 12 mm
Inward Currents
3000
2000
Current Amplitude (pA)
-3000
1000 pA
-600 2 4 6 8 10 12
Displacement (mm)
Caps - Rapidly adapting
-500
Caps - Slowly adapting
300
Caps + Rapidly adapting
Time (msec)

4. Blockade of MA Currents by Ruthenium Red and Gadolinium in Different Subpopulations
100
100
% Inhibition 50 50
0.1 1 10
100
0.1 1 10
100
Log10 [Gd3+] (mM)
Log10 [Ruthenium Red] (mM)
Caps + Rapidly adapting
Caps - Rapidly adapting
Caps - Slowly adapting

5. MA Currents in Subsets of DRG Neurons are Differentially Modulated by Ca2+
Caps -
0mM Ca2+
+100 pA
-500
+50
5mM Ca2+
-1000
% Control (2mM Ca2+)
Caps +
-50 pA
-400
Caps -
5mM Ca2+
-100
Caps +
Control
-800
0mM Ca2+

6. MA Currents Are Acutely Inhibited by Cytochalasin B (10M) in Capsaicin Insensitive Neurons
100 80 60
% Control 40 20
Caps -
Caps +

7. Are MA Currents ASIC Mediated?
ASIC2 and ASIC3 KO Mice show moderate changes in mechanosensitivity.
Magnitude of MA currents does not correlate with rapidly adapting low pH evoked currents.
MA currents are not modulated by low pH.
MA currents are not sensitive to Amiloride.
MA currents are blocked by 300M Zn2+.

8. Conclusions
Important aspects of the mechanosensitive phenotype of DRG neurons are maintained in vitro.
Pharmacology: MA Currents are mediated by closely related ion channels in low- and high-threshold neurons.
Ca2+ modulation reveals diversity in MA current modulation.
Sensitivity of ion channels may be determined by cytoskeletal tethering.