Fig. 4.

End-plate sensitivity to iontophoretically applied acetylcholine (ACh) increased for muscle end plates of mice at 2 wk after the onset of STZ-induced hyperglycemia. A: representative recordings of iontophoretically evoked ACh potentials recorded at end plates of the Triangularis sterni muscle of control mice and mice with 2 wk of STZ-induced hyperglycemia. For each recording, the top trace is the end-plate potential response and the bottom trace the current injected through the iontophoretic pipette containing 3 M ACh. These records illustrate the increased amplitude and prolonged decay time of the ACh-induced potential. B: average ACh sensitivity increased at 2 wk after onset of STZ-induced hyperglycemia. ACh sensitivity was calculated as the ratio of membrane potential response to nCoul of charge passed through the ACh pipette. Bars represent ACh sensitivity (mean + SE) obtained from 14 to 19 recordings from different end plates in 3 muscles from the control and the hyperglycemic groups. **P < 0.05.