Voltage-Induced Intracellular Calcium Signals Depend on G-protein Activation

<div><p>Acutely isolated neurons are loaded with GTPγS (100 μM), and a voltage step from −90 mV to 0 mV is repeated 30 times in calcium-containing saline to minimize availability of native G-protein.</p> <p>(A) In calcium-containing saline depolarization causes calcium inward current accompanied by an intracellular calcium signal.</p> <p>(B) Exposing the GTPγS-loaded cell for 3 min to zero-calcium saline causes a complete loss of membrane currents and the calcium signal.</p> <p>(C) Switching back to calcium-containing saline for 3 min restores the original current and the calcium signal.</p>