Journal: The Journal of physiology
Article Title: Diurnal properties of voltage-gated Ca2+ currents in suprachiasmatic nucleus and roles in action potential firing
Figure Lengend Snippet: Relative contribution of voltage-gated calcium currents in the SCN. Macroscopic voltage-activated calcium currents recorded in whole-cell voltage-clamp mode during the day or night. From a holding potential of −90 mV, currents were elicited from 150-ms voltage steps in 10-mV increments. A , Representative total Ca 2+ currents before (control) and after addition of Cd 2+ . B , Current-voltage relationships for the total Ca 2+ current and Cd 2+ -sensitive components, versus L-, N-, P/Q-, R-, and T-type subtypes of the Ca 2+ current (Cd 2+ -sensitive, 200 μM; Nimodipine-sensitive, 10 μM; ConoMVIIC-sensitive, 3 μM; ConoGVIA-sensitive, 3 μM; AgaIVA-sensitive, 200 nM; Ni 2+ -sensitive, 30 μM; and TTAP2-sensitive, 1 μM). One Ca 2+ current subtype was isolated per cell by application of an inhibitor and subtraction from the baseline current (total Ca 2+ ). C , The relative contribution of each inhibitor-sensitive current to the total Ca 2+ current in day and night, calculated from the peak current. Due to the variation in current magnitudes from cell to cell (and overlapping specificities of the drugs), the sum of the individual inhibitors exceeds 100%. N’s are the number of neurons recorded (day, night): Cd 2+ (12, 10), Nimodipine, (21, 20), ConoMVIIC (7, 7), ConoGVIA (11, 8), AgaIVA (17, 18), Ni 2+ (9, 8), TTAP2 (4, 4). Data were obtained from 3–8 slices per condition as follows (# slices day, # slices night): Cd 2+ (3, 3), Nimodipine, (8, 8), ConoMVIIC (2, 2), ConoGVIA (4, 4), AgaIVA (7, 6), Ni 2+ (3, 3), TTAP2 (2, 4). Total Ca 2+ currents were obtained at baseline from all recordings (n=96 neurons in 35 slices for day and 82 neurons in 33 slices for night).
Article Snippet: Drugs were used at final concentrations of 1 μM tetrodotoxin (TTX; Alomone Labs, Jerusalem, Israel; T-550), 10 μM Nimodipine (Alomone Labs, Jerusalem, Israel; N150), 10 μM dantrolene (Dan; Sigma, Darmstadt, Germany; D9175), 1 μM cyclopiazonic acid (CPA; Alomone Labs, Jerusalem, Israel; C-750), 3 μM ω-conotoxin GVIA (ConoGVIA; Alomone Labs, Jerusalem, Israel; C-300), 3 μM ω-conotoxin MVIIC (ConoMVIIC; Alomone Labs, Jerusalem, Israel; C-150), 200 nM ω-agatoxin IVA (AgaIVA;Alomone Labs, Jerusalem, Israel; STA-500), 1 μM TTA-P2, (TTAP2;Alomone Labs, Jerusalem, Israel; T-155), 200 μM CdCl2 (Cd2+ ; Sigma; 529575), 30 μM NiCl2 (Ni2+ ; Sigma; 22387), and 5 μM Bay K8644 (Bay K; Sigma, Darmstadt, Germany; B133).