Figure 6. The oestrogen effect on the L-type Ca²⁺ current and C_m changes.

A, the difference in nifedipine-sensitive Ba²⁺ current density between adult male, adult female and newborn (NB) melanotrophs. HVA peak Ba²⁺ current amplitudes were statistically different (P < 0.002; one-way ANOVA). Numbers on bars represent the number of cells tested. B, typical nifedipine-sensitive Ba²⁺ current recordings from the adult male (black trace), adult female (red trace) and newborn (NB) melanotroph (grey trace). Note the comparable LVA component and the different HVA current between adult male, adult female and newborn (NB) melanotrophs. C, the representative Ca²⁺ current recording from male melanotrophs incubated 24 h in 1 nm 17β-oestradiol before (arrow) and after nifedipine treatment (arrow). A major part of the Ca²⁺ current amplitude was nifedipine sensitive (red trace). D, the representative normalized cumulative membrane capacitance responses to the train of depolarizing pulses from male melanotrophs incubated 24 h in 17β-oestradiol before and after the nifedipine treatment (black traces). Secretory responses of control male melanotrophs only incubated in phenol red-free medium before and after the nifedipine treatment (red traces). Note that cumulative C_m was normalized to the Ca²⁺ influx. E, the difference in the nifedipine-sensitive Ca²⁺ current density between male melanotrophs in control conditions, 17β-oestradiol-treated male pituitary slices and pregnant female (day 19). HVA peak Ca²⁺ current amplitudes in males were statistically different (P < 0.002; one-way ANOVA). Numbers on bars show the number of cells tested. F, the comparison of C_m response in pregnant female, 17β-oestradiol treated male pituitary slices and male melanotrophs in control conditions. C_m responses were statistically different (P < 0.002; one-way ANOVA). Numbers on bars show the number of cells tested.