Postnatal development of voltage-dependent calcium channels in the mouse brain disclosed by the Xenopus oocyte assay

We assessed the ontogeny of murine voltage-dependent calcium channels by extracting mRNA from brains of mice at different postnatal ages and injecting the mRNA into oocytes of the frog, Xenopus laevis. Voltage-dependent Ca2(+)-activated Cl- channels were measured to assess the presence of Ca2(+) channels. When compared with water-injected oocytes (controls), an increase in Ca2(+) channels was not detected until postnatal day 7. The number of Ca2+ channels peaked between 9 and 18 days and began to decline by 35 days. Bath application of barium, serotonin and the Ca2+ channel antagonist, verapamil, to mRNA-injected oocytes confirmed the presence of Ca2+ channels.