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The functional properties of low‐voltage‐activated (LVA) Ca²⁺ channels were studied in pyramidal neurones from different rat visual cortical layers in order to investigate changes in their properties during early postnatal development. Ca²⁺ currents were recorded in brain slices using the whole‐cell patch‐clamp technique in rats from three age groups: 2, 3 and 12 days old (postnatal day (P) 2, P3 and P12).

It was demonstrated that LVA Ca²⁺ currents are present in neurones from superficial (I‐II) and deep (V‐VI) visual cortex layers of P2 and P3 rats. No LVA Ca²⁺ currents were observed in neurones from the middle (III‐IV) layers of these rats. The LVA Ca²⁺ currents observed in P2 and P3 neurones from both superficial and deep layers could be completely blocked by nifedipine (100 μM) and were insensitive to Ni²⁺ (25 μM).

The density of LVA Ca²⁺ currents decreased rapidly during the early stages of …