Facilitation of membrane electrical excitability in Drosophila

Prior electrical activity in the indirect flight muscles of Drosophila facilitates membrane excitability. The mechanism of facilitation involves the inactivation of an early, fast, transient outward current by prior membrane depolarizaton. In the facilitated state the calcium-dependent spike-like response has a decreased current and voltage threshold. The facilitated state persists for 1.5 sec after a membrane active response. A single nerve-driven spike is sufficient to facilitate membrane excitability.