Omega AGA toxin IVA blocks high-voltage-activated calcium channel currents in cultured pars intercerebralis neurosecretory cells of adult locusta migratoria.

Using the whole cell patch-clamp technique, calcium (Ca) channel currents from cultured medial neurosecretory cells (MNSCs) of Locusta migratoria (Rössler and Bickmeyer, 1993) were investigated. The calcium channel blocker omega AGA toxin IVA (AGA IVA) blocks a fraction of these calcium channel currents in approximately 30% of MNSCs, without a shift in the I-V relationship. The block can be at least partially reversed by strong depolarizing voltage pulses as described for vertebrate neurones from Mintz et al. (1992). The existence of probably more than three calcium channel types in insects is discussed.