Inhibition of high voltage-activated Ca²⁺ currents from cultured sensory neurones by a novel insect peptide

Abstract

PMP-D2, a novel 35 amino acid peptide isolated from the brain of the locust Locusta migratoria, is localised specifically in neurosecretory cells and nerve tracts of the Pars intercerebralis. When PMP-D2 is applied onto rat sensory neurones it blocks high voltage-activated inward Ca²⁺ currents at concentrations ranging from 0.1 μM to 10 μM. The inhibitory effect of PMP-D2 is more marked on the sustained inward Ca²⁺ current measured at the end of 100 ms voltage step commands than on the maximum inward Ca²⁺ current. These results suggests that PMP-D2 may differentially inhibit the two components of the high voltage-activated inward Ca²⁺ currents of rat sensory neurones.