Calcium Channel Currents In Neurones From Locust (Schistocerca Gregaria) Thoracic Ganglia Available to Purchase

Using the patch-clamp technique, Ca²⁺ channel currents were recorded from neurones freshly isolated from the thoracic ganglia of the desert locust Schistocerca gregaria.

In solutions containing 10mmol l⁻¹Ba²⁺ we observed high-voltage-activated whole-cell inward currents with sustained and transient components, both of which had similar steady-state inactivation properties.

Substitution of Ca²⁺ for Ba²⁺ was found to reduce whole-cell currents, whereas removal of monovalent cations had no effect.

Cd²⁺ (1mmol l⁻¹) completely blocked the whole-cell current, but at 10 μmol l⁻¹ preferentially inhibited the sustained component without affecting the transient component.

Verapamil (1 μmol l⁻1) inhibited both current components but appeared to be more

selective for the sustained component, whereas nitrendipine (1 μmol l⁻¹) had no effect on either component.

A single-channel recording suggested that the transient component was carried by a low-conductance channel.

Certain compounds with insecticidal action (ryanodine, S-bioallethrin, deltamethrin and avermectin) did not affect calcium channel currents in these cells.

These data suggest that there are two types of Ca²⁺ channels present in locust neurones. These channel types have properties differing from the T-, L- and N-type channels found in vertebrates and, furthermore, were not targets for the insecticides we tested.