Characterization of voltage-gated calcium channels in Xenopus oocytes after injection of RNA from electrically excitable tissues

Abstract

The entry of Ca²⁺ through voltage-gated channels has two major functions. First, Ca²⁺ fluxes elevate the intracellular concentration of this important second messenger. Second, Ca²⁺ currents directly influence membrane potential, thereby contributing to impulse patterns. Ca²⁺ channels serve these functions in a variety of nerve, muscle, and endocrine cells (Reuter, 1983; Tsien, 1983). As might be expected from their wide distribution and their role in regulating a number of cellular functions, voltage-gated Ca²⁺ channels form a heterogeneous family. Diverse types of Ca²⁺ channels can be distinguished with regard to gating kinetics, pharmacology, and permeability (Fox and Krasne, 1981; Armstrong and Matteson, 1985; Nowyeky et al., 1985). For the purpose of characterizing the various forms of voltage-gated Ca²⁺ channels, it would be desirable to study them in a similar membrane environment.