Electrophysiology of Mosquito Anal Papillae

The anal papillae of mosquito larvae are classic transporting epithelia that can absorb inorganic ions from extremely dilute external media. Since the original investigations of Wigglesworth (1933a,b,c) and Koch (1938) studies have been made of the ultrastructure of the papillae (Copeland, 1964; Sohal & Copeland, 1965; Meredith & Phillips, 1973a,6), of radio-cation fluxes (Treherne, 1954; Stobbart, 1959, 1960, 1965, 1967, 1971), of their water permeability (Nicolson & Leader, 1974) and their role in osmoregulation (Edwards, 1979). Quantitative understanding of epithelial salt transporting mechanisms, however, requires knowledge of the appropriate electrochemical gradients. Only one attempt has so far been made to provide this information for mosquito larvae (Stobbart, 1974). These measurements were made by recording the potentials between the larval haemolymph and a drop of fluid surrounding the papillae. However, the potentials measured in this way were found to be very unstable and of variable polarity. This communication describes an attempt to measure the electrical properties of the papilla epithelium using isolated anal papillae oiAedes aegypti.