Purinergic reception by culicine mosquitoes

Publisher Website
Google Scholar
Abstract
Adult femaleCulex pipiens andCuliseta inornata have purinergic receptors that respond to extracellular ADP and related compounds. Stimulation of these receptors caused ingestion of artificial diets. Addition of bicarbonate to the saline solvent enhanced the phagostimulatory effect. Saline-bicarbonate was as effective a solvent as blood plasma forCx. pipiens, and was used in the dose-effect determinations. Ranking of the potencies was: ADP>AMP-PNP>ATP= AMP>AMP-PCP≫2′dAMP>2′dADP>2′dATP. At 1 mM concentration, ITP, GTP, CTP, UTP, c-AMP, 2′AMP, 3′AMP, DPG, or GSH+glucose caused fewer than 50% of the insects to gorge, as did 2′3′dd-ATP, A tetra P, and AMP-CPP at 100μM. The potency ranking forCu. inornata was: ADP>AMP-PNP>ATP>AMP-PCP≫AMP≫ AMP-S. The concentrations required to produce the ED50 response (inducing 50% of the test insects to gorge) were much higher than those required forCx. pipiens; however, saline, not salinebicarbonate, was used as the solvent. With the exception of the very low potency of AMP forCu. inornata, the ADP potency index values for the other chemicals tested on both species are similar. Two hypotheses are advanced to explain the results: either these mosquitoes have a purinoceptor system that differs from the p1 or P2 type of receptors found in vertebrates and some crustaceans, or they have receptors similar to both the p1 and P2 types and are responding to a combination of inputs.