TASTE RECEPTION MECHANISMS IN THE BLOWFLY - EVIDENCE OF AMILORIDE-SENSITIVE AND INSENSITIVE RECEPTOR-SITES

The role of amiloride in the labellar responses to various taste stimu li in the blowfly Protophormia terraenovae was studied with the aim of ascertaining whether amiloride-sensitive cation conductances are pres ent in the chemosensory systems of insects. Results indicate that: 1) amiloride has no effect on the ''salt'' cell response to any stimulus; 2) amiloride decreases the ''sugar'' cell response to fructose, but d oes not affect that to sucrose; 3) the effects of amiloride on the res ponses of the ''water'' cell and the ''fifth'' cell are less clearly d efinable, due to the probable superimposition of osmotic mechanisms in the former and the poorly known response modalities of the latter. In conclusion, amiloride-sensitive receptor sites seem to exist also in insects. However, unlike most vertebrates investigated, they are princ ipally located on the sugar receptor cell, not on the salt cell. (C) 1 997 Elsevier Science Inc.