title: An antidiuretic peptide (Tenmo-ADFb) with kinin-like diuretic activity on Malpighian tubules of the house cricket, Acheta domesticus (L.).
abstract: Acheta domesticus is reported to have an antidiuretic hormone that reduces Malpighian tubule secretion. Identified peptides known to work in this way (Tenmo-ADFa and ADFb, and Manse-CAP(2b)) were tested as candidates for the unidentified hormone, along with their second messenger, cyclic GMP. Only Tenmo-ADFb was active, but was diuretic, as was 8-bromo cyclic GMP. The activity of Tenmo-ADFb is comparable to that of the cricket kinin neuropeptide, Achdo-KII, but it is much less potent. Its activity was unaffected by deleting either the six N-terminal residues or the C-terminal phenylalanine. At high concentrations, tubule secretion is doubled by Tenmo-ADFb and Achdo-KII, but their actions are non-additive, suggesting they have a similar mode of action. Both stimulate a non-selective KCl and NaCl diuresis, which is consistent with the opening of a transepithelial Cl(-) conductance. In support of this, the diuretic response to Tenmo-ADFb and Achdo-KII is prevented by a ten-fold reduction in bathing fluid chloride concentration, and both peptides cause the lumen-positive transepithelial voltage to collapse. The Cl(-) conductance pathway appears likely to be transcellular, because the Cl(-) channel blocker DPC reduces both basal and peptide-stimulated rates of secretion. The effects of 8-bromo cyclic GMP on transepithelial voltage and composition of the secreted fluid are markedly different from those of Tenmo-ADFb. This is the first report of the antidiuretic factor Tenmo-ADFb stimulating tubule secretion. Although the actions of Tenmo-ADFb are indistinguishable from those of Achdo-KII, it is unlikely to act at a kinin receptor, because the core sequence (residues 7-12) lacks the Phe and Trp residues that are critical for kinin activity.
authors.affiliation: School of Biological and Chemical Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK. g.coast@bbk.ac.uk
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Coast
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Nachman
authors.forename: David A
authors.initials: DA
authors.lastname: Schooley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D050034:Antidiuretic Agents / Q000494:pharmacology*; D001826:Body Fluids / Q000187:drug effects / Q000378:metabolism; D002412:Cations; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology*; D004357:Drug Synergism; D004594:Electrophysiology; D004848:Epithelium / Q000187:drug effects; D005260:Female; D041981:Gastrointestinal Tract / Q000187:drug effects; D006135:Gryllidae / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007705:Kinins / Q000494:pharmacology*; D008317:Malpighian Tubules / Q000187:drug effects*; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D050034:Antidiuretic Agents; D002412:Cations; D018118:Chloride Channels; D004232:Diuretics; D007705:Kinins; D010455:Peptides; C016276:8-bromocyclic GMP; D006152:Cyclic GMP