11316500

pubmed:Citation

Pt 10

The Drosophila melanogaster homologue of an insect calcitonin-like diuretic hormone was identified in a BLAST search of the Drosophila genome database. The predicted 31-residue amidated peptide (D. melanogaster DH31; Drome-DH31) was synthesised and tested for activity on fruit fly Malpighian tubules. It increases tubule secretion by approximately 35 % of the response obtained with a myokinin from the housefly Musca domestica (muscakinin; Musdo-K) and has an EC50 of 4.3 nmol x l(-1). The diuretic activities of Drome-DH31 and Musdo-K were additive when tested at threshold and supra-maximal concentrations, which suggests that they target different transport processes. In support of this, Drome-DH31 increased the rate of secretion by tubules held in bathing fluid with a reduced Cl- concentration, whereas Musdo-K did so only in the presence of Drome-DH31. Stimulation with Drome-DH31 increased the lumen-positive transepithelial potential in the main secretory segment of the tubule. This was attributed to activation of an apical electrogenic proton-translocating V-ATPase in principal cells, since it was associated with hyperpolarisation of the apical membrane potential and acidification of secreted urine by 0.25 pH units. Exogenous 8-bromo-cyclic AMP and cyclic GMP increased tubule secretion to the same extent as Drome-DH31 and, when tested together with the diuretic peptide, their activities were not additive. Stimulation with Drome-DH31 resulted in a dose-dependent increase in cyclic AMP production by tubules incubated in saline containing 0.5 mmol x l(-1) 3-isobutyl-1-methylxanthine, whereas cyclic GMP production was unchanged. Taken together, the data are consistent with Drome-DH31 activating an apical membrane V-ATPase via cyclic AMP. Since the K+ concentration of the secreted urine was unchanged, it is likely that Drome-DH31 has an equal effect on K+ and Na+ entry across the basolateral membrane.

eng

IM

MEDLINE

0022-0949

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NLM

1795-804

pubmed-meshheading:11316500-1-Methyl-3-isobutylxanthine, pubmed-meshheading:11316500-Amino Acid Sequence, pubmed-meshheading:11316500-Animals, pubmed-meshheading:11316500-Bucladesine, pubmed-meshheading:11316500-Cyclic AMP, pubmed-meshheading:11316500-Cyclic GMP, pubmed-meshheading:11316500-Dose-Response Relationship, Drug, pubmed-meshheading:11316500-Drosophila Proteins, pubmed-meshheading:11316500-Drosophila melanogaster, pubmed-meshheading:11316500-Female, pubmed-meshheading:11316500-Hydrogen-Ion Concentration, pubmed-meshheading:11316500-Insect Hormones, pubmed-meshheading:11316500-Insect Proteins, pubmed-meshheading:11316500-Male, pubmed-meshheading:11316500-Malpighian Tubules, pubmed-meshheading:11316500-Membrane Potentials, pubmed-meshheading:11316500-Molecular Sequence Data, pubmed-meshheading:11316500-Muscidae, pubmed-meshheading:11316500-Neuropeptides, pubmed-meshheading:11316500-Phosphodiesterase Inhibitors, pubmed-meshheading:11316500-Proton-Translocating ATPases, pubmed-meshheading:11316500-Sequence Alignment, pubmed-meshheading:11316500-Urine, pubmed-meshheading:11316500-Vacuolar Proton-Translocating ATPases

The Drosophila melanogaster homologue of an insect calcitonin-like diuretic peptide stimulates V-ATPase activity in fruit fly Malpighian tubules.

Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't