title: Model organisms: new insights into ion channel and transporter function. L-type calcium channels regulate epithelial fluid transport in Drosophila melanogaster.
abstract: The neuropeptide CAP2b stimulates fluid transport obligatorily via calcium entry, nitric oxide, and cGMP in Drosophila melanogaster Malpighian (renal) tubules. We have shown by RT-PCR that the Drosophila L-type calcium channel alpha1-subunit genes Dmca1D and Dmca1A (nbA) are both expressed in tubules. CAP2b-stimulated fluid transport and cytosolic calcium concentration ([Ca2+]i) increases are inhibited by the L-type calcium channel blockers verapamil and nifedipine. cGMP-stimulated fluid transport is verapamil and nifedipine sensitive. Furthermore, cGMP induces a slow [Ca2+]i increase in tubule principal cells via verapamil- and nifedipine-sensitive calcium entry; RT-PCR shows that tubules express Drosophila cyclic nucleotide-gated channel (cng). Additionally, thapsigargin-induced [Ca2+]i increase is verapamil sensitive. Phenylalkylamines bind with differing affinities to the basolateral and apical surfaces of principal cells in the main segment; however, dihydropyridine binds apically in the tubule initial segment. Immunocytochemical evidence suggests localization of alpha1-subunits to both basolateral and apical surfaces of principal cells in the tubule main segment. We suggest roles for L-type calcium channels and cGMP-mediated calcium influx in both calcium signaling and fluid transport mechanisms in Drosophila.
authors.affiliation: Institute of Biomedical and Life Sciences, Division of Molecular Genetics, University of Glasgow, Glasgow G11 6NU, United Kingdom.
authors.forename: M R
authors.initials: MR
authors.lastname: MacPherson
authors.forename: V P
authors.initials: VP
authors.lastname: Pollock
authors.forename: K E
authors.initials: KE
authors.lastname: Broderick
authors.forename: L
authors.initials: L
authors.lastname: Kean
authors.forename: F C
authors.initials: FC
authors.lastname: O'Connell
authors.forename: J A
authors.initials: JA
authors.lastname: Dow
authors.forename: S A
authors.initials: SA
authors.lastname: Davies
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D006152:Cyclic GMP / Q000494:pharmacology; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019476:Insect Proteins / Q000187:drug effects / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007684:Kidney Tubules / Q000166:cytology / Q000378:metabolism*; D009479:Neuropeptides / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D009842:Oligopeptides / Q000187:drug effects / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D019284:Thapsigargin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: C112195:Ca-alpha1D protein, Drosophila; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D029721:Drosophila Proteins; D004791:Enzyme Inhibitors; D019476:Insect Proteins; D007473:Ion Channels; D009479:Neuropeptides; D009842:Oligopeptides; C472405:cac protein, Drosophila; C095817:cardioacceleratory peptide 2b; D019284:Thapsigargin; D014700:Verapamil; D006152:Cyclic GMP; D009543:Nifedipine; D002118:Calcium; D011761:Pyrrolidonecarboxylic Acid