Model organisms: new insights into ion channel and transporter function. L-type calcium channels regulate epithelial fluid transport in Drosophila melanogaster.
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.
MacPherson
M R
MR
Institute of Biomedical and Life Sciences, Division of Molecular Genetics, University of Glasgow, Glasgow G11 6NU, United Kingdom.
Pollock
V P
VP
Broderick
K E
KE
Kean
L
L
O'Connell
F C
FC
Dow
J A
JA
Davies
S A
SA
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
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