Resolution of the insect ouabain paradox.
Many insects are highly resistant to plant toxins, such as the cardiac glycoside ouabain. How can the epithelia that must handle such toxins, also be refractory to them? In Drosophila, the Malpighian (renal) tubule contains large amounts of Na(+),K(+) ATPase that is known biochemically to be exquisitely sensitive to ouabain, yet the intact tissue is almost unaffected by even extraordinary concentrations. The explanation is that the tubules are protected by an active ouabain transport system, colocated with the Na(+),K(+) ATPase, thus preventing ouabain from reaching inhibitory concentrations within the basolateral infoldings of principal cells. These data show that the Na(+),K(+) ATPase, previously thought to be unimportant, may be as vital in insect tissues as in vertebrates, but can be cryptic to conventional pharmacology.
Torrie
Leah S
LS
Division of Molecular Genetics, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, Scotland, United Kingdom.
Radford
Jonathan C
JC
Southall
Tony D
TD
Kean
Laura
L
Dinsmore
Andrew J
AJ
Davies
Shireen A
SA
Dow
Julian A T
JA
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004331:Drosophila melanogaster / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D008317:Malpighian Tubules / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D027361:Organic Anion Transporters / Q000235:genetics / Q000378:metabolism*; D010042:Ouabain / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D010802:Phylogeny; D034622:RNA Interference; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D027361:Organic Anion Transporters; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase