title: Multiple functions of Na/K-ATPase in dopamine-induced salivation of the Blacklegged tick, Ixodes scapularis.
abstract: Control of salivary secretion in ticks involves autocrine dopamine activating two dopamine receptors: D1 and Invertebrate-specific D1-like dopamine receptors. In this study, we investigated Na/K-ATPase as an important component of the secretory process. Immunoreactivity for Na/K-ATPase revealed basal infolding of lamellate cells in type-I, abluminal interstitial (epithelial) cells in type-II, and labyrinth-like infolding structures opening towards the lumen in type-III acini. Ouabain (10 μmol l(-1)), a specific inhibitor of Na/K-ATPase, abolished dopamine-induced salivary secretion by suppressing fluid transport in type III acini. At 1 μmol l(-1), ouabain, the secreted saliva was hyperosmotic. This suggests that ouabain also inhibits an ion resorptive function of Na/K-ATPase in the type I acini. Dopamine/ouabain were not involved in activation of protein secretion, while dopamine-induced saliva contained constitutively basal level of protein. We hypothesize that the dopamine-dependent primary saliva formation, mediated by Na/K-ATPase in type III and type II acini, is followed by a dopamine-independent resorptive function of Na/K-ATPase in type I acini located in the proximal end of the salivary duct.
authors: Department of Entomology, Kansas State University, 123 Waters Hall, Manhattan, KS 66506, USA.
authors: Donghun
authors: D
authors: Kim
authors: Department of Entomology, Kansas State University, 123 Waters Hall, Manhattan, KS 66506, USA.
authors: Joshua
authors: J
authors: Urban
authors: Division of Biology, Microscopy Facility, Kansas State University, Ackert Hall, Manhattan, Kansas 66506, USA.
authors: Daniel L
authors: DL
authors: Boyle
authors: Department of Entomology, Kansas State University, 123 Waters Hall, Manhattan, KS 66506, USA.
authors: Yoonseong
authors: Y
authors: Park
mesh_terms: D061354:Acinar Cells / Q000378:metabolism; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D018884:Ixodes / Q000502:physiology*; D010042:Ouabain / Q000494:pharmacology; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D012463:Saliva / Q000378:metabolism*; D018987:Salivary Ducts / Q000502:physiology; D012472:Salivation / Q000187:drug effects / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D017447:Receptors, Dopamine D1; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D004298:Dopamine