title: Fluorescence isolation of mouse late distal convoluted tubules and connecting tubules: effects of vasopressin and vitamin D3 on Ca2+ signaling.
abstract: The renal late distal convoluted tubules and connecting tubules are sites for the fine regulation of Na(+) and Ca(2+) reabsorption. The role of these segments in Na(+) and K(+) homeostasis is possibly underestimated, as the tubules are technically difficult to isolate in sufficient numbers and purity for functional analysis. To overcome these difficulties, we have developed a transgenic mouse model expressing enhanced green fluorescent protein in late distal convoluted tubules and connecting tubules. Enhanced green fluorescent protein expression was driven by the promoter for the transient receptor potential subfamily V, member 5. Confocal fluorescence microscopy allowed detection of enhanced green fluorescent protein in living, isolated late distal convoluted tubules and connecting tubules and in the initial cortical collecting ducts. Enhanced green fluorescent protein expression was validated by double- and triple-fluorescence immunolabeling with specific tubule markers. Freshly isolated late distal convoluted tubules and connecting tubules increased their intracellular Ca(2+) levels in response to the V(2) receptor-specific agonist deamino-Cys,d-Arg(8)-vasopressin (2 x 10(-10) M) after 1 min of superfusion. In addition, both late distal convoluted tubules and connecting tubules displayed a concentration-dependent intracellular Ca(2+) response to 1alpha,25-dihydroxyvitamin D(3) (range 10(-10) to 10(-8) M). This suggests that 1alpha,25-dihydroxyvitamin D(3) can act through a nongenomic signaling pathway in these tubules. In conclusion, the transgenic mouse model, expressing enhanced green fluorescent protein, is suitable for rapid isolation of viable late distal convoluted tubules, connecting tubules, and initial cortical collecting ducts and provides an ideal tool for a more exhaustive functional characterization of these segments.
authors.affiliation: Institute of Anatomy and The Water and Salt Research Center, Univ. of Aarhus, Wilhelm Meyers Allé, Bldg. 1-234, 8000 Aarhus C, Denmark. mvho@ana.au.dk
authors.forename: Marlene V
authors.initials: MV
authors.lastname: Hofmeister
authors.forename: Robert A
authors.initials: RA
authors.lastname: Fenton
authors.forename: Jeppe
authors.initials: J
authors.lastname: Praetorius
mesh_terms: D000818:Animals; D050034:Antidiuretic Agents / Q000494:pharmacology; D002118:Calcium / Q000652:urine; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002762:Cholecalciferol / Q000494:pharmacology*; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007686:Kidney Tubules, Distal / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D023421:Models, Animal; D011188:Potassium / Q000652:urine; D012964:Sodium / Q000652:urine; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism; D014667:Vasopressins / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology
chemical_list: D050034:Antidiuretic Agents; D015220:Calcium Channels; D050916:TRPV Cation Channels; C492240:Trpv5 protein, mouse; D014815:Vitamins; D014667:Vasopressins; D049452:Green Fluorescent Proteins; D002762:Cholecalciferol; D012964:Sodium; D011188:Potassium; D002118:Calcium