title: Treatment with the vascular disrupting agent combretastatin is associated with impaired AQP2 trafficking and increased urine output.
abstract: Combretastatin A-4 disodium phosphate (CA4P) is a vascular disrupting agent known to mediate its effects primarily on tumor blood vessels. CA4P has previously been shown to induce a significant increase in mean arterial blood pressure and in hemoglobin concentration in mice. In the present study, we examined whether this is associated with a general leakage of water into certain tissues or with changes in renal water handling. Munich-Wistar rats received either CA4P (30 mg/kg body wt) or saline intraperitoneally as a bolus injection. One hour later, hemoglobin concentration and mean blood pressure increased significantly. MRI showed no significant changes in tissue water content following CA4P administration. However, urine output and salt excretion increased 1 h after CA4P treatment, without changes in urinary and medullary osmolality. Aquaporin 2 (AQP2) mRNA levels in kidney inner medulla did not change 1 h after CA4P treatment, but semiquantitative confocal laser-scanning microscopy analysis demonstrated a decrease in phosphorylated AQP2 (pS256-AQP2) apical distribution within the collecting ducts of CA4P-treated rats compared with the characteristic apical localization in control rats. Furthermore, we demonstrated that CA4P cause disruption of microtubules and a weaker apical labeling of pS256-AQP2 in collecting duct principal cells within 1 h. In conclusion, our data indicate that water escapes from the vascular system after CA4P treatment, and it may take place primarily through a renal mechanism. The CA4P-mediated increase in urine output seems to be a local effect in the collecting ducts due to reduced AQP2 trafficking to the apical plasma membrane.
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, Nørrebrogade, Denmark. anja@mr.au.dk
authors.forename: Anja B
authors.initials: AB
authors.lastname: Bohn
authors.forename: Rikke
authors.initials: R
authors.lastname: Nørregaard
authors.forename: Lene
authors.initials: L
authors.lastname: Stødkilde
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Lotte B
authors.initials: LB
authors.lastname: Bertelsen
authors.forename: Robert A
authors.initials: RA
authors.lastname: Fenton
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Matchkov
authors.forename: Elena V
authors.initials: EV
authors.lastname: Bouzinova
authors.forename: Michael R
authors.initials: MR
authors.lastname: Horsman
authors.forename: Jørgen
authors.initials: J
authors.lastname: Frøkiær
authors.forename: Hans
authors.initials: H
authors.lastname: Stødkilde-Jørgensen
mesh_terms: D000818:Animals; D051399:Aquaporin 2 / Q000378:metabolism*; D001632:Bibenzyls / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000378:metabolism / Q000473:pathology; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D050257:Tubulin Modulators / Q000494:pharmacology; D014554:Urination / Q000187:drug effects* / Q000502:physiology
chemical_list: C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D001632:Bibenzyls; D006454:Hemoglobins; D050257:Tubulin Modulators; C040105:combretastatin