Tissue collection.
For tissue collection, rats were anesthetized with isoflurane in 1 L/min oxygen. A midline laparotomy was performed, and the abdominal aorta was cannulated with PE-10 tubing (427400; Becton Dickinson) to flush both kidneys with Ringer solution (NaCl, 132 mM; KCl, 4.6 mM; MgSO