Imaging Intracellular Calcium Signals In Intact Kidney Tissue

Calcium (Ca 2+ ) is an intracellular secondary messenger with multiple important physiological roles; disturbances in intracellular Ca 2+ homeostasis have been implicated in the pathogenesis of various kidney diseases. We have recently demonstrated that multiphoton microscopy can be used to image a range of intracellular signals in ex vivo rat kidney preparations such as tissue slices [1, 2] and isolated perfused organs [3]. Here, we demonstrate that the tissue slice model can be used to load established Ca 2+ indicators into both tubular and endothelial cells in the kidney. Kidney slices (200 μm thick) were obtained from adult, male sprague dawley rat kidneys (following cervical dislocation) and maintained in a physiological saline solution, bubbled with 95% O 2 /5% CO 2 . Loading of exogenous Ca 2+ sensitive dyes (Fluo4, Rhod‐2, Fura Red) was achieved ex vivo by using a re‐circulating perfusion system. Confocal microscopy was used to image Ca 2+ loading in the renal medulla, and to record changes in signal in response to physiological stimuli, i.e. ATP, Angiotensin II. We believe that the application of these imaging techniques have much potential to enhance understanding of the roles of intracellular Ca 2+ signalling in renal physiology and pathophysiology. Research supported by the Medical Research Council