Abstract 026: Three-dimensional Visualization And Evaluation Of Differences In Renin Expression In Kidneys Exposed In Vivo To Either Low Or High Arterial Pressure

Abstract

Background: Renin cells are essential for the regulation of blood pressure (BP). In adult mammals, renin cells are present in small numbers in the juxtaglomerular area, but when homeostasis is threatened, such as by hypotension, additional cells along the renal arterioles are recruited to synthesize and release renin. However, there have been no studies to date that have shown changes in the distribution of renin cells in response to changes in BP by three-dimensional (3D) imaging. Objective: Establish a method to visualize and measure renin cells, and comparison of renin expression differences in kidneys exposed to hypo- or hypertension in 3D. Methods: We used our new mouse model ( Ren1 c-tdTomato ) that expresses renin and the fluorescent tdTomato under the control of the endogenous renin gene environment. To test whether we could detect differences in the distribution of renin in response to changes in BP, we subjected Ren1 c-tdTomato mice to aortic coarctation at 3 months of life. The right and left kidneys (RK, LK) are exposed to high and low BPs, respectively. We harvested kidneys after 72 hours and performed tissue-clearing. We used light sheet microscopy for imaging and the Imaris software for 3D reconstruction and data analysis. We defined the 3D renin cell index (3D-RI) as total volume of renin cells (μm 3 ) divided by total number of glomeruli. We extracted 10 cubes of 500 μm square each from the L and R renal cortex, calculated their individual 3D-RI and compared them. Results: With tissue-clearing-based 3D imaging, renin cells were clearly visualized, allowing observation of their distribution and appearance at a one-cell resolution. In the LK exposed to hypotension, several afferent arterioles were identified where renin cells extended close to their branching point. Further, the average value of the 3D-RI was significantly higher in LK (21460 ±6303) than in RK (12838 ± 4632; p = 0.003). Conclusion: Using our new Ren1 c-tdTomato mouse and 3D imaging technology we detected differences in renin cells appearance and distribution in kidneys exposed to hypo- or hypertension. Combined with spatial single cell multiomics, 3D visualization of renin cells will open new avenues for understanding how vascular cells acquire their positional identity in health and disease.