The broad interest of the Peti-Peterdi lab is renal (patho)physiology, specifically the intrarenal mechanisms involved in the control of blood pressure and body fluid balance under normal and disease conditions (hypertension, diabetes). For example we study the function of juxtaglomerular apparatus (JGA), a major structural component of the renin-angiotensin system in the kidney, and one of the most important regulatory sites of renal salt & water conservation and blood pressure maintenance. The process of glomerular filtrate formation and regulation of renal hemodynamics, including the tubuloglomerular feedback (TGF) mechanism and renin release, involves the complex interaction of a number of different cell types of the JGA. Current research is focusing on signaling from the tubular component of JGA, a specialized epithelial cell plaque called macula densa (MD). MD cells act as sensor cells detecting changes in luminal variables (salt concentration, tubular fluid flow, metabolic factors, etc.) and sending signals to underlying vascular smooth muscle cells and renin producing granular cells of the afferent arteriole. These signaling processes involve the release of various chemical mediator substances from the MD and their interaction with specific receptors in the JGA ultimately resulting in vasoconstriction and renin exocytosis. Our laboratory is renowned for the application of a specific imaging approach, optical sectioning of the intact living kidney with high spatial and temporal resolution using multiphoton fluorescence microscopy. Quantitative imaging of certain cell types, the basic renal functional parameters and their alterations is performed in a number of animal disease models including hypertension, diabetes, and glomerulosclerosis.