Two-photon microscopy of albumin handling by the intact kidney (2007–2009)
The clinical association between protein loss in the urine and retention of salt, resulting in high blood pressure and progressive decline in kidney function, is well known. Under normal conditions, the kidneys filter 180 litres of water and reabsorb 1.7 kg of salt per day, a function which is principally performed by the kidney tubules in the kidney. Similarly the kidney tubule cells reabsorb and break down up to 3 grams of albumin per day. In the past, it has been considered that excessive protein loss in the urine is primarily due to problems in the filtering units of the kidneys, rather than due to abnormalities in the reabsorption of protein in the kidney tubules. However, we consider that common abnormalities in the processes within the kidney tubules that regulate both the reabsorption of salt and the excretion of acid may result in concomitant high blood pressure and increased protein loss in the kidney. Thus the overall aim of the project is to investigate the mechanisms by which the complex responsible for protein uptake determines the interrelationship between protein reabsorption and catabolism and the ion transporting proteins in the membrane of the proximal tubule.
This project will use cutting-edge microscopic imaging technology to investigate the mechanisms of protein uptake in the intact kidney. This information will be integrated with data obtained from our molecular physiology experiments to define how the kidney handles protein. As persistent proteinuria is the most important predictor of tubulointerstitial pathology and progressive decline in renal function in almost all renal disease, the understanding of the precise mechanism by which this occurs is essential in the design of renoprotective therapies.