Issue 5, 2009January 21, 2010 Welcome to the fifth issue of Kidney and Blood Pressure Research Digest (KBPR Digest). We would again like to draw your attention to articles of outstanding importance in the field of nephrology and hypertension by presenting short summaries to the scientific community in the form of KBPR Digest. KBPR Digest provides readers from all over the world with a free and concise overview on interesting topics which are part of the current issue of Kidney and Blood Pressure Research. We hope that you will be inspired to get to know more about the details of the articles which are discussed below. Professor Thomas Quaschning, MD, PHD On behalf of the Editorial Board of Kidney and Blood Pressure Research mail@thomas-quaschning.de   Digest of issue 6/2009 Issue 6/2009 of Kidney and Blood Pressure Research covers a wide spectrum of both clinical and preclinical topics. It contains a study which explores the interplay between chronic kidney disease and the retinal microvasculature, as well as a comparison of clinical outcomes in patients with systemic lupus erythematodes on peritoneal dialysis versus hemodialysis. A third study examines the expression of aquaporin water channels in a model of renovascular hypertension. Microcirculation is defined by precapillary arterioles and small arteries, i.e. arteries with diameters < 350 micrometers. These vessels regulate the steep decline in blood pressure (BP). Vascular hypertrophy and arteriosclerotic changes in this part of the vasculature have been demonstrated to play a prognostic role for cardiovascular events. Recently, non-invasive retinal vessel analysis (RVA) has received increased attention. It is highly standardized by computer-assisted digital measurement of the ratio of retinal arteriolar and venular diameters (AVR) and has been evaluated in large-scale epidemiological studies. Additionally, several of these studies calculated renal function and observed that retinal microvascular abnormalities were associated with renal dysfunction. However, no study confirmed these epidemiological results in a cohort with chronic kidney disease (CKD). Performing RVA in CKD patients - as presented by Baumann and coworkers (Kidney Blood Press Res 2009;32:428-433) - may help to understand the link between renal insufficiency and elevated cerebrovascular risk. RVA was performed in 34 non-diabetic CKD patients and 33 age-matched volunteers with normal renal function. Retinal photographs were digitized, vascular lumen diameters measured and AVR was calculated. Office BP was measured and cardiovascular risk factors assessed. AVR was found to be lower in CKD patients as compared to age-matched volunteers. In particular, retinal arterioles were narrower in CKD patients as compared to volunteers. In CKD, estimated glomerular filtration rate, BP and renin-angiotensin system blocker independently predicted AVR. Moreover, retinal arteriolar diameter predicted renal function. In summary, this study showed for the first time that retinal vessels of non-diabetic patients with CKD are of smaller diameter than in age-matched volunteers without impairment of renal function. Interestingly, the retinal microvasculature additionally reflects renal function. Lupus nephritis is one of the major complications of systemic lupus erythematosus (SLE). Up to 22% of SLE patients with lupus nephritis eventually develop end-stage renal disease (ESRD) within 10 years of being diagnosed with lupus nephritis. Researchers generally agree that, after developing ESRD (which is a major cause of mortality and morbidity), SLE disease activities subside. Poor prognosis of SLE dialysis patients has been demonstrated, but so far clinical outcome has not distinguished between different dialysis modalities. In their retrospective study, a Taiwanese group of scientists (Kidney Blood Press Res 2009;32:451-456) evaluated the differences in clinical outcomes between peritoneal dialysis (PD) and hemodialysis (HD) in a population of female SLE patients with ESRD. Twenty-two female SLE patients undergoing PD were compared with 14 female SLE patients receiving HD. Clinical outcomes and infective complications were reviewed. The overall mortality rate was much higher in the PD group (6/22) than in the HD group (1/14) (p = 0.027). PD patients had higher C-reactive protein levels and elevated numbers of infectious episodes. Furthermore, HD patients had higher serum albumin levels before the end of the observation period. In conclusion, this study revealed that patients with lupus nephritis-related ESRD on PD have a higher all-cause mortality rate which may be related to their higher CRP, lower albumin and higher infection rate (excluding catheter- and AV-fistula-related infections) than those on HD. These preliminary study findings should be considered by nephrologists when selecting a dialysis modality for female SLE ESRD patients. It is well known that 2-kidney, 1-clip (2K1C) hypertension is primarily attributed to an increased peripheral vascular resistance by an increased level of angiotensin II. However, angiotensin II plays an important role in the regulation of rnal sodium and water handling as well as systemic vasoconstriction. In the kidney, aquaporin (AQP) water channels allow the movement of water across the tubular epithelium, whereas the renal sodium transporters play a critical role in the sodium reabsorption and regulation of extracellular fluid volume. Dysregulation of AQPs and sodium transporters have been implicated in various pathophysiological states associated with alterations of sodium and water balance, such as ischemic acute renal failure and angiotensin II induced hypertension. The aim of the present study of Ma and coworkers (Kidney Blood Press Res 2009;32:411-420) was to determine whether the renal regulation of AQP water channels and sodium transporters are altered in 2K1C hypertension. Therefore, male Sprague-Dawley rats were made 2K1C hypertensive for 1 week, and the renal expression of AQPs and sodium transporters was determined by semiquantitative immunoblotting and immunohistochemistry. Systolic blood pressure was increased in 2K1C rats. Experimental rats revealed impaired urinary concentration in association with increased urine volume. Urinary sodium excretion also increased. The expression of AQP1-3 was decreased in the clipped kidney compared with the control kidney, whereas it was unchanged in the non-clipped kidney. The expression of the Na-K-2Cl cotransporter and epithelial sodium channels were decreased in the clipped kidney, while remaining unchanged in the non-clipped kidney. In conclusion, dysregulation of AQPs and sodium transporters/channels may be considered to play a role in the pathogenesis of impaired sodium reabsorption and the urinary concentration defect, documented in 2K1C hypertension. © S. Karger AG - Medical and Scientific Publishers Allschwilerstrasse 10, P.O. Box, CH-4009 Basel (Switzerland) Tel. +41 61 306 1200, Fax +41 61 306 1234, publications@karger.com. Please read the Karger Privacy Policy. If you have received this email by mistake, click here and we will take you off this mailing list.