In vivo microvascular clearance of albumin in renal and extrarenal tissues in puromycin aminonucleoside (PAN) induced nephrotic syndrome

integrity outside the renal vasculature would contribute to the oedema formation in the PAN nephrotic Background. The nephrotic syndrome is characterized by generalized oedema considered to be due to the fall syndrome. in serum albumin and to sodium retention. The aim of the present study was to investigate whether a generalized disturbance in vascular integrity contrib- Introduction utes to the oedema formation. Methods. We used the PAN-(puromycin aminonucleo- The integrity of vascular endothelium is of paramount side) nephritis model in order to induce the nephrotic importance to maintain and regulate intravascular syndrome in female Wistar rats. Eight rats were given volume and to control fluid and macromolecular PAN, 15 mg/100 g body weight, intraperitoneally 10 exchange between the intra- and extravascular fluid days prior to the study, whereas 21 rats served as compartments. In glomerulonephritis the permselectivcontrols. Albumin clearance to tissues was measured ity of the glomerular capillaries is severely deranged. using a dual isotope technique. Repeated blood When advanced, heavy urinary protein losses ensue, samples as well as samples from various muscles, leading to a fall in plasma albumin, and hence, in kidney, liver, lung, heart, abdominal wall and from plasma oncotic pressure (COP p ). Traditionally, the ascites fluid were taken to determine radioactivity and pathogenesis of the generalized oedema seen in the tissue dry-to-wet weights. Clearance of albumin (Cl alb ) nephrotic syndrome is thought to be due to the reducfrom plasma to interstitium was calculated from the tion of COP p causing an altered Starling fluid equilib( linear) increment in ‘plasma equivalent tissue albumin rium and a redistribution of fluid from plasma to space’ as a function of time, corrected for intravascular interstitium. According to this concept, intravascular volume and oedema. The plasma and urine concentra- volume is contracted, leading to the activation of the tions of albumin were determined in a parallel study renin‐angiotensin‐aldosterone system and to vasopresby single radial diVusion using monospecific rabbit sin release, and to a secondary state of sodium retenanti-rat antiserum in seven PAN animals and 13 tion. Peripheral oedema would then just be the logical controls.