Loss of size selectivity of the glomerular filtration barrier in rats following laparotomy and muscle trauma.
Posttraumatic microalbuminuria may be caused by either charge- or size-selective alterations in the glomerular filtration barrier, or both, and/or to a reduction in proximal tubular protein reabsorption. This study was performed to elucidate the pathophysiology of the increases in glomerular permeability occurring in rats exposed to a laparotomy or to a laparotomy and muscle trauma. In anesthetized Wistar rats (250-280 g), the left ureter was cannulated for urine collection, while simultaneously blood access was achieved. Rats were exposed to trauma by a laparotomy (L; n = 8), or by a combination of L and muscle trauma (MT; L+MT) induced by topical blunt injury of the abdominal muscles bilaterally. After L, muscles were crushed using hemostatic forceps at either 2 x 2 sites ("small" MT; n = 9), or at 2 x 5 sites ("large" MT; n = 9). Sham groups (n = 16), not exposed to a laparotomy, were used as controls. The glomerular sieving coefficients (theta) to polydisperse FITC-Ficoll-70/400 (molecular radius 13-80 A) were determined at 5 or 60 min after L and L+MT, respectively, from plasma and urine samples, and analyzed by high-performance size-exclusion chromatography. A tissue-uptake technique was used to assess theta for (125)I-labeled serum albumin. L, with or without MT, increased theta for Ficoll(55-80A) and albumin rapidly and markedly. Theta-Ficoll(70A) thus increased approximately threefold, and theta for albumin significantly, for all trauma groups. According to the "two-pore model" of glomerular permeability, these changes mainly reflect an increase in the number of large pores in the glomerular filter without any primary changes in the charge-selective properties of the filter.
Axelsson
Josefin
J
Department of Nephrology, University Hospital of Lund, Lund, Sweden.
Mahmutovic
Irma
I
Rippe
Anna
A
Rippe
Bengt
B
D000009:Abdominal Muscles / Q000293:injuries*; D000419:Albuminuria / Q000378:metabolism* / Q000503:physiopathology; D000818:Animals; D001794:Blood Pressure; D002199:Capillary Permeability; D062109:Dermatologic Surgical Procedures; D004195:Disease Models, Animal; D005362:Ficoll / Q000031:analogs & derivatives / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000378:metabolism; D005919:Glomerular Filtration Rate; D006339:Heart Rate; D007457:Iodine Radioisotopes; D007678:Kidney Glomerulus / Q000098:blood supply / Q000378:metabolism* / Q000503:physiopathology; D007813:Laparotomy; D008297:Male; D008954:Models, Biological; D008970:Molecular Weight; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000378:metabolism; D013997:Time Factors; D014949:Wounds, Nonpenetrating / Q000378:metabolism* / Q000503:physiopathology
D007457:Iodine Radioisotopes; D012709:Serum Albumin; C045540:fluorescein 5-isothiocyanate-Ficoll; D005362:Ficoll; D016650:Fluorescein-5-isothiocyanate