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 × 2 sites (“small” MT; n = 9), or at 2 × 5 sites (“large” MT; n = 9). Sham groups (n = 16), not exposed to a laparotomy, were used as controls. The glomerular sieving coefficients (θ) to polydisperse FITC-Ficoll-70/400 (molecular radius 13–80 A)...