DYNAMICS OF CONNECTIVE MATRIX DEPOSITION IN ACUTE EXPERIMENTAL ESCHERICHIA-COLI PYELONEPHRITIS IN RATS

Adult male rats were subjected to pyelonephritis by direct kidney intr amedullary injection of 0.1 ml saline suspension of 10(5) E. coli. Ani mals were killed at intervals of 4, 10, 15, 30 and 60 days. Half of ea ch kidney and bladder were cultured in proper bacteriologic media to d emonstrate the existence of infection. The other halves were submitted to light microscopy and ultrastructural studies. Immunofluorescence m ethods were used for the study of connective matrix components, at the initial stage of the inflammatory process (4, 10 and 15 days). Infect ion was documented by bacteriologic, gross and microscopic findings in all groups following inoculation, and it lasted up to two months. Fol lowing the acute inflammatory reaction, fibronectin and type III colla gen were deposited in the interstitium of kidneys. Small amounts of ty pe I collagen were found later. Type IV collagen appeared in small qua ntities, associated with collapse of structures containing basement me mbranes. Fibronectin became concentrated in re-activated foci. The sub sequent scarring and associated focal renal atrophy depended upon the extension of the acute lesion.