Kidney dysfunction in the arthritic rat

Kidney function and histopathology were investigated in the adjuvant-induced arthritic rat. Rats injected with Mycobacterium butyricum exhibited symptoms of arthritis (i.e. paw edema and loss of body weight) by day 9 which worsened and included systemic manifestations of the disease on days 16 and 30. Definite signs of kidney dysfunction were observed by day 16 which included elevated urine output and plasma creatinine values and decreased creatinine clearance. By day 30, these parameters were similar to the values obtained from normal rats; however, kidney weights from arthritic rats than those from normal rats. Histopathologic abnormalities observed in the kidneys of arthritic rats on day 30 included tubular lesions consisting of focal basophilia, edema, granular deposits and basement membrane thickening. Changes in the glomerulus included granular deposits with focal glomerulopathy. These findings are the first to clearly demonstrate kidney dysfunction and histopathologic alterations associated with the early expression of the adjuvant-induced disease process in the rat. Our observations in the rat suggest that renal dysfunction in man can be mediated by the inflammatory disease process and is not solely a drug treatment-induced side effect.