Repeated toxic injury of peritoneum: accumulation of toxicity and adaptation to injury.

In order to develop new methods for the study of pathogenesis of post-injury fibroplasia, a rat model of chemical peritonitis was explored. Sodium hypochlorite (NaOCl) of various concentrations was injected intraperitoneally one or more times using different intervals between doses. Some time later, the surface fibrosis of liver, spleen, omentum and other abdominal organs was evaluated. A dose-response relation at intermediate concentrations and an apparent threshold at low concentrations were observed. Fibroplasia was increased by repeated doses (accumulation) but it was ameliorated compared to the same total amount of chemical given as a single injection (adaptation during repeated dosing). The rapid disappearance of the chemical irritant and the large size and easy accessibility of the peritoneal cavity suggest that this model may be useful in further study of chemical toxicity and fibroplasia in relation to human fibrosing diseases and injuries (trauma, surgery, peritoneal dialysis). The model has the unique feature of evaluating the morphological effects of the toxic injury and secondary functional effects at the same time.