Oxalate crystal deposits in the heart in chronic renal failure: an experimental study.

The present study was undertaken to evaluate three factors which may contribute to the myocardial deposition of calcium oxalate in 5/6 nephrectomised rats: (1) increased plasma oxalate, (2) elevated plasma ionised calcium, and (3) local myocardial tissue damage. A simple increase in plasma oxalate concentrations produced by injection of sodium oxalate did not cause deposits in the heart. Increased plasma ionised calcium combined with elevated plasma oxalate for 60 days was likewise unimportant with regard to cardiac deposits. However, when local tissue damage was added by heterotopic cardiac transplantation, deposition of crystals was seen in four or five allografts damaged by rejection. In this model the rat's own heart was not affected. Although an increase in plasma oxalate values is not without significance, the present findings suggest that local tissue damage is a more important factor in the myocardial deposition of oxalate crystals in renal failure.