Calcification of pericardial tissue pretreated with different amino acids.

Since the development of cardiac prostheses, numerous chemical treatments have been assayed to prevent the process of their mineralization. The effect of chemical treatment with amino acids is assessed in a subcutaneous implantation model in rats. Pericardial tissue from young calves was treated with L-lysine, L-glutamine, L-arginine or L-glutamic acid, each at a concentration of 0.5 M, following treatment with 0.625% glutaraldehyde. Then, the tissue was implanted into young rats for periods of 21 and 60 d, after which the calcium accumulated was quantified by atomic absorption spectroscopy. Values similar to or higher than those found in control samples indicated a lack of effectiveness of these treatments. Only in the 21-d implantation samples treated with L-lysine and L-arginine was less calcium accumulated than in the control tissue. After 60 d of implantation, all groups showed high levels of calcium deposition. The values obtained after 60 d of subcutaneous implantation were 87.5 +/- 52.4 mg Ca2+ per g dry weight of tissue for L-lysine, 108.7 +/- 43.5 mg Ca2+ per g dry weight of tissue for L-glutamine, 130.4 +/- 22.4 mg Ca2+ per g dry weight of tissue for L-glutamic acid, 119.3 +/- 27.6 mg Ca2+ per g dry weight of tissue for L-arginine and 100.0 +/- 38.3 mg Ca2+ per g dry weight of tissue for the control group. Treatment with amino acids does not appear to prevent the calcification of cardiac bioprostheses or of collagen-based biomaterials when assayed in a model of subcutaneous implantation.