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A B S T R A C T Previous workers have shown that metabolic acidosis increases the apparent space through which administered bicarbonate is distributed. This finding has been ascribed to the accompanying acidemia and to the consequent availability of a large quantity of hydrogen ion that accumulates on nonbicarbonate tissue buffers during the development of acidosis. To test this hypothesis, bicarbonate space was measured in dogs with a broad range of steady-state plasma [HCO-] in association with alkalemia as well as with acidemia. Appropriate combinations of pH and plasma [HCO-] were achieved by pretreating the animals to produce graded degrees of each of the four cardinal, chronic acid-base disorders. Metabolic acidosis (n = 15) was produced by prolonged HCI-feeding; metabolic alkalosis (n = 17) by diuretics and a chloride-free diet; and respiratory acidosis (n = 9) and alkalosis (n = 8) by means of an environmental chamber. Animals with normal acid-base status (n = 4) were also studied. Sodium bicarbonate (5 mmol/kg) was infused over 10 min to the unanesthetized animals; observations were carried out over 90 min.

Although the presence in the recipient of preformed antibodies to HLA antigens in the kidney of a renal-transplant donor may be associated with early graft failure, such grafts are often well tolerated. We have investigated the possibility that anti-anti-HLA (antiidiotypic) antibodies influence the outcome of renal transplantation in recipients with a history of presensitization to their donor's HLA antigens. A retrospective analysis of 20 such cases showed that in 10 patients the transplanted kidney was rejected within one month, whereas in the remaining 10 the graft was tolerated for more than a year. Nine of the 10 patients in whom the graft was tolerated had anti-anti-HLA antibodies at the time of transplantation. Nine of the 10 patients in whom the graft was rejected had antibodies that potentiated, rather than blocked, the cytotoxic activity of anti-donor-HLA antibodies. These results suggest that patients with anti-anti-HLA antibodies specific for a potential donor can safely undergo transplantation, despite a prior history of anti-HLA antibodies. At the time of transplantation, patients who have antibodies that potentiate the cytotoxic activity of a historically positive serum are at high risk of graft rejection within a short period. Taking these considerations into account may improve the reliability of cross-matching in renal transplantation.