Recently, we have shown that erythrocytes obtained from patients with
chronic renal failure (CRF) exhibited an increased rate of
ATP formation from
adenine as a substrate. Thus, we concluded that this process was in part responsible for the increase of
adenine nucleotide concentration in uremic erythrocytes. There cannot be excluded however, that a decreased rate of adenylate degradation is an additional mechanism responsible for the elevated
ATP concentration. To test this hypothesis, in this paper we compared the rate of
adenine nucleotide breakdown in the erythrocytes obtained from patients with CRF and from healthy subjects. Using HPLC technique, we evaluated: (1)
hypoxanthine production by uremic RBC incubated in incubation medium: (a) pH 7.4 containing 1.2 mM
phosphate (which mimics physiological conditions) and (b) pH 7.1 containing 2.4 mM
phosphate (which mimics uremic conditions); (2)
adenine nucleotide degradation (
IMP,
inosine,
adenosine,
hypoxanthine production) by uremic RBC incubated in the presence of iodoacetate (glycolysis inhibitor) and
EHNA (
adenosine deaminase inhibitor). The erythrocytes of healthy volunteers served as control. The obtained results indicate that
adenine nucleotide catabolism measured as a
hypoxanthine formation was much faster in erythrocytes of patients with CRF than in the cells of healthy subjects. This phenomenon was observed both in the erythrocytes incubated at pH 7.4 in the medium containing 1.2 mM
inorganic phosphate and in the medium which mimics
hyperphosphatemia (2.4 mM) and
metabolic acidosis (pH 7.1). The experiments with
EHNA indicated that
adenine nucleotide degradation proceeded via
AMP-
IMP-
Inosine-
Hypoxanthine pathway in erythrocytes of both patients with CRF and healthy subjects. Iodoacetate caused a several fold stimulation of adenylate breakdown. Under these conditions: (a) the rate of
AMP catabolites (
IMP +
inosine +
adenosine +
hypoxanthine) formation was substantially higher in the erythrocytes from patients with CRF; (b) in erythrocytes of healthy subjects degradation of
AMP proceeded via
IMP and via
adenosine essentially at the same rate; (c) in erythrocytes of patients with CRF the rate of
AMP degradation via
IMP was about 2 fold greater than via
adenosine. The results presented in this paper suggest that
adenine nucleotide degradation is markedly accelerated in erythrocytes of patients with CRF.