Figure 3
Characterization of L-arginine influx in LPI monocytes. Normal and LPI monocytes, isolated as described in Methods, were washed in EBSS. Panel A. Arginine uptake was assayed by 1 min incubation in EBSS supplemented with L-[3H]-arginine (50 μM; 4 μCi/ml) in the absence (total uptake) or in the presence of leucine (2 mM) or leucine + lysine (both 2 mM) as indicated. For normal cells, data are means ± SEM of 9 independent experiments (n = 9 normal donors), each performed in quadruplicate. For the LPI patient, data are means ± SD of 4 determinations obtained in a representative experiment, repeated twice with comparable results. *** p < 0.001 vs total; NS, Not Significant vs +Leucine; ns, not significant vs total; # p < 0.05 vs +Leucine. Panel B. Arginine transport values of each subject (n = 9 normal donors; n = 2 determinations in the LPI patient) were employed to calculate system y+L and system y+ transport activity. System y+L: difference between total uptake and the uptake obtained in the presence of 2 mM leucine; system y+: difference between the influx measured in the presence of 2 mM leucine and that measured in the presence of 2 mM leucine + 2 mM lysine.