Figure 4: Fractions isolated by density gradient from the parasite culture have different ability to remove ET-1. Parasite culture (D10 strain) where density separated by Percoll/sorbitol gradient. Each fraction was incubated with synthetic ET-1 (2.5 fmol/mL) for 24 hours and, at end of the incubation, ET-1 was determined by ELISA. Recovery of ET-1 incubated in: medium (empty bar); RBC separated by different density and age (subdivided in young, medium and old) (dotted bars); pRBC at the trophozoite stage (4–8% parasitemia) (striped bar); fraction containing HZ (black bar). Results represent the mean ± SD from three different experiments. 07 HZ versus control; 38 pRBC versus control.