“…In CNS, ET-l and ET-3 can be synthesized in neurons (Fuxe et al, 1991;Krsmanovic et al, 1991;Lysko et al, 1991), glial (MacCumber et al, 1990Hösli and Hösli, 1991), and endothelial (Vigne et al, 1990;Yoshimoto et al, 1990) cells, and all these cells exhibit high-affinity binding sites for these peptides. In glial cells, ET can act as a growth factor stimulating DNA synthesis In peripheral tissues, such as vascular smooth muscle cells (Wikles et al, 1993), iris sphincter smooth muscles (Zhang and Abdel-Latif, 1992), osteoblast cells (Suzuki et al, 1994), mesangial cells (Kester et a!., 1992), aorta (Liu et al, 1992), and fibroblasts (MacNulty et al, 1990), ET can also stimulate phospholipase D (PLD). Such an effect appears to occur as well in CNS (Ambar and Sokolovsky, 1993;Sarri et a!., 1995).…”