Functional endothelin-1 receptors in rat astrocytoma C6.

Rat astrocytoma C6 cells have been recently identified as target cells for ET-1, which stimulates inositol lipid turnover in these cells. It is shown here that binding of ET-1 to high-affinity receptors on C6 cells leads to 40-45% inhibition of isoproterenol-induced intracellular cyclic AMP accumulation, as well as to stimulation of inositol lipid turnover, both effects characterized by an absolute requirement of extracellular calcium. Moreover, ET-1, which has been generally reported to have a mitogenic effect on a variety of target cells including primary rat astrocytes, is shown here to stimulate or, alternatively, inhibit DNA synthesis in C6 cells, depending on the subclone considered.