In the study rat aortae were perfused by endothelin in vitro and the RNA samplewas extracted from them for Northern blotting in which c-myc and hsp70 gene probes were labeled by α-32P-dCTP,The results on the bands of autoradiographs show that c-myc and hsp70 gene expression increases in the rat aortae. It might play an important role on proliferation of vascular smooth muscle cells in hypertension and atherosclerosis.