Suppression of 3H-lysine incorporation into the vascular non-collagenous protein in rats treated with estradiol-17 beta.

The in vivo incorporation of 3H-lysine into non-collagenous protein of the heart, aorta and mesenteric arteries was measured in castrated or non-castrated male young rats given hormone treatment once daily for 14 consecutive days. In rats given estradiol-17 beta (50 micrograms), a significant reduction of blood pressure was noted at 7 and 8 weeks of age. The lysine incorporation into non-collagenous protein was markedly decreased in mesenteric arteries and to a lesser extent in the aorta of rats treated with estradiol-17 beta (50 micrograms). The decline in blood pressure concomitant with the reduction of lysine incorporation into non-collagenous protein of the same vessels was of similar magnitude in castrated, testosterone (50 micrograms) plus estradiol-17 beta (50 micrograms)-treated rats as compared with that in castrated testosterone-treated (50 micrograms) animals. Despite the variety of hormone treatments, the incorporation of 3H-lysine into non-collagenous protein of heart was similar for all the rats examined. It is suggested that the suppressive effect of estradiol-17 beta on biosynthesis of vascular non-collagenous protein, especially in small arteries, plays an important role in lowering the blood pressure of young male rats.