Effect of Wall Tension on DNA and Protein Synthesis in Bovine Mesenteric Arteries in Vitro

Abstract: The aim of this investigation was to study the effect of wall tension and calcium antagonists on DNA and protein synthesis in bovine mesenteric arteries in vitro. The wall tension of the bovine mesenteric arteries was raised by stretching the vessel wall perpendicular to the length axis of the vessel. DNA and protein synthesis were determined by measuring incorporation of ³H-thymidine into DNA and incorporation of ¹⁴C-leucine into protein respectively. Elevating the wall tension from 0.05 N to 0.5 N significantly increased ³H-thymidine incorporation and ¹⁴C-leucine incorporation after an incubation period of 3 hr. Stretch had no effect on the distribution of ³H-thymidine. The distribution of ¹⁴C-leucine was increased by stretch in regular medium and to a less extent in calcium-free medium, which suggest that stretch stimulates the membrane transport of ¹⁴C-leucine. When the tension was increased from 0.05 N to 0.5 N for 10 min. before the incubation with ³H-thymidine, no effect was found. One μM nifedipine or felodipine inhibited the increase in ³H-thymidine incorporation caused by stretching, while no effect was found on ¹⁴C-leucine incorporation. In calcium-free medium, stretch-induced DNA synthesis was completely abolished. ¹⁴C-Leucine incorporation was impaired in calcium-free medium but the stretch-induced increse still remained. The results suggest that mechanical force may play an important role in DNA synthesis and protein metabolism of vascular smooth muscle.