Morphological and functional changes of rabbit mesenteric artery cultured with fetal bovine serum

The aim of this study was to examine the morphological and functional chang es in rabbit mesenteric arterial tissue cultured with fetal bovine serum. I n the endothelium-denuded arteries cultured under a serum-free condition fo r one week (serum-free arteries), morphology of the smooth muscle layer was intact. In the serum-free arteries, high K+-induced contraction did not ch ange but norepinephrine-induced contraction slightly decreased compared wit h that in the freshly isolated arteries, whereas the sensitivity to these s timulants was significantly augmented. In the medial layer of the arteries cultured with 10% fetal bovine serum for one week (serum-treated arteries), proliferation, disorientation and death of smooth muscle cells were observ ed. In the serum-treated arteries, both the amplitude of contractions induc ed by high K+ and norepinephrine and the sensitivity to these stimulants we re significantly reduced compared with those of the serum-free arteries. Th e reduced norepinephrine-induced contraction in the serum-treated arteries was partially recovered by adding NG-monomethyl-L-arginine (L-NMMA), a nitr ic oxide (NO) synthase inhibitor, to the assay medium. In ol-toxin permeabi lized arteries, the amplitude of Ca2+-induced contraction and the sensitivi ty of the contractile apparatus to Ca2+ were significantly reduced after se rum-treatment. These results suggest that chronic serum-treatment of rabbit mesenteric arteries impairs muscle contractility by the morphological and phenotypic changes in smooth muscle cells. NO production in smooth muscle c ells is also responsible for the decreased contractility after the serum-tr eatment. (C) 2000 Elsevier Science Inc. All rights reserved.