Nitric oxide synthase inhibitors attenuate transforming-growth-factor-beta 1-stimulated capillary organization in vitro

Am J Pathol. 1997 May;150(5):1835-44.

Abstract

Angiogenesis is a complex process involving endothelial cell (EC) proliferation, migration, differentiation, and organization into patent capillary networks. Nitric oxide (NO), an EC mediator, has been reported to be antigenic as well as proangiogenic in different models of in vivo angiogenesis. Our aim was to investigate the role of NO in capillary organization using rat microvascular ECs (RFCs) grown in three-dimensional (3D) collagen gels. RFCs placed in 3D cultures exhibited extensive tube formation in the presence of transforming growth factor-beta 1. Addition of the NO synthase (NOS) inhibitors L-nitro-arginine methylester (L-NAME, 1 mmol/L) or L-monomethyl-nitro-l-arginine (1 mmol/L) inhibited tube formation and the accumulation of nitrite in the media by approximately 50%. Incubation of the 3D cultures with excess L-arginine reversed the inhibitory effect of L-NAME on tube formation. In contrast to the results obtained in 3D cultures, inhibition of NO synthesis by L-NAME did not influence RFC proliferation in two-dimensional (2D) cultures or antagonize the ability of transforming growth factor-beta 1 to suppress EC proliferation in 2D cultures. Reverse transcriptase-polymerase chain reaction revealed the constitutive expression of all three NOS isoforms, neuronal, inducible, and endothelial NOSs, in 2D and 3D cultures. Moreover, Western blot analysis demonstrated the presence of immunoreactive protein for all NOS isoforms in 3D cultures of RFCs. In addition, in the face of NOS blockade, co-treatment with the NO donor sodium nitroprusside or the stable analog of cGMP, 8-bromo-cGMP, restored capillary tube formation. Thus, the autocrine production of NO and the activation of soluble guanylate cyclase are necessary events in the process of differentiation and in vitro capillary tube organization of RFCs.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adipose Tissue
  • Animals
  • Capillaries / drug effects
  • Capillaries / physiology
  • Cell Differentiation / drug effects
  • Cell Division / drug effects
  • Cells, Cultured
  • Collagen
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / drug effects*
  • Endothelium, Vascular / physiology
  • Epididymis
  • Gels
  • Male
  • Neovascularization, Physiologic / drug effects*
  • Neovascularization, Physiologic / physiology
  • Nitric Oxide / metabolism
  • Nitric Oxide / physiology
  • Nitric Oxide Synthase / antagonists & inhibitors*
  • Nitric Oxide Synthase / biosynthesis
  • Nitric Oxide Synthase / genetics
  • Nitric Oxide Synthase / physiology
  • RNA, Messenger / biosynthesis
  • Rats
  • Transforming Growth Factor beta / pharmacology*

Substances

  • Gels
  • RNA, Messenger
  • Transforming Growth Factor beta
  • Nitric Oxide
  • Collagen
  • Nitric Oxide Synthase