Adrenomedullin and nitric oxide inhibit human endothelial cell apoptosis via a cyclic GMP-independent mechanism.
Adrenomedullin, which was discovered as a vasodilating peptide, has been reported to be produced in various organs, in which adrenomedullin regulates not only vascular tone but also cell proliferation and differentiation in an autocrine/paracrine manner. We evaluated the effect of adrenomedullin on endothelial cell apoptosis. Human umbilical vein endothelial cells underwent apoptosis when cultured in serum-free medium. Treatment with adrenomedullin reduced the number of cells with pyknotic nuclei (Hoechst 33258 staining) and inhibited cell death (dimethylthiazol-diphenyltetrazolium bromide assay) in a dose-dependent manner. The administration of adrenomedullin did not alter the expression levels of Bcl-2 family proteins. Experiments with analogs of cAMP or a cAMP-elevating agonist demonstrated that elevation of the intracellular cAMP concentration does not mediate the antiapoptotic effect of adrenomedullin. The coadministration of N-nitro-L-arginine methyl ester (2 mmol/L), an inhibitor of nitric oxide synthase, abrogated the effect of adrenomedullin. Lower doses of sodium nitroprusside (1 to 10 micromol/L), a nitric oxide donor, mimicked the antiapoptotic effect of adrenomedullin. The antiapoptotic effect of sodium nitroprusside was not attenuated by the inhibition of soluble guanylyl cyclase with 1 micromol/L oxadiazolo-quinoxalin-1-one nor could apoptosis be inhibited by the incubation of human umbilical vein endothelial cells with 1 mmol/L 8-bromo-cGMP, a cell-permeant cGMP analog. These results indicate that adrenomedullin and nitric oxide inhibit endothelial cell apoptosis via a cGMP-independent mechanism.
Sata
M
M
Department of Internal Medicine, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Kakoki
M
M
Nagata
D
D
Nishimatsu
H
H
Suzuki
E
E
Aoyagi
T
T
Sugiura
S
S
Kojima
H
H
Nagano
T
T
Kangawa
K
K
Matsuo
H
H
Omata
M
M
Nagai
R
R
Hirata
Y
Y
D053607:Adrenomedullin; D017209:Apoptosis / Q000187:drug effects*; D002470:Cell Survival; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000502:physiology; D006152:Cyclic GMP / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D009569:Nitric Oxide / Q000502:physiology*; D010455:Peptides / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis
D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D053607:Adrenomedullin; D009569:Nitric Oxide; D000242:Cyclic AMP; D006152:Cyclic GMP