Direct demonstration of insulin-like growth factor-I-induced nitric oxide production by endothelial cells.
Several lines of evidence indicate that insulin-like growth factor-I (IGF-I) is a potent mediator of vasodilation. To elucidate the mechanism and site of action of IGF-I, we performed continuous monitoring of nitric oxide (NO) release from endothelial cells using a highly-sensitive amperometric NO-sensor. Two types of cultured cells were used: human umbilical vein endothelial cells and immortalized rat renal interlobar artery endothelial cells. In separate experiments, [Ca2+]i changes in response to IGF-I were measured spectrofluorometrically in fura-2-loaded cells. Stimulation with IGF-I resulted in a rapid, dose-dependent increase in [NO] as detected by the NO-probe positioned 1 mm above the monolayers, followed by a sustained elevation lasting for at least five minutes. The effect of IGF-I was significantly suppressed by pretreatment with anti-IGF-I antibody, suggesting that it was specific for IGF-I. NG-nitro-L-arginine methyl ester, an inhibitor of NO synthesis, significantly blunted responses to IGF-I, but dexamethasone preincubation did not reduce the IGF-I-induced release of NO. These results indicate that the observed IGF-I-induced release of NO is a result of activation of the constitutive, rather than the inducible type of NO synthase in endothelial cells. Genistein, a tyrosine kinase inhibitor, resulted in a profound suppression of the IGF-I-induced release of NO. IGF-I did not affect [Ca2+]i in either type of cells. Therefore, IGF-I-induced NO production by both types of endothelial cells is mediated via a tyrosine kinase-dependent mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)
Tsukahara
H
H
Department of Medicine, State University of New York at Stony Brook.
Gordienko
D V
DV
Tonshoff
B
B
Gelato
M C
MC
Goligorsky
M S
MS
D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D000818:Animals; D001158:Arteries / Q000166:cytology / Q000378:metabolism; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase; D051381:Rats; D012079:Renal Circulation; D015398:Signal Transduction; D014471:Umbilical Veins / Q000166:cytology / Q000378:metabolism
D009569:Nitric Oxide; D007334:Insulin-Like Growth Factor I; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases