PubMed · 1512989
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O Mohara, Y Masuyama. 1992. [Non-modulating essential hypertension].. https://pubmed.ncbi.nlm.nih.gov/1512989/
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Many previous studies have demonstrated that angiotensin II (AII) type I (ATI) receptor antagonists remarkably reduced intimal lesions in rats following balloon injury. Using vascular smooth muscle cells (VSMC) in culture, we tested the hypothesis that other classical growth factors may enhance AII effects on VSMC growth, and ATI receptor antagonists may inhibit these effects. AII, platelet-derived growth factor-BB (PDGF-BB), and epidermal growth factor (EGF) caused a 3426 +/- 262%, 277 +/- 69%, and 1568 +/- 62% increase in [3H]thymidine incorporation in VSMC (mean +/- SD, n = 3), respectively. The exposure of the cells to AII in combination with PDGF-BB or EGF resulted in an approximately 2-fold or 1.5-fold elevation of the AII-dependent effect, respectively. 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimi dazole-7- carboxylic acid (CV-11974), the active metabolite of the specific nonpeptide AT1 receptor antagonist (+/-)-1-cyclohexyloxycarbonyloxy)ethyl 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimi dazole- 7-carboxylate (TCV-116, Candesartan), suppressed the effect of AII down to basal values, as well as reducing the synergistic effect of PDGF or the additive effect of EGF on AII-induced [3H]thymidine incorporation. AII and PDGF-BB per se induced 57 +/- 19 and 70 +/- 14% increase in VSMC number. Combination of both agonists resulted in a 2-fold increase of the AII effect on cell number. Again, CV-11974 blocked the effect of AII, as well as the additive effect of PDGF-BB on cell number. From these findings, it may be concluded that AT1 receptor antagonists may reduce or prevent the development of intimal lesions following vascular injury through inhibition of direct and indirect growth-promoting effects of AII in VSMC.
Angiotensin II (Ang II) stimulates norepinephrine transporter (NET) and tyrosine hydroxylase (TH) in the neurons, but the signal transduction mechanism of this neuromodulation is not understood. Treatment of neuronal cultures of hypothalamus-brainstem with Ang II resulted in a time- and dose-dependent activation of Ras, Raf-1, and mitogen-activated protein kinase. This activation was mediated by the interaction of Ang II with the AT1, receptor subtype and was associated with the redistribution of AT1 receptor with Ras and Raf-1 on the neuronal membrane. Treatment with antisense oligonucleotide (AON) to mitogen-activated protein kinase decreased mitogen-activated protein kinase immunoreactivity by 70% and attenuated Ang II stimulation of c-fos, NET, and TH mRNA levels. This demonstrates that induction of these genes requires mitogen-activated protein kinase activation by Ang II. In contrast, AON to mitogen-activated protein kinase failed to inhibit Ang II stimulation of plasminogen activator inhibitor-1 mRNA levels. These results suggest that AT1 receptors are coupled to a Ras-Raf-1 mitogen-activated protein kinase signal transduction pathway that is responsible for stimulation of NET and TH, two neuro-modulatory actions of Ang II in the brain.
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