The Role of eNOS Phosphorylation in Causing Drug-induced Vascular Injury

Abstract

Previously we found that regulation of eNOS is an important part of the pathogenic process of Drug-induced vascular injury (DIVI) for PDE4i. The aims of the current study were to examine the phosphorylation of eNOS in mesentery versus aorta at known regulatory sites across DIVIinducing drug classes and to compare changes across species. We found that phosphorylation at S615 in rats was elevated 35-fold 2 hr after the last dose of CI-1044 in mesentery versus 3-fold in aorta. Immunoprecipitation studies revealed that many of the upstream regulators of eNOS activation were associated with eNOS in 1 or more signalosome complexes. Next rats were treated with drugs from 4 other classes known to cause DIVI. Each drug was given alone and in combination with SIN-1 (NO donor) or L-NAME (eNOS inhibitor), and the level of eNOS phosphorylation in mesentery and aorta tissue was correlated with the extent of vascular injury and measured serum nitrite. Drugs or combinations produced altered serum nitrite levels as well as vascular injury score in the mesentery. The results suggested that phosphorylation of S615 may be associated with DIVI activity. Studies with the species-specific A2A adenosine agonist CI-947 in rats versus primates showed a similar pattern.

Safety issues of compounds acting on adenosinergic signalling

“…Single‐dose rat study (150 μg/kg) revealed myocardial necrosis with several foci together with perivascular and ventricular oedema, whereas during repeated dose study (30 μg/kg per 4 days) fibrotic heart tissue has developed . Mechanisms of cardiovascular toxicity still remain uncertain but appear to be partly related to excessive induction of endothelial nitric oxide synthase . It was also suggested from multiple sources that some antidepressants (citalopram, amitriptyline) may cause QRS/QT prolongation activating A 1 AdRs.…”

“…[119] Mechanisms of cardiovascular toxicity still remain uncertain but appear to be partly related to excessive induction of endothelial nitric oxide synthase. [120] It was also suggested from multiple sources that some antidepressants (citalopram, amitriptyline) may cause QRS/QT prolongation activating A 1 AdRs. Cardiovascular toxicity was reversed, when AdR antagonists were employed.…”

An in vivo and in vitro study

“…Serum nitrite: The measurement of serum nitrite was performed using the total nitric oxide (NO) assay (R&D Systems, Minneapolis, Minnesota, USA) according to the manufacturer's instructions. The (30), and high-Danshen group (30). Each group mice has three endings: A, B, and C. The A ending: mice were intravenously administered Danshen or saline five times, at 0, 24, 48, 72, and 96 h respectively.…”

Scientific and Regulatory Policy Committee Points-to-consider Paper*

“…A unifying feature in common with these proposed mechanisms is the observation of high production of NO within tissues after exposure to many compounds producing vascular effects. Many drugs also have signaling pathways that can pass through endothelial nitric oxide synthase (eNOS), and modulation of NO production can affect lesion severity (Tobin et al 2014).…”