Effect of endothelial cell-based iNOS gene transfer on cavernosal eNOS expression and mouse erectile responses

Abstract

Inducible nitric oxide synthase (iNOS) gene transfer is reported to augment erectile responses in rats, although it is also shown to impair vasorelaxation in cerebral arteries. We investigated the effect of endothelial cell-based iNOS gene transfer on endothelial NOS (eNOS) expression and mouse erectile responses. Human coronary artery endothelial cells (EC) transduced with empty vector (control) or iNOS were grown in culture and transplanted into the corpus cavernosum of severe combined immunodeficient mice. Endothelial NOS expression was compared in control and iNOS-transduced cells grown in the presence or absence of a selective iNOS inhibitor, L-N6-(1-iminoethyl) lysine hydrochloride (L-NIL). At 3-5 days after cell transplantation, we recorded intracorporal pressure (ICP) responses to cavernosal nerve stimulation and measured cavernosal total NO and eNOS protein expression. In this study, EC transduced with iNOS produced significantly more NO than controls but exhibited a twofold downregulation of eNOS protein and mRNA. This effect was reversed by L-NIL. In vivo, the cell-based gene transfer of iNOS led to significantly increased ICP responses, compared to mice transplanted with control ECs. Consistent with the in vitro data, cavernosal lysates had significantly reduced eNOS expression. In conclusion, EC gene transfer of iNOS downregulates EC expression of eNOS by an NOS-dependent mechanism. In the cavernosum of mice transplanted with Inos-transduced EC, nerve-stimulated erectile responses were augmented by the short-term gene transfer. However, our findings suggest that iNOS gene transfer may have deleterious effects on endothelial function if used as a treatment for erectile dysfunction.

Rosiglitazone Affects Nitric Oxide Synthases and Improves Renal Outcome in a Rat Model of Severe Ischemia/Reperfusion Injury

“…In the present study, the expression of eNOS is reduced in I/R injury [6, 7]. The overexpression of iNOS and the inflammatory response may result in a reduced expression of eNOS [21, 30]. Consequently, the iNOS upregulation most likely contributes to eNOS reduction in the present model as well.…”

“…Increased expression of iNOS plays a key role in cytotoxicity by inflammation response, necrosis, and apoptosis (Figure 7). Moreover, increased iNOS expression is described to reduce eNOS expression [21, 30]. Reduced eNOS expression impairs vascular function and renal perfusion.…”