Vasodilatory effects of antivascular endothelium growth factor (VEGF) antibody, corticosteroid, and nitric oxide on the posterior ciliary arteries.

PURPOSE

The purpose of this study was to determine whether an antivascular endothelium growth factor (VEGF) antibody, a corticosteroid, and sodium nitroprusside (SNP) [a nitric oxide (NO) donor] are possible treatment agents for nonarteritic ischemic optic neuropathy (NAION) by clarifying their effects on high-K (potassium) solution-induced contraction in isolated rabbit and human posterior ciliary arteries (PCA).

METHODS

Vascular ring segments were cut from the distal section of the PCA and mounted in a double-myograph system. After obtaining the maximal contraction following the administration of high-K solution, bevacizumab as an anti-VEGF antibody, methylprednisolone as a corticosteroid, and SNP were administered separately. When a vasodilatory effect was observed, carboxy-PTIO (a NO scavenger) or L-NAME (a NO synthase inhibitor) was administered.

RESULTS

Bevacizumab did not relax either the rabbit or the human PCA, whereas methylprednisolone relaxed both. Neither carboxy-PTIO nor L-NAME inhibited methylprednisolone-induced relaxation. SNP relaxed the rabbit PCA. Carboxy-PTIO inhibited SNP-induced relaxation, but L-NAME did not. In the human PCA, the vasodilatory effect of SNP was present, but weaker than in the rabbit PCA.

CONCLUSIONS

A corticosteroid has NO-independent vasodilatory effects. Exogenous NO has a weak dilating effect in the human PCA. Therefore, corticosteroid could be effective for the treatment of NAION.