# The Vasomotor Impact of Cu/ZnSODs Is Higher in Arterial Smooth Muscle of Early Postnatal Rats Compared to Adult Animals

## TL;DR

This study shows that Cu/ZnSODs have a stronger effect on blood vessel contraction in young rats compared to adults, and this effect is regulated by endothelial NO in early life.

## Contribution

The study reveals a novel age-dependent role of Cu/ZnSODs in vascular contraction and their interaction with endothelial NO in early postnatal rats.

## Key findings

- Cu/ZnSOD activity and SOD3 protein levels are higher in young rat arteries compared to adults.
- Cu/ZnSOD inhibition reduces contraction in endothelium-denuded young arteries but not in adults.
- Endothelial NO counteracts the contractile effect of Cu/ZnSODs in early postnatal arteries.

## Abstract

The mechanisms of vascular tone regulation during early postnatal ontogenesis differ considerably from those in adulthood. We tested the hypothesis that the vasomotor influence of superoxide dismutases is higher in arteries of rats shortly after birth compared to adult animals. Saphenous arteries of 10 to 15 day (“young”) and 3 to 4 month (“adult”) old rats were studied using quantitative PCR, spectrophotometry, Western blotting, and isometric myography. Sod3 mRNA was most abundant in both adult and young saphenous arteries. Total SOD activity, Cu/ZnSODs activity, and SOD3 protein content were higher in young compared to adult arteries. H2O2 caused vessel contraction, while elimination of H2O2 weakened contractile responses of endothelium-denuded young arteries. The Cu/ZnSOD inhibitor DETC had no influence on contraction of adult arteries, but weakened contraction of endothelium-denuded, but not endothelium-intact arteries of young rats. The latter effect was observed in the presence of the NO-synthase inhibitor L-NNA, but not with the soluble guanylate cyclase inhibitor ODQ. DETC had no effect in the presence of sodium nitroprusside. Thus, Cu/ZnSODs promote contraction of saphenous arteries in the early postnatal period, but not in adult age. This influence of Cu/ZnSODs is counteracted by endothelial NO in early postnatal arteries.