Cyclo‐oxygenase‐2 inhibition and endothelium‐dependent vasodilation in younger vs. older healthy adults

Aim

A major feature of endothelial dysfunction is reduced endothelium‐dependent vasodilation, which in ageing may be due to decreased production of endothelial prostacyclin, or nitric oxide (NO), or both.

Method

We tested this hypothesis in 12 younger (age 18–38 years, six women) and 12 older healthy adults (age 55–73 years, six post‐menopausal women). Endothelium‐dependent vasodilation was assessed by the forearm vascular conductance (FVC) response to intra‐arterial acetylcholine (ACh) (0.5, 1.0, 2.0, 4.0 μg dl⁻¹ forearm tissue min⁻¹) before and 90 min after inhibition of the enzyme cyclo‐oxygenase‐2 (COX‐2) with oral celecoxib (400 mg), followed by the addition of endothelial NO synthase inhibition with intra‐arterial N^G‐monomethyl‐l arginine acetate (L‐NMMA).

Results

Ageing was associated with a significantly reduced FVC response to ACh (P = 0.009, age‐by‐dose interaction; highest dose FVC ± SEM in ageing: 11.2 ± 1.4 vs. younger: 17.7 ± 2.4 units, P = 0.02). Celecoxib did not reduce resting FVC or the responses to ACh in any group. L‐NMMA significantly reduced resting FVC and the responses to ACh in all groups, and absolute FVC values following L‐NMMA were similar between groups.

Conclusion

In healthy normotensive younger and older adults, there is minimal contribution of prostacyclin to ACh‐mediated vasodilation, yet the NO component of vasodilation is reduced with ageing. In the clinical context, these findings suggest that acute administration of medications that inhibit prostacyclin (i.e. COX‐2 inhibitors) evoke modest vascular consequences in healthy persons. Additional studies are necessary to test whether chronic use of COX‐2 medications reduces endothelium dependent vasodilation in older persons with or without cardiovascular risk factors.

DOI: 10.1111/bcp.12397

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