Ageing is associated with reduced basal and stimulated release of nitric oxide by the coronary endothelium

The ageing process is known to be associated with biochemical and functional changes in the heart. In an attempt to determine whether the ability of the coronary endothelium to secrete nitric oxide (NO) both at rest and in response to pharmacological stimulation is age dependent, we studied four groups of rats of different ages (1, 5, 15 and 26 months, respectively). Basal release of NO by endothelium as assessed by response of coronary flow to L-monomethylarginine, an inhibitor of NO synthase, was higher in the younger age groups. Similarly, the response of coronary flow to 5-hydroxytryptamine, a selective probe of endothelial capacity to secrete NO, was diminished in the older animals. This was confirmed by direct measurement of NO by chemiluminescence in the coronary effluent. In contrast, the response to glyceryl trinitrate appeared to be unaltered by age. It is concluded that in rats, basal and stimulated release of nitric oxide by the coronary endothelium deteriorates with age.