Influence of ageing on vasomotor responses of human epicardial coronary arteries.

Vasomotor responses to various agonists were studied on isolated circular segments of human epicardial coronary arteries from three different age groups; 23-38 years, 40-58 years and 63-86 years. Noradrenaline had no or only weak contractile effect on coronary arteries from younger patients but induced contraction of all artery segments from older patients. The Emax value was significantly (P<0.0001) higher in arteries from the oldest group compared to each of the two younger age groups, whereas the potency was similar in all three groups. Linear regression analysis of noradrenaline-induced contraction in individual patients revealed a significantly positive age-correlation (correlation coefficient 0.67, P<0.0001). Contraction induced by endothelin-1 and relaxation induced by substance P, calcitonin gene-related peptide and vasoactive intestinal peptide on arteries precontracted with U46619 showed no significant differences in maximum responses and potencies between the three age groups, and no significant linear age-correlation. These data demonstrate a large variability in contractile responses to noradrenaline with contractions seen mostly in coronary arteries from older patients. It thus seems that sympathetic activation could contribute to coronary ischaemia in some patients.