EFFECTS OF PSYCHOSOCIAL STRESS ON ENDOTHELIUM-MEDIATED DILATION OF ATHEROSCLEROTIC ARTERIES IN CYNOMOLGUS MONKEYS

The objectives of this study were to determine if psychosocial stress impairs dilation through endothelium-derived relaxing factor (EDRF)-me diated mechanisms and if this effect is long lasting. Monkeys were fed an atherogenic diet for 36 mo while in one of three experimental cond itions: (a) stable social groups (''unstressed,'' n = 6); (b) unstable social groups for the first half of the experiment and stable groups for the second half (''early stress,'' n = 8); and (c) stable groups f or the first half of the experiment and unstable groups for the second half (''late stress,'' n = 6). Iliac arteries were studied in organ c hambers containing Krebs' buffer and 10(-6) M indomethacin. Arteries f rom the late stress group had impaired dilation (shift of the dose-res ponse curve down and to the right) to acetylcholine and the calcium io nophore A23187 (for both, P < 0.05), but not to nitroprusside (P > 0.0 5), compared with unstressed or early stress monkeys. N(G)-methyl-L-ar ginine reduced the dose-response curve to both acetylcholine and A2318 7 in the unstressed group and resulted in similar vascular responses a mong all three groups (P > 0.05). We conclude that current, but not pr evious, exposure to chronic stress impairs endothelium-mediated dilati on of atherosclerotic iliac arteries of cynomolgus monkeys through an EDRF-mediated mechanism.