In order to search the changes of response between vascular wall and platelets, plasma thromboxane (TXB2), cyclic AMP, cyclic GMP levels and platelet aggregation were measured during exercise in 31 patients with the complaint of chest pain. The exercise was performed by submaximal treadmill test and blood samples were collected before, immediately and 30min. after test.
Using Hollenberg's treadmill exercise score (TES), 15patients were judged as TES (-) group (positive in conventional test) and others as TES (+) group (negative test). At the immediately after exercise, plasma levels of TXB2 in TES (-) group were 208.5±20.8pg/ml, a statistically high level as compared with 168.6±14.4pg/ml, in TES (+) group. On the other hand, in TES (+) group levels of cAMP and cGMP (cAMP; 14.5±0.7, cGMP; 5.37±0.46pmol/ml) increased significantly immediately after exercise, as compared with these in TES (-) group (11.3+0.8, 4.44±0.48pmol/ml). No significant changes of platelet aggregation was seen in both TES (+), TES (-) groups, except that induced by adrenaline. In TES (-) group, maximum aggregation rate induced by adrenaline immediately after exercise was 66.5±5. 8%, a statistically high as compared with 45.5±8.2% before exercise. There was a positive correlation between TXB2 and cAMP in TES (+) group during exercise, however, such a correlation was not found in TES (-) group.
These data suggest that the poor response of vascular wall for hemodynamic changes exists in patients of coronary heart disease which breaks the exquisite balance of the interrelationship between platelet and vascular wall.