Abstract
The authors have reported that when the patients with ischemic heart disease (IHD) were loaded with isometric exercise, platelet sensitivity to ADP-aggregation and plasma von Willebrand factor (vWF) level increased. In this paper, influence of isometric exercise on plasma β-thromboglobulin (β-TG) level was investigated.
MATERIALS AND METHODS: Eleven patients with IHD (Table 1), none of them were in acute stage, and their age-and sex-matched healthy controls were loaded with handgrip isometric exercise of 50% maximal contraction using a Smedley's handgrip dynamometer for 2 minutes. Plasma β-thromboglobulin level, platelet sensitivity to ADP-aggregation and plasma vWF level were measured before and immediately after exercise and the values were compared statistically with a paired comparison procedure. Plasma β-TG was measured using β-TG Ria kit (The Radiochemical Centre, England). Platelet sensitivity was measured using a original method to detect microscopically the highest dilution (n) of serially two-fold diluted ADP solution (2-nmg/ml) to give platelet aggregation. When the endpoint was 2-10mg/ml, for example, the sensitivity was expressed as 10. Plasma vWF was also tested using a original device. The maximal dilution (n) of the serially two-fold diluted test plasma (1:2n) to give ristocetin-induced platelet aggregation was detected microscopically and n was defined as plasma vWF titer.
RESULTS (Fig. 1): 1) IHD: In 8 patients plasma β-TG level increased after exercise and the change was significant (p<0.05) (before exercise 58.0±17.71, after exercise 70.4±21.21). Platelets were aggregated even by 2 to 4 times diluted ADP after exercise and platelet sensitivity increased significantly (P<0.05) (bef. 9.8±0.32, aft. 10.4±0.34). Plasma vWF titer also increased significantly (p<0.05) after exercise (bef. 5.0±0.19, aft. 5.6±0.19). 2) Controls: No significant changes.
COMMENT: The results suggest that isometric exercise may induce in vivo activation and release reaction of platelets in IHD patients. It might be attributable to a forced passage of platelets through stenotic portion of atherosclerotic coronary vessel during isometric exercise.
