Plasma
prostanoids and levels of
cyclic nucleotides were studied in forty-nine outpatients with precordial pains and subjected to the treadmill exercise test. Blood samples were drawn before, immediately after and 30 minutes after exercise, from antecubital veins. Plasma TXB2, 6-keto
PGF1 alpha,
cyclic AMP and
cyclic GMP levels were measured by radioimmunoassay. The results of exercise tests were evaluated according to the treadmill exercise score (
TES) of Hollenberg et al. Patients were divided into two groups; those with
TES (-) with ischemic findings in exercise and those with
TES (+) with normal exercise response. There were no differences in TXB2 levels between the two groups before exercise. Immediately after exercise statistically significant differences in TXB2 levels were present between the two groups. There were increased levels in the
TES (-) group and decreased levels in the
TES (+) group (p less than 0.01). Although the 6-keto
PGF1 alpha levels were the same between the two groups before exercise, 6-keto
PGF1 alpha levels in the
TES (+) group increased significantly immediately after exercise. Similar changes were noted in the case of
cyclic nucleotides, and the differences increased immediately after exercise. We conclude that high responses of
cyclic nucleotides and PGI2 are required to counteract increases in levels of TXA2 and diminution of these responses may be an important phenomenon involved in the physiological status of
ischemic heart disease.