PROSTACYCLIN AND THROMBOXANE IN PREGNANT AND NONPREGNANT WOMEN IN RESPONSE TO EXERCISE

Objectives: To compare the effects of a 30-minute standardized submaximal exercise test on the urinary excretion of the metabolites of prostacyclin and thromboxane A(2) in healthy pregnant and nonpregnant women. Methods: Time-fixed urine samples were collected before, during, and after the exercise test from nine pregnant and six nonpregnant women, and the samples were assayed for 6-keto-prostaglandin (PG) F-1 alpha and 2,3-dinor-6-keto-PGF(1 alpha) (prostacyclin metabolites), as well as for thromboxane B-2 and 2,3-dinor-thromboxane B-2 (thromboxane A(2) metabolites) by high-pressure liquid chromatography and radioimmunoassay. Results: Pregnancy itself was associated with a 3.6-4.3-fold rise in prostacyclin excretion, but with no significant change in thromboxane output. The exercise caused stimulation in both prostacyclin and thromboxane excretion. In response to exercise, the maximal rise in 6-keto-PGF(1 alpha) output was significantly larger among the pregnant subjects, but when compared with its pre-exercise excretion on a relative percentage scale, the range of rise in 6-keto-PGF(1 alpha) output (58-73%) was comparable in pregnant and nonpregnant subjects. Furthermore, excretion of 2,3-dinor-6-keto-PGF(1 alpha) rose similarly in the two study groups (68-166%) in response to exercise. The exercise caused a 2.3-fold rise in the output of thromboxane B-2 excretion in both pregnant and nonpregnant women, but it stimulated (by a twofold rise) the excretion of 2,3-dinor-thromboxane B-2 only in pregnant women. Conclusion: Physical activity may stimulate vasoactive prostacyclin and thromboxane excretion during pregnancy. Such changes may play a role in the regulation of blood now during exercise.