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 A2 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) F1 alpha and 2,3-dinor-6-keto-PGF1 alpha (prostacyclin metabolites), as well as for thromboxane B2 and 2,3-dinor-thromboxane B2 (thromboxane A2 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-PGF1 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-PGF1 alpha output (58-73%) was comparable in pregnant and nonpregnant subjects. Furthermore, excretion of 2,3-dinor-6-keto-PGF1 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 B2 excretion in both pregnant and nonpregnant women, but it stimulated (by a twofold rise) the excretion of 2,3-dinor-thromboxane B2 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 flow during exercise.