In Vivo Measurement of Thromboxane B2 and 6-Keto-Prostaglandin Fi. in Humans in Response to a Standardized Vascular Injury and the Influence of Aspirin

The eifects of smoking, aspirin ingestion, and sex differences on bleeding times and bleeding time thromboxane B2 and 6-keto-prostaglandin (PG)Fia production were examined. Nonsmok-ing men produced more thromboxane B2 (3.99±0.76 ng/ml) than nonsmokingwomen (2.13±0.24 ng/ml). Female smokers produced more thromboxane B2 (5.01±0.97 ng/ml) than nonsmoking women. Twenty-four hours after a single dose of 600 mg aspirin, in vitro production of thromboxane B2 in response to collagen fell by 95%, whereas in vivo production of thromboxane B2 and 6-keto-PGF,a in bleeding time blood fell by 87 % and 66%, respectively. Subjects with the lowest absolute levels of thromboxane B2 24 hours after aspirin were also those with the longest postaspirin bleeding times. Recovery of 6-keto-PGFla production was faster than recovery of thromboxane B2 production, but 6-keto-PGFI, production for most subjects was still below basal 72 hours after aspirin. The influence of two different doses of long-term aspirin (80 mg every other day and 325 mg daily) on the in vivo production of thromboxane B2 and 6-keto-PGFl. was studied in normals and diabetics. After 14 days of 80 mg aspirin every other day, thromboxane B2 and 6-keto-PGFIa production were both substantially inhibited (93 % and 78%, respectively). After 14 days of 325 mg aspirin daily, thromboxane B2 production wa