The platelet thromboxane A2 synthesizing activity in type II diabetes mellitus was studied by stimulating the washed platelets with either arachidonic acid or thrombin, and by measuring the amoutn of TBX2 synthesized during the stimulation. In the poorly contolled diabetic state, the mean activity was elevated. The individual activities were not corelated to fasting plasma glucose (Fig. 1). By treating the diabetic state, the activities that were above the average before treatment tended to decrease, while the reverse was true for those that were below the average. The inverse correlation was noted fairly strongly between the pretreatment activities and their changes during treatment (Fig. 2). This finding indicated that the thromboxane A2 synthesizing activity was under the negative feedback control mechanism, and the mechanism was operating probably at the level of cyclooxygenase, since the same correlations were noted on arachidonic acid as well as thrombin stimulation. The changes in the activities during treatment were not related to the changes in the mean platelet volume. In our study, the changes in activities were measured at near-normoglycemic state, which might resulted in observing the above-discribed control mechanism.
