Microassay of cyclic nucleotides in vessel wall. V. Simultaneous assay of cyclic AMP and cyclic GMP

Antiaggregative aspirin dosage at the affected vessel wall

The present study, using patients with Takayasu's disease (pulseless disease), characterized by segmentally affected arterial lesions and stenotic conditions with a nonspecific inflammatory morbid condition, was designed to assess whether or not a low dose of aspirin can practically exert its preventive effect against the aggregation of platelets that have just passed along a rough-surfaced arterial wall. Twenty Japanese women with Takayasu's disease were selected under the following criteria: A unilateral upper extremity was angiographically confirmed to be affected with the disease, while the contralateral limb was almost normal. Systolic blood pressure on the affected side was almost half that on the nonaffected side. The patients showed neither a positive CRP nor an accentuated ESR. In these patients, mean plasma levels of TXB2 and 3 microM ADP-induced platelet aggregation in blood obtained from the affected side were 156.5 +/- 17.7 pg/ml, and 59.5 +/- 6.0%, respectively, which were significantly high as compared with 104.5 +/- 17.6 and 41.7 +/- 8.8%, respectively, in samples from the nonaffected side. Forty and eighty mg of aspirin per day administered to two randomly composed groups, respectively, showed an improvement in platelet aggregability and TXB2 levels on the nonaffected side. In the affected limbs, though 80 mg/day led to significant decreases in TXB2 levels (108.0 +/- 7.8 pg/ml, p less than 0.05) and platelet aggregability (21.3 +/- 7.6%), the 40-mg regimen showed no significant reductions (134.6 +/- 9.4 pg/ml, 35.6 +/- 17.1%). Plasma levels of 6-keto PGF1 alpha revealed no differences between 40- and 80-mg regimens, or between before and after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

A study of the mechanism of estrogen as an antiatherosclerotic: the inhibitory effect of estrogen on A23187-induced contraction of the aortic wall

Although the antiatherosclerotic effects of estrogen are well known, the mechanisms involved have not been determined. We designed experiments in which strips of thoracic aorta from oophorectomized rabbits were contracted by the calcium ionophore A23187 and the inhibition of the contraction by estrogen and concomitant levels of cyclic nucleotides were determined. A23187 (10(-5) M) increased the tension slowly but progressively, and there was a concomitant decrease in cyclic AMP levels. While a dose-dependent relaxation occurred in strips contracted by A23187 with addition of theophylline (greater than 10(-4) M) or dibutyryl cyclic AMP (greater than 10(-4) M) to the bath, prior addition of these compounds inhibited the contraction. Pretreatment of the strips with estrogen (2 x 1-(-7) M, 2 x 10(-5) M) significantly prevented contraction of the strips, as induced by A23187, and also prevented reduction in cyclic AMP levels, as induced by the ionophore. Cyclic GMP levels remained unchanged throughout. As the contraction of these tissues wall was inhibited by estrogen in an apparent association with a reduction in the levels of cyclic AMP, this might help to explain the antiatherosclerotic effects of estrogen, as reduction in these nucleotide levels has been suggested to induce atherosclerotic lesions in the arterial wall by enhancing vascular permeability.