ABSTRACT
An increase in the incidence of thromboembolic disorders has been associated with oral contraceptive use, though the causative mechanisms remain unclear. Our studies indicate that the contraceptive steroids, irrespective of the intermediary metabolic processes involved, cause changes in the surface charge characteristics of the blood vessel wall and blood cells in the following cases: (i) in experiments using dogs, the hormonal steroids result in a greater reduction in the pore surface charge of veins than in arteries; (ii) in rats, the current induced mesenteric occlusion times are significantly lowered following administration of combined contraceptives steroids; (iii) in humans, the electrophoretic mobilities of erythrocytes and platelets from women taking Ovral and Demulen are lower than in controls, and (iv) there is no significant alteration of plasma coagulation times of women who are on injectable progestin therapy. Demulen and Ovral appear to result in a slight decrease in activated partial thromboplastin times compared to controls.
PIP: The effects of hormonal contraceptive agents on the vascular system were studied in rats, dogs, and 34 women taking oral or injectable steroid contraceptive agents. Changes in the surface charge characteristics of the blood vessel wall and blood cells were observed. In dogs, the reduction in pore surface charge was greater in veins than in arteries. In rats, the induced mesenteric occlusion times were significantly reduced (p less than .001). However, Provera did not significantly reduce induced occlusion time in these animals (p greater than .01). Ov ral and Demulen lowered the mobilities of erythrocytes and platelets in women. Plasma coagulation times were not markedly altered in women receiving injectable progestin. Acitivated partial thromboplastin times were slightly decreased by Ovral and Demulen. The results suggest an increased tendency toward thrombosis in women taking steroid hormone contraceptive agents.
