Sequential Study of Plasma Euglobulin Fibrinolytic Activity during the Normal Menstrual Cycle and in Women on Oral Contraceptives Low in Estrogen

Abstract

Determinations of plasma euglobulin fibrinolytic activity were made in samples of plasma collected during one normal or hormone-simulated cycle in 15 young, normal women and in 11 women using an oral contraceptive low in estrogen. Distinct, individual levels caused the variations of fibrinolytic activity to be larger within the group than individually, and the activity showed only small changes during the cycle. The hormone group showed a marked increase in fibrinolytic activity with distinct fluctuations related to the phase of the cycle. This increase corresponded to that previously reported to be caused by oral contraceptives containing higher concentrations of estrogen.

The Diurnal Increase in Euglobulin Fibrinolytic Activity in Women Using Oral Contraceptives and in Normal Women, and the Generation of Intrinsic Fibrinolytic Activity

“…Patients and Blood Samples Assessed were.samples collected from two previously studied groups of healthy, informed volunteers (2,18). Women in the tirst groupln - 11, age 2l-30 y) had for 4 months or more used a combined OC with 30 pg ethinyl oestradiol and 150 pg levo-norgestrel daily for 2L days per cycle commencing at day 7.…”

“…A pool of normal human plasma (citrate) kept below -20" C served as reference material. Samplings were divided into five periods (1)(2)(3)(4)(5), which in the normal group covered days l-3,5-7,12-L6, L9-23, and 27-30 (prior to menstruation), respectively. In the hormone group the tive periods were: the first three days after onset of bleeding, the two days prior to resumption of hormone consumption (period 2), and three samplings separated by 7 days during the period of hormone consumption (periods 3 , 4, and 5).…”

“…Complete resolution of the frozen plasma samples was secured by placing the vials for 5 min in a waterbath at 37" C before transferring them to ice-water (2). The normal plasma euglobulin fraction (NEF) was then prepared at pH 5.9 from L0 times diluted plasma and redissolved as previously described (12,19) keeping the resuspended euglobulin suspension for at least 2 min at 37" C prior to application on the fibrin plate to secure complete resolution (2,20). The fibrinolytic activities of 30 pl drops were then determined on plasminogen-rich bovine fibrin plates (12).…”

“…3 The relationship between measured, extrinsic (tissue-type) plasminogen activator (t-PA) activity and normal euglobulin activity NEF (, -14S) in the morning (O) and in the evening (A) duringthe menstrual cycle, yielding the respective calculated equations: log y : 1.1 log x * 0.23 (marked a) and log y : 0.66lo9 x + 1.08 (marked b). Proportionality line: marked c. Blood samples were collected at selected times (periods [1][2][3][4][5]. Abscissa and ordinale: fibrinolytic activity in mm2 (logarithmic scale).…”

“…resulting fibrinolytic activity (EF) and the t-PA activity were then determined (Fig.5A). The concentrations of added t-PA varied from 0.78% to 100% with I00% t-PA corresponding to about7.5 international t-PA units ml-l, yielding the u.tiuiti"rl-n 2) shown in Fig. 5B.…”