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

SummaryThe diurnal fluctuations in plasma euglobulin fibrinolytic activity in women on oral contraceptives and in normal women showed similar patterns of increase. Following inactivation of inhibitors by flufenamate the individual increases and the evening levels did not differ. The diurnal increase was related to an increase in extrinsic (tissue-type) plasminogen activator (t-PA) activity, which contributes little to the total activity of the euglobulin fraction but induces an activation of the intrinsic system.

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Inhibition of Tissue-Type Plasminogen Activator in Plasma of Women Using Oral Contraceptives and in Normal Women During a Menstrual Cycle

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661570 ◽

1986 ◽

Vol 55 (03) ◽

pp. 388-389 ◽

Cited By ~ 24

Author(s):

J Jespersen ◽

C Kluft

Keyword(s):

Menstrual Cycle ◽

Plasminogen Activator ◽

Oral Contraceptives ◽

Tissue Type ◽

Tissue Type Plasminogen Activator ◽

Type Plasminogen Activator ◽

Normal Women ◽

Ethinyl Oestradiol

SummaryTissue-type plasminogen activator (t-PA) inhibition in plasma was assessed in 15 normal women and in 10 women using oral contraceptives (OC) containing 30 μg ethinyl oestradiol and 150 μg levo-norgestrel. The levels of t-PA inhibition were significantly lower in the OC group with marked fluctuations related to the hormone cycle. Normal women had only minor fluctuations.

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Increased Euglobulin Fibrinolytic Potential in Women on Oral Contraceptives Low in Oestrogen – Levels of Extrinsic and Intrinsic Plasminogen Activators, Prekallikrein, Factor XII, and C1-Inactivator

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657871 ◽

1985 ◽

Vol 54 (02) ◽

pp. 454-459 ◽

Cited By ~ 42

Author(s):

Jørgen Jespersen ◽

Cornelis Kluft

Keyword(s):

Plasminogen Activator ◽

Oral Contraceptives ◽

Fibrinolytic Activity ◽

Tissue Type ◽

Factor Xii ◽

Type Plasminogen Activator ◽

The Difference ◽

Normal Women ◽

Fibrinolytic Potential ◽

Increased Activity

SummaryComponents of the fibrinolytic system were studied in samples of plasma from 15 normal, young women and from 11 women taking oral contraceptives containing 30 μg ethinyl oestradiol and 150 μg levo-norgestrel. Fibrinolytic activity of euglobulins precipitated at pH 5.9 was higher than normal in the hormone group, with significant fluctuations related to the cycle. Normal women showed only minor fluctuations. The concentration of C1-inactivator was lower in euglobulins of the hormone group. However, the difference in fibrinolytic activity was retained, when C1-inactivator was inactivated with sodium flufenamate. Fluctuations of the extrinsic (tissue-type) plasminogen activator (t-PA) activity parallelled those of the euglobulin activity.The intrinsic plasminogen activator activity (dextran sulphate precipitated euglobulin) was significantly increased in the hormone group and the cyclic pattern differed from that of the normal group. The increased activity was factor XII-dependent. Plasma prekallikrein did not differ. The factor XII level was increased in the hormone group but this could not explain the increased intrinsic fibrinolytic activity, suggesting an increase in the quantity of an additional factor XII-dependent proactivator.

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On the Fibrinolytic System in Aged Rats, and Its Reactivity to Endotoxin and Cytokines

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648525 ◽

1992 ◽

Vol 67 (06) ◽

pp. 697-701 ◽

Cited By ~ 6

Author(s):

J J Emeis ◽

A Brouwer ◽

R J Barelds ◽

M A Horan ◽

S K Durham ◽

...

Keyword(s):

Plasminogen Activator ◽

Fibrinolytic Activity ◽

Fibrinolytic System ◽

Tissue Type ◽

High Dose ◽

Base Line ◽

Aged Rats ◽

Tissue Type Plasminogen Activator ◽

Young Rats ◽

Type Plasminogen Activator

SummaryAged rats are more susceptible to endotoxin-induced effects, including microthrombosis and platelet aggregation, than are young rats. To investigate whether changes in the fibrinolytic system might be involved, we investigated the fibrinolytic activity in plasma euglobulin fractions and tissues (lung and heart) of young (6-months old) and aged (24-months old) rats under baseline conditions and after challenge with endotoxin. Aged rats had lower plasma levels of tissue-type plasminogen activator (t-PA) and of urokinase-type PA (u-PA) activity. PA inhibitor (PAI) activity was higher in the plasma of aged rats, as was t-PA activity in lung and heart.Rats were treated with either a low dose (1 μg/kg) or a high dose (10 mg/kg) of endotoxin. Both treatments induced a transient phase of increased blood fibrinolytic activity, as evidenced by higher levels of tissue-type plasminogen activator (t-PA) activity and decreased levels of PA inhibitor (PAI) activity. Over time, the fibrinolytic activity decreased, probably due to increased levels of PA inhibitor.Both the early increase in t-PA activity, and the subsequent increase in PAI activity, were more pronounced in the aged rats, as compared with the younger rats, after the high dose of endotoxin. The aged rats also responded to an injection of interleukin-1β or tumor necrosis factor-α with a larger increase of PAI activity than did the younger rats.Together the data suggest that, compared to young rats, aged rats have a decreased base-line plasma fibrinolytic activity, while their fibrinolytic system is more responsive to challenge by endotoxin and cytokines.

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