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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of the neuropeptide oxytocin, administered i. m., on the state of fibrinolysis and the kallikrein-kinin system was studied throughout an experiment on 88 Wistar albino nonpregnant female rats. Oxytocin was shown to cause fibrinolytic activation as a result of the elevated activity of the plasmin enzyme, plasminogen activators and the suppressed activity of antiplasmins. At the same time oxytocin stimulated the activity of the kallikrein-kinin system as was seen from the reduced level of serum kallikreinogen and the increased level of kallikrein.
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PMID:[Effect of oxytocin on fibrinolysis and the status of the kallikrein-kinin system]. 274 Mar 21

Because timing of sampling is crucial in an investigation of the effects of labor and delivery on fibrinolysis we conducted a study of fibrinolytic markers in plasma of 10 healthy multiparous women in whom labor was induced, which allowed standardization of sampling times in relation to the course of labor and delivery. Blood samples were taken 5 min before the start of oxytocin infusion, at full cervical dilatation, and within 5 min after delivery of the placenta. A sample of mixed free flowing cord blood was obtained after delivery with the placenta in situ. Variables determined were tissue-type plasminogen-activator (t-PA) and the plasminogen activator inhibitors type 1 (PAI-1) and type 2 (PAI-2). The only significant change between the beginning of the induction of labor and the end of the first stage of labor was a rise in t-PA antigen (P = 0.01). All variables, except PAI-2 antigen, changed significantly after delivery of the placenta: t-PA antigen and activity showed a rise (P < 0.05), accompanied by a fall in PAI-1 antigen and activity (P < 0.01). T-PA activity in cord plasma was higher (P < 0.01) in comparison with maternal plasma concentrations at the end of the first stage of labor, t-PA antigen levels were similar, and PAI-1 antigen and activity and PAI-2 antigen were lower in cord plasma (P < 0.001). Our study shows that activation of the maternal fibrinolytic system can already be detected during labor, with a marked further increase in fibrinolytic potential after placental separation.
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PMID:Effects of labor and delivery on fibrinolysis. 795 59

Current hypotheses suggest that the degradation of cervical collagen and elastin leads to cervical effacement and dilation during labor. The collagenolytic activity is thought to be initiated through the conversion of latent (pro)collagenase to active collagenase by the plasmin formed from plasminogen or by other proteases similarly formed from their inactive zymogens. We presently demonstrate that meperidine stimulates the activity of several enzymes in the proteolytic cascade leading toward proteolysis of connective tissue proteins. Meperidine in its therapeutic concentration range produces a 26% stimulation of urokinase activity on substrate S-2444, a 39% stimulation of plasmin activity on substrate S-2551, and a 33% stimulation of collagenase activity on 14C-labeled globin substrate. These direct effects on the enzyme activities are noted in vitro with the purified enzymes and were confirmed with several small molecular weight chromogenic substrates and with 14C-globin protein substrate. Oxytocin at levels found during active labor fails to stimulate the in vitro activity of purified urokinase, plasmin, collagenase, trypsin, or tissue-type plasminogen activator. The effect of meperidine on the proteolytic enzymes suggests that its ability to promote cervical effacement and distention during labor may be at least partially due to a meperidine-induced stimulation of cervical proteases.
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PMID:Direct stimulation of urokinase, plasmin, and collagenase by meperidine: a possible mechanism for the ability of meperidine to enhance cervical effacement and dilation. 847 75

The increase in blood clotting factor VIII (antihaemophilic factor, F-VIII) and fibrinolytic activity induced by the administration of neurohypophyseal hormone analogues, was assayed in sheep. Peptides with high selectivity for vasopressin V1, V2 or myometrial oxytocin receptors in the dose range of 0.1-10 micrograms/kg body weight were investigated. The main conclusions are as follows. The time-course of the F-VIII plasma levels following the administration of the peptides was biphasic, with one surge at about 20 min, a rebound phase, and another increase with the maximum at 60-90 min. The time-course of the fibrinolytic response, expressed as biological activity of plasminogen activator in the plasma euglobulin fraction, displayed a single maximum within 60 min. The baseline responses were reached within 90-120 min. Responses were expressed as integrals of the time-concentration curves in a predetermined time range (90-120 min). F-VIII and plasminogen activator enhancing effects seemed to be tightly linked to the specific vasopressin V2 receptor activities. [Val4,D-Arg8]Vasopressin displayed higher plasminogen activator activities than the standard substance, deamino[D-Arg8]vasopressin. The vasotocin analogue [Phe2,Orn8]oxytocin, a specific vasopressin V1 receptor agonist, also displayed high antihaemophilic and fibrinolytic potencies, expressed in terms of ED50 values, but did not reach the same maximal response as vasopressin V2 receptor agonists. Oxytocin and its highly selective uterotonic analogue, [Thr4,Gly7]oxytocin, displayed low antihaemophilic, and virtually no plasminogen activating potencies. Surprisingly, vasopressin V2 and V1V2 receptor antagonists studied in our experiments showed both enhanced F-VIII and fibrinolytic responses. Dose-response curves frequently displayed a decrease of the F-VIII, and sometimes also decreased fibrinolytic responses, at higher peptide doses. Strong decreases of the packed cell volume (haematocrit) and somewhat lower decreases of the total plasma protein concentration were observed shortly after administration of the peptides.
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PMID:Effects of neurohypophyseal hormone analogues on blood clotting factor VIII and fibrinolytic activity in sheep. 912 40

This article documents and quantitatively assesses the capacity of estrogen, phytoestrogens, and antiestrogens to affect biphasic dose-response relationships in animal/human models and across a broad range of cell types, affecting multiple endpoints. The range of endpoints displaying such biphasic dose responses includes plasminogen activation, oxytocin secretion, angiogenesis, cell proliferation, bone growth, monocyte chemotaxis, secretion of various cytokines, and other effects. The quantitative features of the dose response relationships revealed that the magnitude of the stimulatory responses was typically less than twofold, whereas the stimulatory responses were markedly variable ranging from about 5- to 10(6)-fold. Mechanistic explanations of the biphasic responses are addressed.
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PMID:Estrogen and related compounds: biphasic dose responses. 1150 77

The coagulation system of the foetus is markedly different from that of adults. To assess the influence of maternal age, mode of delivery and intrapartum events, and foetal gender and weight on the foetal coagulation system. Cord blood was collected from 154 healthy pregnant women, with gestational age 37 - 42 weeks at birth. Mann-Whitney test was used for analysis of binary data and continuous variables were analysed using Pearson's correlation coefficient. Mean cord blood levels of FVIII:C, VWF:Ag, VWF:CB, FIX, FXI, FXII and plasminogen were significantly higher in babies delivered after labour, compared to those delivered after an elective caesarean. Mean cord blood levels of FII (P = 0.003), FV (P = 0.009), FVII (P = 0.0004) and FX (P = 0.0009) were significantly lower in the babies with meconium stained liquor in labour, compared with those with clear liquor. Augmentation with oxytocin, instrumental delivery, did not affect any of the factor levels and duration of labour did not have an effect on the level of coagulation proteins in cord blood. This study provides valuable information about effect of labour on the coagulation system of the foetus. It is concluded that, in cord blood, the results of coagulation parameters in the newborn baby should be considered in light of mode of delivery and events of labour.
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PMID:The effect of labour on the coagulation system in the term neonate. 2356 Jun 3