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

The haemodynamic effects of oxytocin (Syntocinon) and methyl ergometrin (Methergin) were studied in 9 healthy females in the first trimester of pregnancy. The patients were anaesthetized with sodium thiomebumal, pethidine and pancuronium bromide and ventilated on a Manley respirator. 10 i.u. oxytocin given as an i.v. bolus brought about a fall in femoral arterial pressure of 40%, systemic resistance 59% and pulmonary resistance 44% 30 sec after injection. However, the heart rate increased 31% and stroke volume 17%, so that the cardiac output increased by 54%. The pulmonary arterial pressure and wedge pressure were increased by 33% and 35%, respectively 150 sec after injection. No changes were seen in the haemodynamic parameters during infusion of 80 mU oxytocin for 10 min. 0.2 mg Methergin brought about an increase in the femoral arterial pressure of 11%, pulmonary arterial pressure 27% and wedge pressure 31%, with no changes in the other measured parameters. The use of oxytocic drugs in patients with compromised circulation is discussed.
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PMID:Haemodynamic effects of oxytocin (syntocinon) and methyl ergometrine (methergin) on the systemic and pulmonary circulations of pregnant anaesthetized women. 63 63

We have studied the effect of nonsteroidal antiestrogens on rat uterine contractions induced by oxytocin (8 nmol/l), methacholine (10 mumol/l), prostaglandin F2 alpha (1 mumol/l), KCl (60 mmol/l) and CaCl2 (6 mmol/l). In a concentration-dependent way, the antiestrogens tamoxifen, clomiphene, nafoxidine and ethamoxytriphetol inhibited the amplitude and frequency of the oxytocin-induced contractions and the contraction produced by CaCl2. At a concentration of 30 mumol/l the four drugs inhibited the contractions induced by methacholine and prostaglandin F2 alpha. They also relaxed the tonic contraction to KCl in a concentration-dependent way. This action was partially counteracted by CaCl2 (0.1-10 mmol/l). Bay k 8644 (0.3 nmol/l to 3 mumol/l) only partially reversed the inhibition by ethamoxytriphetol (0.1 mmol/l) of CaCl2 (6 mmol/l)-induced contractions. The steroidal antiestrogen, ICI 164,384, which lacks agonist activity, had an inhibitory effect (44 +/- 4%, n = 7) on KCl-induced contractions only at a concentration of 0.1 mmol/l. However, the quaternary analogue of tamoxifen (tamoxifen ethyl bromide) produced 86 +/- 3% relaxation of the KCl-induced contracture (IC50 1.52 +/- 0.1 mumol/l, n = 10) and this effect was counteracted by addition of CaCl2. Taken together the results indicate that the inhibitory effects of nonsteroidal antiestrogens on rat uterine contractions could be mediated by an action to block Ca2+ entry through an agonist action on extracellular estrogen receptors.
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PMID:Effects of nonsteroidal antiestrogens in the in vitro rat uterus. 148 55

The Authors have correlated neonatal jaundice with the administration of oxytocin and prifinium bromide to the mother either alone or in association during labour. The percentage of neonatal jaundice in women treated with ritodrine hydrochloride during the second and third trimester of pregnancy was also calculated. A total of 1.101 deliveries were taken into consideration between January 1984 and June 1986. Thirty-three patients were treated with oxytocin alone; 444 patients with oxytocin and prifinium bromide; 81 patients with ritodrine hydrochloride during the second and third trimesters of pregnancy, and 192 patients were untreated. This study indicates that all drugs may contribute to producing neonatal jaundice, as shown in the graphs, and drugs during labour should be used with extreme caution and be limited in quantity and period.
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PMID:[Effect of some drugs on physiological icterus in the newborn]. 168 95

Hypothalamic paraventricular and supraoptic neurons were recorded intracellularly in coronal slices and injected with Lucifer yellow, ethidium bromide or biocytin. Electrical properties, morphological staining and neurophysin immunohistochemistry were compared among the 3 markers. Lucifer yellow electrodes had a high resistance and frequently blocked during experiments. Neurons recorded with Lucifer yellow electrodes had low input resistances and low-amplitude, broad spikes. Lucifer yellow labeling in whole mount was highly fluorescent, revealing distal dendrites and axons. Of cells injected with Lucifer yellow, 64% were recovered but were faint after immunohistochemical processing. Recordings with ethidium bromide electrodes were similar to controls, although electrode blockage sometimes occurred. Only somata and proximal dendrites of ethidium bromide-filled neurons were visible in whole-mount. Forty percent of cells injected with ethidium bromide were recovered after immunohistochemical processing; these were invariably faint. Recordings with biocytin-filled electrodes were similar to control recordings. Biocytin-filled, HRP-labeled cells showed distal dendrites and often dendritic spines and axons in 50-75-microns sections. Seventy percent of biocytin-injected cells labeled with fluorescent markers were recovered and remained strongly labeled after immunohistochemical processing. Biocytin had the best electrical and staining properties for combined electrophysiological and anatomical studies.
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PMID:Comparison of three intracellular markers for combined electrophysiological, morphological and immunohistochemical analyses. 172 76

Two intact and 2 ovariectomized mares aged 3-16 years had bipolar electrodes implanted in the myometrium to measure electromyographic (emg) activity during normal and exogenously simulated (with oestrogen and progesterone) cyclical activity (anoestrus, transition, oestrus and dioestrus). Oxytocin, cloprostenol, propantheline bromide and clenbuterol were administered during each cycle stage. In 1 mare, emg activity was recorded during natural breeding (4 times) and through the first 20 days of pregnancy. Simultaneous intrauterine pressure recordings (IUP) using an open tipped catheter system were taken occasionally. For mares in oestrus, we recorded short bursts of high amplitude emg activity separated by quiet periods, a pattern that is indicative of uterine contractions. During dioestrus the duration of emg activity increased, but amplitude decreased and interspersed quiet periods were less well defined, indicative of uterine tonus. The emg patterns seen in anoestrus and transition were intermediate. At breeding there was a short-lived increase in emg activity, unlikely to be caused by endogenous hormone release. During early pregnancy the emg characteristics varied depending on whether the fertilized ovum was in the oviduct, migratory or fixed, with emg activity increasing to 100% after Day 16 when uterine tone is maximal. Oxytocin and cloprostenol caused prolonged emg activity followed initially by a short burst pattern that was most pronounced in oestrus and least in dioestrus and suggests uterine motility is stimulated to a greater extent during oestrus. Propantheline decreased emg activity, whereas cloprostenol caused minimal changes. IUP increased with uterine stimulants and decreased with uterine relaxants, but showed little variation between cyclic states. There was little correlation, statistically or visually, between IUP and emg activity during the oestrous cycle with or without drug treatment. Because emg analysis gave consistent results and demonstrated significant differences between oestrus and dioestrus that neither agreed nor correlated with IUP, the validity of the IUP recording technique used in this study (as well as those used in general for the mare) is questioned. It is suggested that extrauterine factors such as intestinal motility and intra-abdominal pressure changes could influence IUP responses.
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PMID:Some physiological and pharmacological factors affecting uterine motility as measured by electromyography in the mare. 179 79

The effect of tetanus toxin on neuropeptide hormone release from isolated nerve endings of the neural lobe of rat pituitaries (neurosecretosomes) was measured in a perfusion system. Tetanus toxin inhibited depolarization-evoked release of oxytocin and vasopressin in a time- and dose-dependent manner. At 1 microgram/ml, tetanus toxin blocked stimulated release by 85%. Tetanus toxin that was preincubated with a neutralizing monoclonal antibody or heated to 100 degrees C had no effect on hormone release. The ionophores A23187 and ionomycin were potent stimulators of hormone release in control nerve endings, but were not able to overcome the effect of tetanus toxin in intoxicated nerve endings. 8-Bromo-cyclic GMP, which has been reported to reverse the action of tetanus toxin in PC12 cells, had no effect on the action of tetanus toxin in neurosecretosomes. Neurosecretosomes are the first system in which tetanus toxin has been shown to block release from peptidergic nerve terminals. They appear to be a valuable in vitro system for studying the biochemical mechanism of tetanus toxin action.
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PMID:Effect of tetanus toxin on oxytocin and vasopressin release from nerve endings of the neurohypophysis. 217 68

1. Isolated nerve endings from rat neurohypophyses were permeabilized with digitonin in order to gain access to the cytoplasm. Release of vasopressin (AVP), oxytocin and the neurophysins was studied under different experimental conditions. 2. Hormone release, which occurred by exocytosis, was Ca2+ dependent. Half-maximal release was observed at ca. 1.7 microM-Ca2+ in contrast to ca. 300 microM for K+-induced hormone secretion from non-permeabilized neurosecretosomes. 3. Release also occurred when the neurosecretosomes were challenged with Ca2+ 20 min after digitonin treatment. This suggests that the isolated nerve endings remain permeable after treatment with digitonin. 4. Although hormone release was potentiated in the presence of ATP, and to a lesser extent with guanosine triphosphate (GTP), secretion occurred in the absence of nucleotides. 5. Replacement of K+ as the major cation by Na+ did not modify the secretory response to a Ca2+ challenge. Release, although reduced, still occurred when KCl was replaced by sucrose. 6. Compared to glutamate, Cl-, Br- and I- did not modify the Ca2+-independent release. This release was increased in the presence of SCN-. The order of effectiveness of the anions studied in inhibiting the Ca2+-dependent release was glutamate less than Br- = Cl- = I- less than SCN-. 7. Increasing the osmolarity of the perfusate inhibited the Ca2+-dependent release of AVP and oxytocin. 8. Vincristine, which binds to microtubules, had no effect on the secretory process. 9. Ca2+ dependent AVP release was partially inhibited by the calmodulin antagonist trifluoroperazine. 10. Hormone release was potentiated by the protein kinase C activator, 4-beta-phorbol 12-myristate acetate (TPA). 11. Whereas 0.2 microM-Ca2+ induced a barely significant increase in AVP release, inositol 1,4,5-triphosphate, in the continued presence of 0.2 microM-Ca2+, produced a large secretory response. 12. 4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid (SITS), an inhibitor of Cl- permeability, reduced the Ca2+-dependent AVP release. 13. Carbonyl cyanide m-chlorophenylhydrazone (CCCP), which reduces the transmembrane potential of isolated neurohypophysial granules, inhibited the Ca2+-dependent hormone secretion. 14. Maximal hormone release occurred at pH 6.6. 15. It is concluded that the permeabilized neurosecretosomes represent an excellent model for studying the minimal requirements for neurosecretion.
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PMID:Requirements for hormone release from permeabilized nerve endings isolated from the rat neurohypophysis. 245 Oct

The bovine oxytocin precursor was expressed in Escherichia coli as a fusion protein by cloning the hormone encoding cDNA in frame behind the replicase gene of the RNA phage MS2. By step-wise extraction with different urea concentrations, the fusion protein was enriched in the 7 M urea fraction and further purified by Sephacryl S-300 chromatography. The oxytocin precursor was cleaved off the fusion protein by cyanogen bromide treatment, chromatographed on FPLC columns and identified by Western blot analysis, using antibodies raised against neurophysin.
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PMID:Expression of the bovine hypothalamic hormone oxytocin precursor in Escherichia coli. 313 40

Vasotocin-associated neurophysin (MSEL-neurophysin) from the frog Rana esculenta has been isolated and sequenced through tryptic and staphylococcal proteinase peptides and cyanogen bromide fragments. This protein appears homologous to the mammalian vasopressin-associated neurophysin with a C-terminal glycopeptide extension homologous to the mammalian copeptin. In contrast to the two-step processing of mammalian vasopressin/MSEL-neurophysin/copeptin precursor, a single cleavage is therefore involved in the processing of the amphibian vasotocin/neurophysin precursor. It appears that the physiological release of the vasopressin-like hormone from the N-terminal end of the protein precursor is not dependent upon a previous trimming of the C-terminal copeptin-like moiety.
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PMID:One-step processing of the amphibian vasotocin precursor: structure of a frog (Rana esculenta) "big" neurophysin. 350 Dec 88

Synthetic oxytocin (OT) conjugated to bovine thyroglobulin by the carbodiimide reaction was injected into rabbits to raise a high titre, specific OT antiserum which was then coupled to microcrystalline cellulose activated by cyanogen bromide. High affinity of the coupled antiserum was defined by Scatchard analysis, Keq = 7.1 X 10(11)1/mol. Cross-reactivity studies revealed little binding of antiserum to analogues of OT. Iodination was performed by the Chloramine T method, giving specific activity of 125I-OT, range 1.1 - 1.7 X 10(3) Ci/mmol. After incubation for 40 hours under disequilibrium conditions, specific and non-specific bindings were 10.6 +/- 2.7% and 0.2 +/- 0.1% (n=15), respectively. Displacement of 50% 125I-OT occurred with 2.9 pg OT/tube. Coefficients of variation of standard OT concentrations (0.03 - 16 pg/tube) were less than 5%. Limit of detection was 2 pg OT/ml plasma. Recovery of synthetic OT added to non-pregnant plasma was 81.8% (n=34) at 20 pg/ml and 97.4% (n=32) at 100 pg/ml. Two patients, 17 and 18 weeks post-partum, had increases in plasma OT from less than 2 pg/ml to 18.3 and 16.0 pg/ml after 6 and 4 minutes breast feeding infants, respectively. We conclude that this solid phase OT radioimmunoassay is quick, relatively sensitive and reliable, and does not require prior extraction of plasma samples.
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PMID:Solid phase radioimmunoassay for direct measurement of human plasma oxytocin. 390 Jan 38


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