Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The case reports are presented of two patients who developed water intoxication after high-dose oxytocin infusions. Plasma sodium and urine flow were studied in two further patients given high-dose oxytocin infusions. The findings are related to previously published observations.
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PMID:Water intoxication and oxytocin infusion. 84 73

Rat posterior pituitaries were extracted in acid and total rat neurophysins were isolated. Preparative disc gel electrophoresis separated the total neurophysins into three main peptides of differing electrophoretic mobility. Antisera raised in rabbits recognized a common antigenic site in the three peptides and identical radioimmunoassay standard curves were obtained with each of the isolated rat neurophysins. A homologous rat neurophysin radioimmunoassay was utilized to measure neurophysin in samples of unextracted rat plasma. Basal neurophysin levels, 3.7 +/- 0.2 ng/ml (mean +/- SEM), did not differ in samples collected by decapitation, carotid artery cannulation, or tail vein bleeding. Water-loading caused a significant reduction in neurophysin, 2.8 +/- 0.1 ng/ml, while hypertonic saline and dehydration caused a significant elevation, 10.4 +/- 2.1 and 8.0 +/- 1.4 ng/ml, respectively. A step-wise decrease in blood volume caused a step-wise increase in plasma neurophysin concentrations which returned to baseline with reinfusion of the withdrawn blood. A second hemorrhage caused an even greater release of neurophysin indicating large neurophysin reserve in the pituitary. In periodic tail vein samples over 23 days of pregnancy a rise in plasma neurophysin was found from day 14 continuing to parturition with a peak value of greater than 13 ng/ml by day 21. Two days postpartum the value was 4.6 +/- 0.3 ng/ml. With this homologous assay, the basal levels of plasma neurophysin are lower and the stimulated values higher than with previously reported heterologous assays. Therefore, the relative change with physiologic maneuvers is distinctly increased.
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PMID:Isolation, radioimmunoassay and physiologic secretion of rat neurophysins. 84 27

[8-Lysine]oxytocin was synthesized on a solid support and possessed an oxytocic activity of 100 +/- 6 units mumol on the isolated rat uterus. The epsilon-carbamoyl, epsilon-3-carboxypropionyl and epsilon-3-carboxybutryl derivatives were prepared and had uterotonic activities of 400, 55 and 50 units/mumol respectively. [8-Lysine]oxytocin was coupled unambiguously through the epsilon-amino group to the carboxyl groups of carboxymethylated dextrans or epsilon-3-carboxypropionly-gelatin. The macromolecular oxytocins were water-soluble and retained signigicant oxytocic activity. [8-Lysine]oxytocin should prove a useful ligand for affinity chromatography of oxytocin-binding proteins.
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PMID:Biologically active macromolecular forms of oxytocin. [8-Lysine]oxytocin as a suitable ligand. 88 73

A radioimmunoassay for AVP capable of measuring human plasma AVP is described. Iodination was performed by the chloramine T method and purified by chromatography on Sephadex G-25. Specific activity of 125I-AVP was 1710 +/- 155 Ci/mmol. Antiserum of high affinity (Keq = 2.7 X 10(11) 1/mol) has been raised in rabbits, which shows slight cross-reactivity with LVP and negligible reactivity with oxytocin. The aqueous assay is capable of detecting 0.4 fmol of AVP/tube and it is highly reproducible. A F lorisil extraction technique is described in detail and gives recovery of 70% of synthetic AVP added to plasma over a wide physiological range. The lowest detectable concentration of plasma AVP is 0.3 pmol/l. The method has been validated by studying changes in plasma AVP concentration following overnight dehydration (plasma AVP =3.46 +/- 1.89 (SD) pmol/l), and water loading (plasma AVP = 1.54 +/- 0.59 pmol/l), P less than 0.005, in normal subjects. A highly significant positive correlation has been found between plasma AVP and plasma osmolality (r =+0.75). Plasma AVP concentration has also been determined in patients with DI and the syndrome of inappropriate ADH secretion. No effect was found on the level of plasma AVP in normally hydrated volunteers undergoing postural change but levels rose following strenuous exercise from basal concentrations of 1.57 +/- 0.59 pmol/l to 4.77 +/- 3.43 pmol/l, P less than 0.01.
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PMID:The development of a radioimmunoassay for the measurement of human plasma arginine vasopressin. 89 Oct 2

1. In conscious lactating goats a significant correlation was found between blood-milk potential difference (p.d.) and milk [lactose] such that in goats with a lower milk [lactose], milk was more negative with respect to blood.2. When mannose was substituted for glucose in the substrate mixture of isolated perfused goat mammary glands, milk yield and milk [lactose] fell while milk [Na] and [K] increased; in parallel experiments the blood-milk p.d. changed such that milk became more negative with respect to blood. These changes were reversed following the addition of glucose.3. When milk was made hypertonic by the addition of hyperosmotic sucrose or lactose solutions, water entered milk osmotically and milk became electrically less negative or even positive with respect to blood in goats, cows and guinea-pigs.4. No effect on p.d. was apparent following the addition of isosmotic sucrose to milk in goats.5. When milk was held in the teat of goats by a pneumatic cuff around the base of the teat, no effect on p.d. was apparent when hyperosmotic sucrose was introduced into this teat pouch.6. It is suggested that waterflow-induced potentials (the streaming potential and the transport number effect) can be induced across the mammary epithelium.7. In goats exogenous oxytocin lowered milk [lactose] and blood-milk p.d. became less negative with respect to blood.8. In non-lactating and mastitic glands of goats the blood-milk p.d. was within 0.5-2.5 mV of zero.9. The effects of oxytocin, and the low p.d. in non-lactating and mastitic glands, are compatible with the view that in such circumstances there is a paracellular pathway across the mammary epithelium which partially short-circuits the two sides.10. It is suggested that, with water being drawn osmotically into milk to dilute newly formed lactose, waterflow-induced potentials may be responsible for establishing the normal p.d. across the apical membrane of the secretary cell, thereby keeping milk [K] and [Na] lower than in intracellular fluid.
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PMID:Mechanism of milk secretion: milk composition in relation to potential difference across the mammary epithelium. 90 3

The conformation of the CCSSCC moiety in oxytocin and lysine vasopressin is investigated using laser Raman spectroscopy. The Raman spectra of solutions of these hormones in water and in dimethyl sulfoxide show an intense band at 508 cm-1 which is assigned to the S-S stretching mode. The presence of shoulders on this band between 490 and 525 cm-1 shows that there is an equilibrium among several conformations for the disulfide unit of these hormones in solution. Most of the CS-SC dihedral angles are within 30 degrees of +/-90 degrees, but some of the molecules have CS-SC dihedral angles strained away from this value by more than 30 degrees. The previously published circular dichroism spectra of these hormones are reinterpreted, and it is shown that the circular dichroism spectra indicate the presence of more than one conformation for the disulfide unit, in agreement with the Raman results.
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PMID:A Raman spectroscopic investigation of the disulfide conformation in oxytocin and lysine vasopressin. 91 68

The uptake of the RNA precursor [3H] orotic acid by 18 brain regions of male rats was measured after intracarotid injection and a survival time of 15 s. Ocytocin added to the injected solutions (final concentrations: 1 to 1000 mU/ml) caused a dose-dependent enhancement of tracer uptake by 11 areas. Some of these regions (e.g. hippocampus) are thought to be involved in the behavioral effects of vasopressin and other peptide hormones (Van Wimersma Greidanus et al., 1975 a). Results of experiments in which the net uptake of tritiated water was used as a measure of relative blood flow led us to the conclusion that the blood-brain barrier permeability to [3H] orotic acid rather than the cerebral blood flow is changed by ocytocin. The present results support the assumption that the enhanced precursor supply caused by ocytocin might contribute to the influence of this peptide hormone on memory consolidation.
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PMID:[Effect of oxytocin on regional 3H-orotic acid uptake in rat brain]. 92 28

Vasopressin and oxytocin were measured by radioimmunoassay in rat posterior pituitary and microdissected hypothalamic areas after 3 and 10 days of oral 2 percent sodium chloride in place of drinking water. There was a significant decrease in concentration of both hormones in posterior pituitary and in specific areas of the hypothalamus. Supraoptic, paraventricular, and arcuate hypothalamic nuclei and the retrochiasmatic area had decreased concentration of one or both hormones following hypertonic saline, while hormone concentration in the suprachiasmatic nucleus and median eminence was unaffected.
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PMID:Vasopressin and oxytocin are depleted from rat hypothalamic nuclei after oral hypertonic saline. 93 63

Neurohypophyseal dispersions and fractions enriched for neurosecretosomes and pituicytes were prepared from rats subjected to 6 days of water deprivation and 9-10 days of lactation as stimuli of the hypothalamo-neurohypophyseal system (HNS). After water deprivation the content of the fractions changed in such a way that the neurosecretosomes, and to a lesser extent also the pituicytes, accumulated at a lower density within the gradient used for separation. Stimulation by means of lactation did not show such changes when a comparison was made with dioestrus. Microchemical and histochemical tests for acid phosphatase showed that most of the activity in the controls was present in the neurosecretosomes. A rough calculation, which takes into account the different yields for the dispersion elements, showed a rather equal distribution for acid phosphatase activity between axonal and pituicytic compartments of the intact neurohypophysis. The known acid phosphatase activity response of the neural lobe after HNS stimulation, which was also detectable in the dispersion, resulted histochemically in an increased staining intensity for both neurosecretosomes and pituicytes, but with microassay it was distributed along a gradient similar to oxytocin. It was therefore concluded that this lysosomal enzyme response within the neurophypophysis is preferentially localized in the neurohypophysis is preferentially localized in the neurosecretory axons.
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PMID:Acid phosphatase in rat neurohypophyseal dispersions and its fractions enriched for neurosecretosomes and pituicytes after water deprivation and lactation. 96 51

Observations on water and electrolyte metabolism after hypophysectomy or adrenalectomy, in male and female rats with hereditary hypothalamic diabetes insipidus (Brattleboro strain) are confirmed and extended. The diabetic (homozygous, DI) state relative to the non-diabetic (heterozygous, non-DI) state was characterized by (1) water intake of 55-120% body weight; (2) copious urine hypo-osmotic to plasma; (3) greater excretory rates of total solute, Na, Ca and Mg; (4) similar plasma composition except that in male DI rats, K concentration was less, and in female DI rats osmolarity was higher; (5) glomerular filtration rates (GFR) were similar with close correlations between: food and water intakes, water intake and output, urinary Na and K, Na and Cl, K and Cl, and Ca and Mg; (6) both female DI and non-DI rats had lower urinary Na:K ratios and lower plasma Na concentrations than males; (7) female DI rats excreted relatively larger amounts of K and Cl, and had higher plasma Ca concentrations than other groups. Hypophysectomized DI rats had decreased water intake and urine output, decreased solute excretion, decreased loss of osmotically free water, lower excretory rates of Na, K and Cl, and increased urinary osmolarity and K concentrations. Hypophysectomized non-DI rats had increased urinary excretory rates, decreased solute excretion (by 60-70%), decreased osmotically free water absorption, decreased urinary osmolarity, Na and K concentrations, and increased excretory rates of Ca and Mg. Hypophysectomized DI and non-DI rats had increased plasma osmolarity and Na concentration. Plasma renin activities (PRA) were higher in DI than in non-DI rats with female values lower than those of males; values for both sexes of DI and non-DI rats were reduced after hypophysectomy. Adrenalectomized DI rats had about a 50% reduction in water intake, urine output and free water clearance, increased urinary concentration of electrolytes and total solute by day 4 after operation; their Na balance (dietary:urine) did not change significantly in contrast to adrenalectomized non-DI rats in which a greater percentage of dietary Na appeared in the urine. GFR was similarly reduced in adrenalectomized DI and non-DI rats. Plasma osmolarity increased in adrenalectomized male DI, decreased in female DI and non-DI, and did not change in male non-DI rats. Plasma K concentrations increased after adrenalectomy in all groups, only non-DI rats had a significantly decreased plasma Na concentration. There was no sex difference in pituitary oxytocic activity but it was consistently reduced in DI rats; there was little change after adrenalectomy in male DI and non-DI rats; but there was an increase in DI and non-DI females. Pituitaries of DI rats had no measurable ADH activity (except the inherent activity of oxytocin). Pituitary ADH values for male and female non-DI rats were similar and were unaffected by adrenalectomy.
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PMID:Effects of adrenalectomy and hypophysectomy on water and electrolyte metabolism in male and female rats with inherited hypothalamic diabetes insipidus (Brattleboro strain). 101 Sep 70


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