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

The effects of a low-dose oxytocin infusion on blood pressure during late pregnancy and early puerperium are unclear, and its effects on the renin-aldosterone axis are unknown. The present investigation was performed in 24 pregnant subjects at term and in 14 women within five days after vaginal delivery, 10 and 7 of these subjects serving as controls (5% laevulose being infused without oxytocin). A slight but significant decrease of plasma renin activity was found during oxytocin infusion antepartum as well as postpartum. The decrease of aldosterone concentration in plasma was also significant during late pregnancy, but not during the puerperium. An increase of diastolic blood pressure was only observed antepartum. In summary, however, the changes of blood pressure, renin and aldosterone described in the perinatal period in normotensive subjects were small and without clinical importance.
 ...
PMID:[Effect of oxytocin on renin activity and aldosterone concentration in plasma as well as blood pressure in late pregnancy and early puerperium]. 389 79

The survival of adult rat hepatocytes in monolayer culture was studied in the presence of different hormones (neurotensin, oxytocin, thyrotropin releasing hormone, luteinizing hormone releasing hormone, cholecalciferol, bradykinin, substance P, aldosterone, melanocyte stimulating hormone, 3,3',5-triiodo-1-thyronine, corticosterone, human growth hormone, glucagon, insulin, progesterone, testosterone, estradiol, and dexamethasone phosphate) or growth factors (fetal bovine serum). For this purpose trypan blue exclusion, lactate dehydrogenase, and DNA and protein content were measured at 24 and 72 h of culture. 10(-7) M Dexamethasone, a mixture of eight hormones, 10% fetal bovine serum, and a combination of the latter two supplements caused a more than 64% higher DNA content at 72 h when compared to control cultures. A striking agreement of these results with changes of lactate dehydrogenase leakage was observed, whereas trypan blue exclusion gave erratic results. Considerable changes of cell arrangement apparently specific for each supplement were observed by low magnification microscopy. It is concluded that glucocorticoids and fetal bovine serum have an outstanding effect on cell viability and that DNA or protein content or both are reliable indicators of cell viability in amitotic cultures.
 ...
PMID:Influence of hormones and growth factors on viability, DNA, and protein content of adult hepatocytes in primary culture. 405 11

1. The intracellular (I.C.) concentrations of Na, K and Cl in mammary cells from lactating guinea-pigs have been calculated from the analysis of fresh tissue and the measurement of the extracellular (E.C.) space with [(14)C]sucrose and the milk content with [(14)C]lactose.2. Assuming that alveolar milk has the same concentration as teat milk, the intracellular concentrations were calculated to be K 115, Na 42 and Cl 66 m-equiv. l(-1) intracellular water.3. Intracellular concentrations were also calculated in slices incubated in Krebs-bicarbonate medium plus glucose. There was a large increase in the sucrose (E.C.) space and a rise in total tissue [Na] and [Cl]. On the assumption that the medium had equilibrated with the milk space as well as the E.C. space, the calculated I.C. concentrations of Na (43 m-equiv. l(-1)), and Cl (62) were very similar while [K] was somewhat higher (143 m-equiv. l(-1)I.C. water).4. The calculated I.C. concentrations of all three ions are all higher than in milk but the ratios between them are almost identical.5. Similar figures for the I.C. concentrations of Na, K and Cl have been obtained in the goat, cow and sheep mammary tissue incubated in vitro.6. Moderate changes in the concentrations of Na, K and Cl in the external medium had no effect on cell composition but during incubation without ions [(14)C]sucrose became distributed throughout the total tissue water indicating that sucrose had entered the I.C. compartment.7. Acetazolamide (10(-2)M), aldosterone (1.4 x 10(-6)M) and, in some experiments, lack of glucose lowered I.C. [Cl(-)], but oxytocin, vasopressin and low doses of insulin had no effect.8. The data are difficult to reconcile with the hypothesis of Zaks, Natochin, Sokolova, Tanasiichuk & Tverskoi (1965) that freshly secreted milk has the ionic composition of plasma.9. Comparison of I.C. ion concentrations and the membrane potential between the cells and milk suggests that Na(+) and K(+) are passively distributed across the apical membrane but that Cl(-) must be actively held in the cells. Across the basal membrane the data are consistent with the presence of a Na(+) pump and with Kinura's (1969) detection of a Na:K ATPase on the basal and lateral membranes. In addition another inward-facing Cl(-) pump may exist at this site.
 ...
PMID:Intracellular concentrations of sodium, potassium and chloride in the lactating mammary gland and their relation to the secretory mechanism. 510 48

The total Na+/K+ ATP-ase activity of the thick ascending limb of the loop of Henle may be stimulated by arginine-vasopressin (AVP). Lysine-vasopressin (LVP), oxytocin (OT), and arginine-vasotocin (AVT) produce less than 5% of the enzyme activity induced by the same concentration of AVP. Physiological concentrations of a mixture of other hormones with known activity on the kidney (T3, T4, aldosterone, angiotensin II, and OT) did not significantly increase total Na+/K+ ATP-ase activity. Specific AVP antiserum consistently removed greater than 90% of the stimulatory effect of plasma. The concentration of AVP in plasmas from dehydrated subjects was greater than 10 times that of the same subjects hydrated. Intra-assay coefficient of variation was 35% and 52% from 200 microliters and 20 microliters of plasma respectively. The interassay coefficient of variation was 53% and 55% from plasma pools with high and low AVP content.
 ...
PMID:Specificity of a cytochemical bioassay for arginine-vasopressin and its validation for plasma measurement. 632 21

Testosterone (100 nM to 40 microM) antagonized the effect of aldosterone (10 nM) on Na+ transport in the toad bladder measured in vitro as short-circuit current (SCC). Half-maximal inhibition occurred at an antagonist-agonist molar ratio of 150:1. The antagonist action of testosterone was reversed by addition of more aldosterone. The antagonism was specific in the sense that testosterone (20 microM) did not inhibit the response of the SCC to oxytocin (50 mU/ml). By itself, testosterone (up to 20 microM) had no agonist activity on base-line SCC. Finally, testosterone (500 nM to 20 microM) specifically displaced [3H]aldosterone (5 nm) from its cytoplasmic and nuclear binding sites in bladders incubated in vitro at 25 or 0 degrees C and labeled at steady state. There was a significant linear correlation between the effect of testosterone on the aldosterone-dependent SCC and its effect on [3H]aldosterone binding sites in the cytoplasm and in the nucleus. We conclude that 1) testosterone is a specific competitive antagonist of aldosterone, and 2) [3H]aldosterone nuclear and cytoplasmic binding sites could be mineralocorticoid receptors, mediating the action of aldosterone on Na+ transport.
 ...
PMID:Testosterone: a specific competitive antagonist of aldosterone in the toad bladder. 677 25

The effect of intense muscular work (80% of maximal oxygen uptake) on responses of plasma hormones involved in electrolyte and water balance were measured in 14 male subjects. They were divided into three groups according to their maximal oxygen uptake and the duration of exercise performed until exhaustion: well trained subjects (group I), trained subjects (group II), and untrained subjects (group III). Pulmonary gas exchange, heart rate, rectal and skin temperature, and weight loss were measured as well as hematocrit and plasma and urine sodium and potassium concentrations. Rectal temperature increased significantly in all subjects after exhaustion. The variation of hematocrit was smallest and the weight loss greatest in the well-trained subjects. Plasma aldosterone, renin activity (PRA), vasopressin (AVP), and neurophysin (Np) displayed highly significant increases after exercise in all three groups: PRA was increased 4.5 times (p < 0.01), aldosterone 13 times (p < 0.05), Np 2.6 times (p pe 0.05), and AVP 4.8 times (p < 0.05). Nevertheless, there was no correlation between the changes in PRA and those in plasma aldosterone, nor between aldosterone and plasma sodium or potassium. At the urinary level, the only striking observation was that free water clearance tends to become positive after exercise. Our results provide evidence that this kind of exercise produces a highly significant increase in plasma levels of the hormones involved in electrolyte and water balance. They also indicate that it is among the well-trained subjects that sweat loss is highest though the hematocrit increase is the smallest; this suggests that water is shifted more efficiently from the extravascular compartment.
 ...
PMID:Plasma AVP, neurophysin, renin activity, and aldosterone during submaximal exercise performed until exhaustion in trained and untrained men. 699 37

The subfornical organ (SFO) was suggested to be the site of the central nervous system which mediates the stimulatory effect of angiotensin II (AII) on corticotropin (ACTH) release. To verify this hypothesis, ACTH response to peripherally administered AII was measured in rats with electrolytic lesion of the SFO. Increase in ACTH levels in response to AII (0.5 micrograms/kg or 2.0 micrograms/kg i.v. within 2 min) in conscious cannulated rats was dose-related and it was not affected by SFO lesion. The short infusion of AII (2.0 micrograms/kg) was enough to induce an elevation in plasma oxytocin. Oxytocin response to AII was reduced while that of aldosterone and blood pressure was not modified by SFO lesion. Our data show that an intact SFO is needed for a full response of oxytocin but not of ACTH release to peripherally injected AII.
 ...
PMID:Angiotensin II induces reduced oxytocin but normal corticotropin release in rats with lesions of the subfornical organ. 772 Dec 31

The effects of aldosterone on sodium transport and chloride permeability were investigated by electrophysiology in two structurally distinct epithelial used as models for the distal renal tubule: the A6 cell monolayer as compared with the amphibian skin epithelium (ASE). Short-circuit current (Isc) and transepithelial conductance (Gt) were measured in A6 monolayers incubated overnight with(out) aldosterone. Cell and shunt conductances (Gcell and Gsh) were also determined, as well as the conductive nature of the chloride pathway. These parameters were correlated with sodium and chloride fluxes in A6 cells (JNa and JCl) and compared with the data recorded across ASE (Bufo marinus). The existence of a cAMP-dependent chloride secretory pathway in A6 cells was also investigated upon exposition to arginine vasopressin (AVP) or oxytocin. When A6 monolayers were incubated with aldosterone, Gt significantly increased with respect to control preparations; this increase resulted solely from an increase in Gcell, and was reflected by a 3-fold increase in Isc. There was a significant relationship between Isc and Gcell, as well as between Isc and JNa in both control and aldosterone-stimulated preparations. The A6 clone used was devoid of cAMP-dependent chloride secretory activity and was unresponsive to AVP or oxytocin. Thus, comparison between ASE and A6 preparations revealed two major differences: unlike ASE, (i) aldosterone has no effect on Gsh and (ii) no conductive reabsorptive chloride pathway is operative in A6 monolayers tested. In addition, cobalt had no effect on electrical parameters of A6 monolayers. These observations show that difference in epithelial structure is reflected in terms of electrophysiological response to aldosterone, which suggests that cell heterogeneity could be a prerequisite for observing a conductive reabsorptive chloride pathway in aldosterone-responsive, sodium-transporting epithelia.
 ...
PMID:Aldosterone interaction on sodium transport and chloride permeability: influence of epithelial structure. 775 54

Sheep which were predominantly urinary excretors (U) or faecal excretors (F) of sodium were exposed to a 75% reduction of water intake for 72 h. The experiment was performed on moderate, low or high sodium intakes (0.4, 0.05 or 1.2 mmol kg-1 day-1) to test the hypothesis that dehydration natriuresis was not a cause of sodium depletion but a defence against hypernatraemia. Dehydration caused elevation of plasma sodium concentration, osmolality, antidiuretic hormone (ADH) and oxytocin but, as in other experiments, a fall in haematocrit. The two higher levels of sodium intake were associated with dehydration natriuresis but also a smaller increase in faecal sodium excretion in both U and F sheep. On low sodium intake, however, neither urinary nor faecal sodium excretion increased in either group of sheep although the rise in plasma sodium concentration caused by dehydration was similar. Thus, when there is a risk of sodium depletion, due to low sodium intake, dehydration natriuresis does not occur, consistent with the hypothesis. Active sodium transport inhibitor (ASTI) and atrial natriuretic peptide (ANP) fell rather than rose during dehydration. Since aldosterone is suppressed by the higher levels of sodium intake, none of these hormones is likely to mediate dehydration natriuresis in sheep. F sheep showed more effective renal and faecal water conservation when dehydrated. During water restriction, the urinary potassium excretion of U sheep was significantly reduced, unlike that of F sheep; moreover, the latter maintained an identical plasma potassium concentration between baseline and restriction period, whereas in U sheep it was 0.3 mmol l-1 higher during water restriction. Increased drinking rather than reduced urine output was the basis of rehydration when ad lib. water intake was restored.
 ...
PMID:Responses to reduced water intake, including dehydration natriuresis, in sheep excreting sodium predominantly in urine or in faeces. 778 17

The possibility of an interaction between oxytocin and aldosterone to influence renal Na+ excretion was investigated in Inactin-anaesthetized male Sprague-Dawley rats. Endogenous plasma concentrations of aldosterone were suppressed by either adrenalectomy or bicarbonate infusion. The effects of 2 h intravenous administration of oxytocin (0.04 pmol/min) and/or aldosterone (42 pmol/min) on renal Na+ handling were studied in 0.077 M NaCl-infused adrenalectomized (Adx) rats and groups of intact animals that were infused with 0.077 M NaHCO3. Aldosterone alone significantly (P < 0.01) reduced Na+ excretion from pretreatment peak value of 5.0 +/- 1.0 to 1.5 +/- 0.4 mumol/min in Adx animals (n = 8) and 9.2 +/- 1.2 to 5.2 +/- 1.2 mumol/min in NaHCO3-infused rats (n = 8) by 2 h after the start of administration. However, combined administration of aldosterone and oxytocin was associated with a significantly (P < 0.01) increased Na+ excretion rate from a peak pretreatment value of 6.8 +/- 0.7 mumol/min to a peak value of 11.5 +/- 1.1 mumol/min by 1 h 40 min after the start of treatment in Adx rats (n = 7). In bicarbonate-infused rats (n = 8) Na+ excretion rose within 20 min of the start of treatment from a pretreatment peak of 9.0 +/- 0.8 mumol/min to a peak value of 13.5 +/- 0.8 mumol/min in response to combined hormone administration. In conclusion, we have shown that concomitant administration of aldosterone and oxytocin increased the rate of excretion of Na+ in two different preparations, which supports the idea of an interaction between the steroid and oxytocin to promote Na+ loss.
 ...
PMID:Interaction of aldosterone and oxytocin to influence renal sodium excretion in rats. 781 65


<< Previous 1 2 3 4 5 6 7 Next >>