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 intraamniotic route of prostaglandin (PG) administration is used mainly for terminating pregnancies after the 14th week of gestation. From the clinical point of view, a good method would give a success rate of about 90% within 18-22 hours. With current methods, this is not possible without additional treatment. PGs and its analogs appear to be promising agents. A comparison of hypertonic saline with intraamniotic PGs shows that induced abortion period is significantly shorter with the PG method, although an oxytocin drip added at time of saline administration would produce the same effect. Intraamniotic PG administration is associated with a high frequency of nondangerous side effects (vomiting and diarrhea); however, hypertonic saline is known to have a higher frequency of dangerous side effects. The extraamniotic route of PG administration induces a local stimulating effect on the myometrium, obviating the need for a high systemic concentration of compounds as required by the intravenous route. Such method involves repeated injections of PGs at 2 hour intervals and is successful in approximately 90% of the cases in the 2nd trimester with a mean induction-abortion interval of 20-24 hours. It can also be used in the 13th-14th week of pregnancy. The major disadvantages are the need for repeated instillation and inconvenience of an indwelling catheter with its attendant risk of intrauterine infection. Vaginal PG administration offers the advantage of simplicity and possible utilization on a self-administered basis. It can successfully induce abortion either in the form of a concentrated solution or as lactose tablets impregnated with compounds. The dosage has to be repeated every 2 to 4 hours to maintain a high level of uterine activity. Suppositories have also been used in clinical trials and can be used to induce abortion. Disadvantages are unpredictable individual responses to vaginal administration and high incidence of side effects. Further studies are needed to develop suitable analogs for use in controlling ovulation, fertilization and implantation.
 ...
PMID:Summary of round-table discussion on fertility regulation. 480 97

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

1. When goats were milked each hour after being given a dose of synthetic oxytocin within the range thought to be released by the pituitary, there was a progressive rise in milk yield becoming statistically significant by 5 hr. The effect was reduced if the milk was not removed from the gland each hour.2. Milking transplanted glands each hour without injecting oxytocin also increased milk yield. The yield of the unmilked glands on the same animals was not affected. Massaging the transplanted glands had no effect on the milk yield.3. Oxytocin treatment and, to a lesser extent, frequent milking without oxytocin, altered milk composition. [Na], [Cl] and [non-casein protein] increased; [K] and [lactose] decreased.4. Oxytocin infusions permitted the leakage of [(14)C]lactose from milk to plasma and [(14)C]sucrose from plasma to milk.5. In some goats very small doses of oxytocin caused changes in milk composition and in one such animal these changes were mimicked by the close arterial infusion of bradykinin.6. Reasons are given for believing that the changes in composition are incidental to the main action of oxytocin in expelling milk and could be caused by a small number of leaks between the tight junctions connecting secretory cells.7. The increase in the rate of milk secretion following milk removal is probably of greater physiological significance than the small changes in milk composition and supports Levy's idea of a local negative feed-back via a chemical component of milk.
 ...
PMID:The effects of oxytocin and milk removal on milk secretion in the goat. 510 50

1. The effect of milking goats 1-4 times an hour for 3-12 hr on the yield and composition of milk has been studied in fed and fasted animals at all stages of lactation.2. It was essential to inject oxytocin (50-400 m-u. I.V.) just before each milking to remove all the milk already in the udder and then the yield was similar to that obtained on twice daily milking (105 +/- 2.1 S.E.%). There were no significant differences between goats or between the two glands of one goat, even if one had been denervated by autotransplantation. However, the variation from hour to hour was 1.5 times greater than from day to day.3. The claim of Zaks (1964) and Zaks, Natochin, Sokolova, Tanasichuk & Tverskoy (1965) that milking every 15 min always produces a large rise in milk Na and a fall in K and lactose, which is characteristic of alveolar milk, is not substantiated. In high yielding goats milking gently by hand or with a cannula caused a small change in K only, but vigorous hand milking exacerbated this fall and also caused a fall in lactose and a rise in Na and Cl. Still larger changes were produced by using excessively large doses of oxytocin (2500 m-u.) when there was also a rise in citrate and total nitrogen. Hourly milking in goats fasted for 24 hr had the same effect.4. In fasted goats the milk yield fell to 90% within 8 hr and to 56 +/- 2.1% of the previous level by 24 hr. It remained at this level for a further 10-12 hr on twice daily or on hourly milking. The yields of autotransplanted glands usually fell slightly but significantly more than that of the glands in situ. In most goats mammary blood flow was halved but in all animals there were large falls in mammary uptake of glucose, acetate and amino acids and greatly increased uptake of free fatty acids. There were significant differences between fasted goats on hourly milking.5. It is concluded that, in spite of changes in milk composition, milking hourly can be a useful technique for studying milk secretion. The striking effects of a short fast in a lactating animal are emphasized.
 ...
PMID:The effect of very frequent milking and of oxytocin on the yield and composition of milk in fed and fasted goats. 606 46

1. Experiments have been carried out in lactating goats milked hourly to assess the value of this technique in studies of milk secretion.2. On refeeding 24 hr-fasted goats there was an increase in arterial concentration and mammary uptake of volatile fatty acids within an hour, but little increase in hourly milk and lactose yield until the mammary uptake of glucose had also increased (after 2-3 hr).3. Intravascular infusions of acetate had no effect on milk secretion in 24 hr-fasted goats but glucose infusions increased milk yield by 62 +/- 5% and lactose yield by 87 +/- 12% within 3 hr, with no effect on fat secretion. The addition of acetate or acetate plus amino acids had no more effect than glucose alone.4. The yield of milk and lactose could be reduced within an hour by insulin (2 u./kg I.V.) and this was prevented or reversed by injecting glucose. In one goat, where in spite of a fall in blood sugar, mammary arteriovenous difference and blood flow did not fall, there was little or no fall in milk yield.5. In fasted or insulin treated goats an increase in milk and lactose secretion could be obtained within an hour by infusing glucose into the artery of one gland autotransplanted to the neck, which responded before the control gland in situ, thus showing that the effect of glucose is directly on the mammary tissue.6. In two normally fed goats with a low blood sugar, glucose infusions increased the milk or lactose yield by 30% within 3 hr.7. It is concluded that frequent milking, using minimal doses of oxytocin, is a valid method of studying factors controlling milk secretion and that, in the lactating goat, the availability of glucose to the mammary gland can be a limiting factor for maximum milk secretion.
 ...
PMID:The effect of infusions of glucose, acetate and amino acids on hourly milk yield in fed, fasted and insulin-treated goats. 606 16

Lactational performance, milk composition, mammary calcium pools and serum calcium were examined in vitamin D-deficient lactating mice to determine whether the mammary gland is a target organ for vitamin D. CD1 mice were fed vitamin D-deficient or control diets containing 1.2% calcium and 0.5% phosphorus 8-12 weeks prior to breeding. Plasma calcium levels were within normal limits in all mice. Vitamin D deficiency was verified by lack of detectable serum 25-hydroxycholecalciferol. Deficient mice had fewer pups per litter than controls (7.1 +/- 0.5 vs. 8.4 +/- 0.3; P less than 0.05). Pups from vitamin D-deficient and repleted mothers grew at the same rate. Mammary tissue intracellular and extracellular calcium pools, measured by an efflux technique, did not differ in the two groups. Milk samples were collected by suction after injection of 0.1 IU of oxytocin i.p. or anaerobically by a surgical technique. Although protein, Na, K, ionized calcium and pH did not differ, milk from vitamin D-deficient mice had lower lactose (114.6 vs. 135.9 mM; P less than 0.02) and slightly lower calcium (66.8 vs. 75.4 mM; P less than 0.1) concentrations than controls. The data do not demonstrate any direct effects of vitamin D on mammary gland calcium metabolism.
 ...
PMID:Effect of vitamin D deficiency on mouse mammary gland and milk. 669 84

The concentration of lactose in plasma was determined in different sows at all phases of their reproductive cycle and related to the compositional changes in mammary secretion during lactogenesis, established lactation and weaning. Lactose was present in low concentrations (3-4 microM) in the blood of virgin sows and pregnant sows up to 107 days of gestation. From day 4 pre-partum to day 1 pre-partum circulating lactose rose gradually to 34.5 +/- 7.7 microM (mean +/- S.E. of mean). Maximal concentrations of 262 +/- 168.4 microM were reached 6 h after parturition. The concentration of lactose in plasma was correlated with the amount of lactose in mammary secretion (r = 0.88, P less than 0.01) at the beginning of farrowing. During established lactation the concentrations of lactose, Na and K in milk, and of lactose in plasma (72-86 microM), were constant. The concentration of lactose in plasma did not vary significantly during periods of suckling, or after stimulation of milk ejection by oxytocin. However, the amount of lactose in plasma rose significantly (P less than 0.02) after the administration of oxytocin if milk ejection was not accompanied by suckling. The mean plasma concentration of lactose began to rise 36 h after weaning to a peak value of 241.8 +/- 53.6 microM at 48 h; thereafter it declined to 10.2 +/- 2.0 microM by 6 days. This study has shown that lactose concentrations in the plasma vary according to the secretory activity of the mammary gland. Its plasma concentration provides an earlier temporal measure of lactogenesis in individual sows than is obtained either from observation or analysis of mammary secretion.
 ...
PMID:Lactose in plasma during lactogenesis, established lactation and weaning in sows. 670 63

Milk intake (sucking-test weight) by 55 Dorset lambs and milk production (oxytocin-hand milking) by 41 Dorset ewes were measured at 2-wk intervals during the first 8 wk of lactation. Each method indicated that milk yield by ewes was greater at 2 and 4 wk of lactation than at 6 and 8 wk. Daily milk intake by a set of twins (suckling-test weight) was similar to 24-h milk production of their dam (oxytocin-hand milking) when lambs were 2, 4, 6, and 8 wk of age. At 2, 4, and 6 wk postpartum, milk production by ewes nursing single lambs was 200 to 400 g greater than milk intake by lambs due to a larger residual milk. Stage of lactation had a significant effect on protein and fat content of milk but not on lactose. Sex of offspring had no effect on milk yield or protein, fat, and lactose content of milk. Lactose was one percentage unit greater in milk of ewes nursing single lambs; however, the amount of lactose secreted daily was similar for ewes nursing single or twin lambs. Twenty-four-hour milk production by the ewe as determined by the oxytocin-hand milking method was correlated with lamb growth (.67 to .86), with milk intake, as determined by the suckling-test weight method, the next most important variable. Milk composition contributed little toward modeling lamb growth.
 ...
PMID:Milk yield by Dorset ewes as affected by sibling status, sex and age of lamb, and measurement. 672 24

1. Injection of citrate or EGTA solutions into the lumen of the mammary gland of goats in quantities sufficient to reduce ionized calcium to less than one-tenth of normal, led to increases in milk concentrations of Na and Cl and decreases in K and lactose. 2. Subsequent milk yields were decreased in glands treated with citrate but not in those treated with EGTA. 3. Blood-milk potential difference decreased (i.e. towards zero) in glands in which citrate was present. 4. In goats milked hourly with the aid of oxytocin, milk Na and Cl concentrations increased while K and lactose decreased; there was no apparent decrease in Ca2+ concentration. 5. It is suggested that ionized calcium in milk is essential to preserve the integrity of the mammary epithelium during lactation.
 ...
PMID:Ionized calcium in milk and the integrity of the mammary epithelium in the goat. 679 44

Subcutaneous injections of 30 mg atropine into lactating cows induced a 20--40% decrease of free amino acid (AA) levels in arterial plasma. Minimum levels were observed after 30--50 min. The decline persisted for more than 6 h. The greatest fall in concentration was noted for tyrosine, methionine, lysine, arginine, phenylalanine and threonine. Arterial glucose levels remained unaffected. The effect of atropine on milk secretion was studied in 2 cows which were milked every hour with the aid of oxytocin. Maximal effects were observed after 3--4 h. They included reduction in concentration of casein and alpha-lactalbumin (alpha-la) and a decline in production of milk (20%), casein (35%), alpha-la (45%) and lactose (18%). Uptake by the lactating udder over a period of about 1 h after injection of atropine was studied in 2 cows. Mammary blood flow and glucose uptake remained unaffected. There was a positive correlation between arteriovenous differences of essential AA and arterial plasma concentrations. The uptake of essential AA decreased by approximately 50%. There was no evidence that atropine has a direct inhibiting effect on the udder. It is suggested that the decrease of alpha-la synthesis might induce an inhibition of lactose synthesis and milk production.
 ...
PMID:Effect of atropine on plasma amino acid levels and milk secretion of cows. 719 9


<< Previous 1 2 3 4 5 Next >>