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

More than 90 percent of the cells isolated from the mammary gland of lactating rats with 0.1 percent collagenase were viable by dye exclusion. Myoepithelial cells comprised about one-third of the mammary cells and appeared to be morphologically intact in electron micrographs. [(3)H]Oxytocin-binding activity was localized in an enriched myoepitheial cell fraction obtained by density gradient centrifugation of the isolated cells. The amount of [(3)H] oxytocin bound at 20 degree C and pH 7.6 was proportional to the concentration of oxytocin and the number of cells, reaching a steady state by 40 min. About 0.45 fmol of oxytocin were bound per 10(6) cells. There was a single class of independent binding sites with an apparent K(d), estimated from equilibrium conditions, of 5 nM. This value agrees within experimental error with the value calculated from the ratio of reverse to forward rate constants (5.8 x 10(-4)s(-1) and 2.2 x 10(5) M(-1)s(-1), respectively), consistent with a single-step model for the interaction of oxytocin with binding sites on the cells. Erythrocytes bound only 3.5 percent of the amount of oxytocin bound by an equal number of mammary cells. Oxytocin analogues competed with [(3)H]oxytocin for binding sites in the following order: [deamino]oxytocin > [4-threonine]oxytocin > oxytocin > [O- methyltyrosine]oxytocin > [8-lysine]vasopressin; [lysine]-bradykinin and [4-proline]oxytocin were not inhibitory in the dose ranges tested. These results demonstrate that isolated mammary cells possess oxytocin receptors with properties comparable to those found in broken mammary cell preparations.
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PMID:Binding of [3H]oxytocin to cells isolated from the mammary gland of the lactating rat. 19 65

The reaction of secretory epithelium and myoepithelial cells in the alveoli to hand milking and i.v. injection of oxytocin and catecholamines was studied in lactating goats. The reaction of secretory cells was assessed by changes in the transepithelial (blood-milk) potential difference (PD), and the contractile reaction of myoepithelial cells by the growth of intramammary pressure (IP). The initial value of PD was 24.6 +/- 0.6 mV, that of IP 3.32 +/- 0.08 kPa (24.9 +/- 0.6 mmHg). Milking and oxytocin administration caused a rise in PD and an increase in IP. After noradrenaline and adrenaline injections two-phase PD changes and a short-term rise in IP were recorded. Isoproterenol, a beta-agonist, caused a rise in PD but did not affect IP. Phenylephrine, an alpha-agonist, caused two-phase and one-phase changes in PD. Simultaneously, a rise in IP was recorded. The results show that the reaction of the mammary gland to the substances administered is complex. Myoepithelial and secretory cells respond differently to short-term rises in the level of mediators and hormones in the blood.
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PMID:Transepithelial potential difference in the goat mammary gland and its change during hand milking, and administration of oxytocin and catecholamines. 145 32

The objective of this study was to isolate, purify, culture, and characterize myoepithelial cells from bovine mammary glands. Myoepithelial cells were separated from other mammary and blood cells after collagenase digestion and centrifugation using metrizoate-ficoll gradients. Myoepithelial cells were identified by their characteristic morphology and cloned using selective detachment. They contained many densely packed myofilaments, very few cytoplasmic organelles, elongated surface projections, and a dense, irregularly shaped nuclei. Some cells were as large as 1.2 mm in culture. Myoepithelial cells contained an extensive network of cytoskeletal proteins, including alpha-smooth muscle actin, alpha-actinin, and vimentin. When cultured, they tended to repel one another and never grew as closely associated cells. The myoepithelial nature of these cells was verified by showing that they contracted in response to oxytocin, bound oxytocin, and did not produce casein. Myoepithelial cells from fetal and lactating glands grew very well in culture. Active division of myoepithelial cells could be maintained for at least 3 mo, and cells could be serially subcultured at least seven times. The successful isolation and culture of bovine mammary myoepithelial cells make utilization of these cells possible in order to study their role in mammary growth and differentiation and milk ejection.
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PMID:Bovine mammary myoepithelial cells. 1. Isolation, culture, and characterization. 147 4

Myoepithelial and secretory cells from the mammary gland of the lactating rat have been isolated, purified, and characterized. Mammary tissue was dissociated with collagenase into basket-like networks of myoepithelial cells and single secretory cells. Because of their larger size, the myoepithelial cell networks could be separated from other mammary and blood cells by differential centrifugation. Isolated secretory cells were purified by isopycnic centrifugation in 25% bovine serum albumin. The purified myoepithelial and secretory cells were viable, as shown by the incorporation of 32P into distinct macromolecules that were separable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both myoepithelial and secretory cells retained their characteristic morphology after isolation and purification, as shown by light, transmission, and scanning electron microscopies. The isolated myoepithelial cells were unique and, thus, distinguishable from other mammary cells in a number of respects; they 1) contracted in response to the addition of oxytocin, 2) bound [3H]oxytocin specifically, 3) accounted for the content of alkaline phosphatase and [Na+ + K+]ATPase in mammary tissue, and 4) reacted specifically with antiserum prepared against purified myoepithelial cells. The purified secretory cells were unique in possessing glucose-6-phosphate dehydrogenase activity. The different cell markers not only gave independent estimates of the purity of the cell fractions, but they also may be helpful in identifying mammary cells in stages of differentiation and neoplastic transformation.
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PMID:Purification and characterization of mammary myoepithelial and secretory cells from the lactating rat. 624 56

The response of mammary myoepithelial cells to oxytocin was studied by monitoring the level of phosphorylation of the 20,000 mol wt light chain of myosin. Myoepithelial cells were obtained by collagenase dispersion of involuted rat mammary tissue. The cells were equilibrated with [32P]orthophosphate, and then stimulated with oxytocin. Phosphorylated proteins were separated by polyacrylamide gel electrophoresis, and incorporation of 32P into the proteins was detected by autoradiography. Nanomolar concentrations of oxytocin caused a 3-fold increase in the level of phosphorylation of the myosin light chain within 0.5 min. When the cells were incubated with oxytocin in a calcium-free medium, there was only a transient phosphorylation of myosin. However, readdition of calcium to these cells resulted in phosphorylation of the myosin light chain. The results suggest that calcium is involved in the intracellular events following stimulation of the cells with oxytocin.
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PMID:Phosphorylation of myosin in mammary myoepithelial cells in response to oxytocin. 707 45

The effects of culture supernatants conditioned by the growth of Staphylococcus aureus M60 on in vitro growth and functional properties of bovine mammary myoepithelial cells were examined. Myoepithelial cell proliferation was reduced by Staph. aureus M60 culture supernatants. Exposure of myoepithelial cells to culture supernatants of isogeneic mutants of Staph. aureus M60 that produced either alpha or beta toxins reduced proliferation, but to a lesser extent than supernatants from the wild type strain. Thus, alpha and beta toxins may play some role in affecting myoepithelial cell proliferation. Of the cells tested, 42% contracted following addition of oxytocin (10(-7) M) in the culture medium. Treatment of myoepithelial cells for 15 min with Staph. aureus M60 supernatants, prior to addition of oxytocin in the culture medium, increased the number of cells that contracted to 92%. Exposure of cells for 3 h to the same supernatant, prior to addition of oxytocin in the culture medium, abolished oxytocin responsiveness, had no effect on immunolocalization of actin and vimentin, but affected the localization of alpha-actinin within myoepithelial cells. Treatment of myoepithelial cells for 3 h with a combination of purified staphylococcal proteinases XVI and XVII-B abolished oxytocin responsiveness and mimicked the effect of the Staph. aureus culture supernatant. We conclude that Staph. aureus M60 culture supernatant affected proliferation and functional properties of myoepithelial cells.
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PMID:Effects of Staphylococcus aureus products on growth and function of bovine mammary myoepithelial cells in vitro. 856 28