Effect of Mg2+ on the binding of oxytocin to sheep myometrial cells

Pliška, V.; Albertin, Hildegard Kohlhauf

doi:10.1042/bj2770097

Cited by 13 publications

(4 citation statements)

References 21 publications

(23 reference statements)

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“…Although there have been a number of studies on the binding of oxytocin to its receptor in rat (Soloff ef al., 1979), sheep (PliSka andKohlhauf Albertin, 1991), cow (Jenner et al, 1991), and human uterus (Fuchs ef al., 1984), no detailed studies have been carried out in terms of association and dissociation kinetics. The present kinetic studies revealed that the affinity of longitudinal muscle membrane receptors for oxytocin increased through an increase in the association rate and a decrease in the dissociation rate with the progress of pregnancy.…”

Section: Discussionmentioning

confidence: 99%

Changes in kinetic properties of oxytocin receptors in longitudinal muscle membranes of rat uterus during gestation

Kaneko¹,

Kawarabayashi²,

Sugimori³

et al. 1995

J of Molecular Recognition

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Receptors of oxytocin were found to occur in the membrane fraction obtained from longitudinal muscle of pregnant rat uterus. The affinity of the membrane receptor for oxytocin increased through an increase in the association rate and a decrease in the dissociation rate during gestation. The membrane oxytocin receptor concentrations rose almost three-fold from Day 15 to Day 21. A transition of oxytocin receptors from a single class of independent sites to site-site interacted multiple binding sites, which most likely exhibit positive cooperativity during the last seven days of gestation, was observed. These results suggest that changes in the dynamics of uterine oxytocin receptors also play an important role in the onset of labor.

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Section: Discussionmentioning

confidence: 99%

Changes in kinetic properties of oxytocin receptors in longitudinal muscle membranes of rat uterus during gestation

Kaneko¹,

Kawarabayashi²,

Sugimori³

et al. 1995

J of Molecular Recognition

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“…Addition of cholesterol to the culture medium reversed a fraction of OT-receptors to the high-affinity state (K d around 1nM) [217]. The effects of divalent cations on the binding affinity of OT-R agonists are very similar to those produced by cholesterol [218]. Peptides with relatively low activity, such as 7-glycine OT became significantly more potent on uterine, but not mammary gland, receptors when the Mn 2+ concentration in the buffer bathing the uterine smooth muscle was increased [219].…”

Section: Target Structure Function Localisationmentioning

confidence: 88%

Preterm Labour: An Overview of Current and Emerging Therapeutics

Schwarz¹,

Page²

2003

CMC

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Preterm labour is a major cause of perinatal mortality and morbidity. However, during the past 40 years of clinical studies and despite the use of multiple therapeutic agents, the rate of preterm birth has not drastically declined. In 1991, it was estimated that in the US approximately 116,000 women admitted with acute episodes of preterm labour were treated each year with ritodrine, which is the first drug approved by the US FDA and still remains the standard therapy for treating preterm labour. Ritodrine (Yutopar( trade mark )) stimulates the beta(2)-adrenergic receptor throughout the body, causing an inhibitory action in different tissues that, among other side effects, also leads to an attenuation of uterine contractility. More recently, a new therapeutic agent, atosiban (Tractocile( trade mark )), a peptidic oxytocin receptor antagonist, has been introduced to the market. However, the use of the various pharmacological agents to treat preterm labour remains restricted, due to lack of uterine selectivity, low efficacy and potentially serious side effects for the mother or the foetus. Therefore, there is an urgent need to develop drugs with myometrial selectivity that would allow long-lasting inhibition of labour and prolong pregnancy up to a stage when good foetal maturation raises the chances of survival. One of the major obstacles hampering the development of new therapeutic agents is the marked inter-species difference in terms of preterm labour physiology, which complicates the preclinical evaluation of new candidate molecules in animal models of disease. In this review, the authors will provide a comprehensive update of past, current and new approaches for the management of preterm labour, including beta(2)-adrenergic agonists, calcium channel blockers, oxytocin antagonists, prostaglandin antagonists and other potential therapeutics. For each of the therapies used today, the review will cover the mechanism of action, benefit and adverse effects, and discuss the promise and potential benefits of new emerging therapeutic agents.

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“…The total number of computational cycles is (n-4)(n-5)/2, (n-3)(n-4)/2 and (n-2)(n-3)/2 for the three options [31]. The use of the full version, moreover, is occasionally associated with certain numeric difficulties.…”

Section: The Binding Isotherm Turns Then Into An Integral Formmentioning

confidence: 99%

Minireview: Multiple receptor populations: Binding isotherms and their numerical analysis

Pliška

1995

Journal of Receptors and Signal Transduction

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This paper reviews present models and methods of parameter estimation in relationships describing receptor-ligand interactions in equilibrium, as used in the author's laboratory. The state-of-the-art and the present experience can be summarized as follows: 1) Binding isotherms (relationships of bound and free/total ligand concentrations) are superpositions of several elementary terms describing the ligand binding to individual binding sites (receptors) present in the biological material investigated. The "nonspecific binding" is usually represented by a linear term. 2) The elementary terms are most frequently described by a rectangular hyperbola, Hill (power) function, or a rational function (binding of several ligand molecules to one molecule of receptor). Heterologous displacement requires specific functions which, however, can be transformed into one of the elementary terms. 3) Parameters (binding capacities, dissociation constants, Hill coefficients, etc.) can most reliably be estimated by nonlinear regression methods. However, these methods frequently fail to yield physically relevant values if initial estimates are far from "real" values, or if the data are strongly scattered. Some of the available routines (e.g., LIGAND) offer manifold tools to solve these difficulties. 4) The "affinity spectrum", a relationship between binding capacities and equilibrium constants, shows the presence of individual binding sites in the binding system in question. The spectrum can be constructed either by Fourier analysis, or by a stepwise procedure (computation of binding capacity for several dissociation constants). The former way of analysis is demanding; software tools are rare. 5) The "STEP" routine based on Hill/Scatchard linearization routines yields profiles similar to affinity spectra, but offers, in addition, values of Hill coefficients of individual binding populations. Values obtained can be used as initial estimates for nonlinear regression. 6) Selection of a suitable model, its testing, numerical procedures, statistical estimates, etc. frequently entail severe difficulties which are approached in the available software packages in different ways, none of them is usually optimal.

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Effect of Mg2+ on the binding of oxytocin to sheep myometrial cells

Cited by 13 publications

References 21 publications

Changes in kinetic properties of oxytocin receptors in longitudinal muscle membranes of rat uterus during gestation

Changes in kinetic properties of oxytocin receptors in longitudinal muscle membranes of rat uterus during gestation

Preterm Labour: An Overview of Current and Emerging Therapeutics

Minireview: Multiple receptor populations: Binding isotherms and their numerical analysis

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