scholarly journals Influence of oxytocin receptor single nucleotide sequence variants on contractility of human myometrium: an in vitro functional study

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
F. Füeg ◽  
S. Santos ◽  
C. Haslinger ◽  
B. Stoiber ◽  
L. Schäffer ◽  
...  
Keyword(s):  
Mode Of Delivery ◽  
Oxytocin Receptor ◽  
Functional Study ◽  
Human Myometrium ◽  
Sequence Variants ◽  
Organ Bath ◽  
Single Nucleotide ◽  
Allele Distribution ◽  
Stimulation Of

Abstract Background Oxytocin receptor (OXTR) gene variants have been shown to affect the prevalence of preterm birth, mode of delivery and oxytocin (OXT) requirements for labor induction and augmentation. We hypothesized that this might be associated with different myometrium responses to oxytocin. Our aim was to investigate the influence of a selection of eight OXTR gene single nucleotide variants on oxytocin-induced stimulation of human myometrium contractility in vitro. Methods Human myometrium biopsies were collected during elective cesarean sections at term, if patients had given informed consent. Myometrial strips were submerged under tension in an organ bath and allowed to contract; the remaining material was stored at − 80 °C for further determination of relevant genetics and mRNA level. The area under the curve (AUC) of all contractions taking place in the absence of OXT and of those occurring upon OXT addition (for 30 min each) was measured. OXT stimulation, defined as the ratio between AUC measurements after OXT addition and those in the absence of OXT was calculated for each strip. TaqMan™ Assays were used to detect the allele distribution of the eight OXTR variants and to determine the relative amounts of OXTR-mRNA in the samples. For each variant, oxytocin stimulation of contractility was compared between samples homozygous for the reference allele (reference group) and samples with at least one variant allele (variant group) by linear regression. Results Sixty samples were included in the present study. For rs1042778, rs11706648, rs4686301, rs53576, rs237895, and rs237902, OXT stimulation was similar in the reference and in the variant groups. However, the values of OXT stimulation differed significantly between the reference and the variant groups for rs4686302 (3.1 vs. 4.1 times; p = 0.022) and rs237888 (3.2 vs. 5.5 times; p = 0.001). No significant differences between the levels of OXTR-mRNA in the various reference and corresponding variant groups were detected. Conclusions Patients with variant alleles of rs237888 and/or rs4686302 may be more sensitive to oxytocin stimulation, explaining why these sequence variants have been associated with lower cesarean section prevalence and premature birth, respectively.

scholarly journals In Vitro Effects of Propofol on Gravid Human Myometrium

2008 ◽  
Vol 36 (6) ◽  
pp. 802-806 ◽  
Author(s):  
A. S. Thind ◽  
R. J. Turner
Keyword(s):  
Isometric Tension ◽  
Human Myometrium ◽  
Organ Bath ◽  
Dependent Manner ◽  
Uterine Contractility ◽  
Time Curve ◽  
Lower Segment Caesarean Section ◽  
Uterine Muscle ◽  
In Vitro Effects

The aim of this study was to evaluate the direct effect of propofol (di-isopropyl phenol) on the contractile properties of gravid human uterine muscle. Six specimens of uterine muscle were obtained from term parturients undergoing elective lower segment caesarean section. Small strips (1 × 2 x 12 mm) of muscle were prepared and suspended in an organ bath containing oxygenated Kreb's solution at 36.5°C. Following preparation, spontaneous regular contractions developed at a rate of one contraction every six to 10 minutes. Force of contraction was recorded continuously using an isometric tension transducer. Following baseline measurements, propofol was introduced into the bath at concentrations corresponding to 2 /μg/ml, 5 /μg/ml and 8 /μg/ml. The specimens were also exposed to intralipid in concentrations equivalent to that found in the 8 μ/ml solution of propofol to determine whether this additive influenced uterine contractility. Contractility (defined as area under the tension/time curve) was decreased to 89 ± 6.5% of control at 2 μg/ml 53±4.3% at 5 μ/ml and 45 ± 4.1% at 8 μg/ml. This decrease in contractility was statistically significant at concentrations >2 μg/ml. Intralipid did not significantly affect uterine contractility. The results of this study show that propofol decreases isolated human uterine muscle contractility in a dose-dependent manner.

Structural and functional study of control of canine tracheal smooth muscle

1980 ◽  
Vol 238 (1) ◽  
pp. C27-C33 ◽  
Author(s):  
M. S. Kannan ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Electrical Field Stimulation ◽  
Sympathetic Nerves ◽  
Tracheal Smooth Muscle ◽  
Functional Study ◽  
Field Stimulation ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
Stimulation Of

The structural bases for myogenic and neurogenic control of canine tracheal smooth muscle were studied. At optimum lengths, strips of muscle showed insignificant neurogenic or myogenic tone. Atropine and/or tetrodotoxin blocked the contractile responses elicited on electrical field stimulation of intrinsic nerves. After raising the tone with tetraethylammonium ion and in the presence of atropine, field stimulation of nerves caused a relaxation, a major component of which was blocked by propranolol and/or tetrodotoxin, suggesting an effect mediated through interaction of mediator released from sympathetic nerves with beta-adrenergic receptors. Electron microscopic studies revealed gap junctions between extensions of smooth-muscle cells and a sparse innervation. The axonal varicosities, corresponding to cholinergic (predominantly) and adrenergic (occasionally) nerves, were seen predominantly in the clefts between cell bundles. The physiological responses were compared with the morphological features. Although this muscle exhibits multiunit behavior in vitro, implying that nerves initiate the coordinate activity, its ultrastructural features suggest a potential for single-unit behavior.

In Vitro Comparative Effect of Carbetocin and Oxytocin in Pregnant Human Myometrium with and without Oxytocin Pretreatment

2016 ◽  
Vol 124 (2) ◽  
pp. 378-386 ◽  
Author(s):  
Naida M. Cole ◽  
Jose C. A. Carvalho ◽  
Magda Erik-Soussi ◽  
Nivetha Ramachandran ◽  
Mrinalini Balki
Keyword(s):  
Dose Response ◽  
Salt Solution ◽  
Area Under The Curve ◽  
Primary Outcome Measure ◽  
Human Myometrium ◽  
Control Group ◽  
Organ Bath ◽  
Motility Index ◽  
Elective Cesarean

Abstract Background The purpose of this study was to compare in vitro contractile effects of oxytocin and carbetocin on human term pregnant myometrium with and without oxytocin pretreatment. Methods This laboratory investigation was conducted on myometrial samples from women undergoing elective cesarean deliveries. The samples were dissected into four strips and suspended in individual organ bath chambers containing physiologic salt solution. After equilibration, they were pretreated with oxytocin 10−5 M (experimental group) or physiologic salt solution (control group) for 2 h and then subjected to dose–response testing with increasing concentrations of oxytocin or carbetocin (10−10 to 10−5 M). The amplitude, frequency, motility index (amplitude × frequency), and area under the curve of contractions were recorded and analyzed during the equilibration and dose–response periods. Comparisons were made between oxytocin-induced and carbetocin-induced contractions in control and oxytocin-pretreated groups. Motility index was the primary outcome measure. Results Sixty-three experiments were performed (carbetocin, n = 31; oxytocin, n = 32) on samples from 18 women. The motility index of contractions (√g.contractions/10 min) produced by oxytocin was significantly higher than carbetocin in both control (regression-estimated difference, 0.857; 95% CI, 0.290 to 1.425; P = 0.003) and oxytocin-pretreated (0.813; 0.328 to 1.299; P = 0.001) groups. The motility index was significantly lower in oxytocin-pretreated groups than their respective controls for both oxytocin (−1.040; −1.998 to −0.082; P = 0.03) and carbetocin (−0.996; −1.392 to −0.560; P < 0.001). Conclusions In vitro contractions produced by oxytocin are superior to carbetocin in human myometrium with or without oxytocin pretreatment. Oxytocin pretreatment results in attenuation of contractions induced by both oxytocin and carbetocin.

scholarly journals The Effect of an Oxytocin Receptor Antagonist (Retosiban, GSK221149A) on the Response of Human Myometrial Explants to Prolonged Mechanical Stretch

Endocrinology ◽  
2015 ◽  
Vol 156 (10) ◽  
pp. 3511-3516 ◽  
Author(s):  
Alexandros A. Moraitis ◽  
Yolande Cordeaux ◽  
D. Stephen Charnock-Jones ◽  
Gordon C. S. Smith
Keyword(s):  
Preterm Birth ◽  
Receptor Antagonist ◽  
Multiple Pregnancy ◽  
Mechanical Stretch ◽  
Inhibitory Effect ◽  
Oxytocin Receptor ◽  
Human Myometrium ◽  
Spontaneous Preterm Birth ◽  
Myometrial Contractility ◽  
Stimulation Of

Multiple pregnancy is a major cause of spontaneous preterm birth, which is related to uterine overdistention. The objective of this study was to determine whether an oxytocin receptor antagonist, retosiban (GSK221149A), inhibited the procontractile effect of stretch on human myometrium. Myometrial biopsies were obtained at term planned cesarean delivery (n = 12). Each biopsy specimen was dissected into 8 strips that were exposed in pairs to low or high stretch (0.6 or 2.4 g) in the presence of retosiban (1 μM) or vehicle (dimethylsulfoxide) for 24 hours. Subsequently, we analyzed the contractile responses to KCl and oxytocin in the absence of retosiban. We found that incubation under high stretch in vehicle alone increased the response of myometrial explants to both KCl (P = .007) and oxytocin (P = .01). However, there was no statistically significant effect of stretch when explants were incubated with retosiban (P = .3 and .2, respectively). Incubation with retosiban in low stretch had no statistically significant effect on the response to either KCl or oxytocin (P = .8 and >.9, respectively). Incubation with retosiban in high stretch resulted in a statistically significant reduction (median fold change, interquartile range, P) in the response to both KCl (0.74, 0.60–1.03, P = .046) and oxytocin (0.71, 0.53–0.91, P = .008). The greater the effect of stretch on explants from a given patient, the greater was the inhibitory effect of retosiban (r = −0.65, P = .02 for KCl and r= −0.73, P = .007 for oxytocin). These results suggest that retosiban prevented stretch-induced stimulation of human myometrial contractility. Retosiban treatment is a potential approach for preventing preterm birth in multiple pregnancy.

A Bufadienolide-Enriched Fraction of Bryophyllum pinnatum Inhibits Human Myometrial Contractility In Vitro

Planta Medica ◽  
2018 ◽  
Vol 85 (05) ◽  
pp. 385-393 ◽  
Author(s):  
Stefanie Santos ◽  
Christian Haslinger ◽  
Kristian Klaic ◽  
Maria Faleschini ◽  
Mónica Mennet ◽  
...  
Keyword(s):  
Cell Viability ◽  
Area Under The Curve ◽  
Progressive Increase ◽  
Human Myometrium ◽  
Organ Bath ◽  
Relaxant Effect ◽  
System Cell ◽  
Myometrial Contractility ◽  
Bryophyllum Pinnatum

Abstract Bryophyllum pinnatum has been used since the 1970s to prevent premature labour, first in anthroposophic hospitals and, more recently, also in the main Swiss perinatal centres. However, it is not known which compounds in B. pinnatum leaves contribute to the tocolytic effect. Here we studied the effects of a flavonoid-enriched fraction, the corresponding flavonoid aglycon mixture, a bufadienolide-enriched fraction, and B. pinnatum leaf press juice on human myometrial contractility in vitro. The strength (area under the curve and amplitude) and frequency of contractions were recorded using strips of human myometrium mounted in an organ bath system. Cell viability assays were performed with the human myometrium hTERT-C3 and PHM1 – 41 cell lines. Repeated addition of the flavonoid-enriched fraction, flavonoid aglycon mixture, bufadienolide-enriched fraction, or B. pinnatum leaf press juice led to a progressive decrease of contraction strength, without jeopardising the vitality of myometrium strips. The bufadienolide-enriched fraction was the most active, since 1 µg/mL of the bufadienolide-enriched fraction lowered the area under the curve to 40.1 ± 11.8% of the initial value, whereas 150 µg/mL of the flavonoid-enriched fraction, 6.2 µg/mL of the flavonoid aglycon mixture, and 10 µg/mL of the B. pinnatum leaf press juice were required to achieve comparable inhibition. A progressive increase of contraction frequency was observed, except in the case of the flavonoid aglycon mixture, which did not affect frequency. None of the test substances decreased myometrial cell viability, even at concentrations of 500 µg/mL of the flavonoid-enriched fraction, 40 µg/mL of the flavonoid aglycon mixture, 3.8 µg/mL of the bufadienolide-enriched fraction, and 75 µg/mL of the B. pinnatum leaf press juice, i.e., higher than those used in the myometrium experiments. Given the concentrations of flavonoids in the flavonoid-enriched fraction and B. pinnatum leaf press juice, and of bufadienolides in the bufadienolide-enriched fraction and B. pinnatum leaf press juice, it appears that bufadienolides may be mainly responsible for the relaxant effect.

Spontaneous Human Myometrial Contractility in the Third Trimester of Pregnancy in Relation to Past Mode of Delivery

2019 ◽  
Author(s):  
Gillian A. Ryan ◽  
Sarah M. Nicholson ◽  
Denis J. Crankshaw ◽  
John J. Morrison
Keyword(s):  
Vaginal Delivery ◽  
Contractile Activity ◽  
Mode Of Delivery ◽  
Maximum Amplitude ◽  
Human Myometrium ◽  
Success Rates ◽  
Uterine Contractions ◽  
Group 3 ◽  
Group 2

Abstract Objective It is well established that women with a previous vaginal delivery have higher success rates in relation to vaginal birth after cesarean than those without. The aim of this study was to examine the effect of past mode of delivery on contractile parameters of human myometrium in vitro. Study Design Myometrial strips were excised from 64 women at cesarean delivery (CD) and recordings of spontaneous contractile activity analyzed and compared across three clinical groups: (1) women with no previous delivery (Group 1); (2) women with CD only (Group 2); and (3) women with a history of vaginal delivery and CD (Group 3). Results Myometrial samples from women in Group 3, women who had a previous vaginal delivery, had a significantly greater maximum amplitude of contractions (p < 0.05), a greater force (mean contractile force) of contractions (p < 0.01), and a faster rate of rise (p < 0.01) and relaxation of contractions (p < 0.05) than those in Groups 1 and 2. Conclusion Many of the functional parameters of human uterine contractions are altered, or enhanced, in the women who have had a previous vaginal delivery, when compared with those without. This may partly explain the clinical differences observed in labor.

scholarly journals Bryophyllum pinnatum enhances the inhibitory effect of atosiban and nifedipine on human myometrial contractility: an in vitro study

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
S. Santos ◽  
C. Haslinger ◽  
M. Mennet ◽  
U. von Mandach ◽  
M. Hamburger ◽  
...  
Keyword(s):  
Cell Viability ◽  
Therapeutic Potential ◽  
Inhibitory Effect ◽  
Human Myometrium ◽  
Anthroposophic Medicine ◽  
Organ Bath ◽  
Amplitude Data ◽  
Myometrial Contractility ◽  
Bryophyllum Pinnatum

Abstract Background The herbal medicine Bryophyllum pinnatum has been used as a tocolytic agent in anthroposophic medicine and, recently, in conventional settings alone or as an add-on medication with tocolytic agents such as atosiban or nifedipine. We wanted to compare the inhibitory effect of atosiban and nifedipine on human myometrial contractility in vitro in the absence and in the presence of B. pinnatum press juice (BPJ). Methods Myometrium biopsies were collected during elective Caesarean sections. Myometrial strips were placed under tension into an organ bath and allowed to contract spontaneously. Test substances alone and at concentrations known to moderately affect contractility in this setup, or in combination, were added to the organ bath, and contractility was recorded throughout the experiments. Changes in the strength (measured as area under the curve (AUC) and amplitude) and frequency of contractions after the addition of all test substances were determined. Cell viability assays were performed with the human myometrium hTERT-C3 and PHM1–41 cell lines. Results BPJ (2.5 μg/mL), atosiban (0.27 μg/mL), and nifedipine (3 ng/mL), moderately reduced the strength of spontaneous myometrium contractions. When BPJ was added together with atosiban or nifedipine, inhibition of contraction strength was significantly higher than with the tocolytics alone (p = 0.03 and p < 0.001, respectively). In the case of AUC, BPJ plus atosiban promoted a decrease to 48.8 ± 6.3% of initial, whereas BPJ and atosiban alone lowered it to 70.9 ± 4.7% and to 80.9 ± 4.1% of initial, respectively. Also in the case of AUC, BPJ plus nifedipine promoted a decrease to 39.9 ± 4.6% of initial, at the same time that BPJ and nifedipine alone lowered it to 78.9 ± 3.8% and 71.0 ± 3.4% of initial. Amplitude data supported those AUC data. The inhibitory effects of BPJ plus atosiban and of BPJ plus nifedipine on contractions strength were concentration-dependent. None of the test substances, alone or in combination, decreased myometrial cell viability. Conclusions BPJ enhances the inhibitory effect of atosiban and nifedipine on the strength of myometrial contractions, without affecting myometrium tissue or cell viability. The combination treatment of BPJ with atosiban or nifedipine has therapeutic potential.

Peripheral neural input to neurons of the stellate ganglion in dog

1982 ◽  
Vol 242 (3) ◽  
pp. R237-R243
Author(s):  
Z. J. Bosnjak ◽  
J. L. Seagard ◽  
J. P. Kampine
Keyword(s):  
Electrical Stimulation ◽  
Action Potentials ◽  
Stellate Ganglion ◽  
Afferent Input ◽  
In Vivo Studies ◽  
Organ Bath ◽  
Efferent Nerve ◽  
Stimulation Of

In vitro and in vivo studies were conducted on the stellate ganglion (SG) of the dog by recording action potentials from its nerves and its neurons. For in vitro preparations, the SG and its nerve trunks were dissected from the animal and secured in an organ bath. Peripheral input to the SG was produced by electrical stimulation of the ventral ansa subclavia (VA), dorsal ansa subclavia (DA), and stellate cardiac nerve (SC) in 15 ganglion preparations studied in vitro. Electrical stimulation of the VA elicited action potentials recorded at the DA. This conducting pathway did not involve direct anatomic continuity, since the evoked potentials were blocked by injection of hexamethonium chloride into the SG. Most neurons in the SG received synaptic input from fibers of both central and peripheral origin. In 12 in vivo preparations, all nerves to the SG except the VA were cut. When peripheral sympathetic afferent input to the SG was increased, some of the postganglionic fibers of the dissected DA exhibited an increase in efferent nerve discharge. This response was also blocked by hexamethonium chloride. These results indicate that some of the functions of the SG might be independent of the central nervous system.

scholarly journals Phospholipase C-δ1 and oxytocin receptor signalling: evidence of its role as an effector

1998 ◽  
Vol 331 (1) ◽  
pp. 283-289 ◽  
Author(s):  
Eu-Suk PARK ◽  
Jong Hyun WON ◽  
Kee Jung HAN ◽  
Pann-Ghill SUH ◽  
Sung Ho RYU ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Oxytocin Receptor ◽  
Signalling Pathway ◽  
Human Myometrium ◽  
Signal Molecules ◽  
Receptor Signalling ◽  
Tightly Coupled ◽  
Oxytocin Antagonist ◽  
Stimulation Of

Although the oxytocin receptor modulates intracellular Ca2+ ion levels in myometrium, the identities of signal molecules have not been clearly clarified. Our previous studies on oxytocin receptor signalling demonstrated that 80 kDa Ghα is a signal mediator [Baek, Kwon, Lee, Kim, Muralidhar and Im (1996) Biochem. J. 315, 739–744]. To elucidate the effector in the oxytocin receptor signalling pathway, we evaluated the oxytocin-mediated activation of phospholipase C (PLC) by using solubilized membranes from human myometrium and a three-component preparation containing the oxytocin receptor–Ghα–PLC-δ1 complex. PLC-δ1 activity in the three-component preparation, as well as PLC activity in solubilized membranes, was increased by oxytocin in the presence of Ca2+ and activated Ghα (GTP-bound Ghα). Furthermore the stimulated PLC-δ1 activity resulting from activation of Ghα via the oxytocin receptor was significantly attenuated by the selective oxytocin antagonist desGly-NH2d(CH2)5[Tyr(Me)2,Thr4]ornithine vasotocin or GDP. Consistent with these observations, co-immunoprecipitation and co-immunoadsorption of PLC-δ1 in the three-component preparation by anti-Gh7α antibody resulted in the PLC-δ1 being tightly coupled to activated Ghα on stimulation of the oxytocin receptor. These results indicate that PLC-δ1 is the effector for Ghα-mediated oxytocin receptor signalling.

scholarly journals Identification, localization and functional in vitro and in vivo activity of oxytocin receptor in the rat penis

2005 ◽  
Vol 184 (3) ◽  
pp. 567-576 ◽  
Author(s):  
X H Zhang ◽  
S Filippi ◽  
L Vignozzi ◽  
A Morelli ◽  
R Mancina ◽  
...  
Keyword(s):  
Corpus Cavernosum ◽  
Oxytocin Receptor ◽  
Rt Pcr ◽  
Binding Studies ◽  
Selective Agonist ◽  
Rabbit Corpus Cavernosum ◽  
Stimulation Of ◽  
Male Genital

We recently found that the oxytocin receptor (OTR) is expressed in the human and rabbit corpus cavernosum and mediates contractility in vitro. The present study extended our investigations to the rat, and explored whether OTR regulates penile detumescence in vivo. Real-time RT-PCR quantitatively characterized the distribution of OTR mRNA in the male genital tract. Specific transcripts for OTR were expressed in all the tissues investigated. Penile expression of OTR was comparable to that observed in testis and prostate. Western blot analysis detected a single band of the expected molecular mass for OTR in all tissues examined, including rat penis. Expression of OTR protein in rat penile extracts was further confirmed by binding studies, using the OTR selective radiolabeled ligand 125I-OTA (Kd=17 ± 6.5 pM, Bmax=15.7 ± 5 fmoles/mg protein). OTR was immunolocalized to the endothelial and smooth muscle compartments of cavernous spaces and blood vessels. In rat corpus cavernosum strips, oxytocin (OT) and an OTR selective agonist ([Thr4,Gly7]OT) induced identical increases in tension, while different vasopressin agonists were less active. In vivo, OT intra-cavernous injection (ICI) dose-dependently inhibited intracavernous pressure (ICP) increase elicited by either electrical stimulation of the cavernous nerve or ICI of papaverine with similar IC50s (117.7 ± 37 mU). The OTR antagonist, atosiban, counteracted the contractile effect of OT both in vitro and in vivo. Atosiban alone significantly increased ICP at lower stimulation frequencies (2 Hz=P<0.001 and 4 Hz=P<0.05 vs control), but not at the maximal frequency (16 Hz). Our data showed that OTR is present in the rat penis and mediates contractility both in vitro and in vivo, therefore suggesting a role for OT in maintaining penile detumescence.

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