Activity of circular muscle of rat uterus at different times in pregnancy

Bengtsson, Bengt; Chow, E.; Marshall, J. F.

doi:10.1152/ajpcell.1984.246.3.c216

Cited by 59 publications

(26 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In rats [22,23], sheep [15], and rhesus monkeys [34,35], spontaneous contractile activity is evident in the pregnant uterus in vivo. Further indication that this uterine activity is independent of neural or endocrine drive is suggested by synchrony in electrical and, presumably, contractile activity in myometrial tissue grafts from pregnant and nonpregnant ewes [16].…”

Section: Discussionmentioning

confidence: 99%

“…Development of high-frequency and high-amplitude contractions is the predominant sign that labor has been initiated in these species. Since agonist-induced uterine contractile activity is also augmented prior to the onset of labor [15,23], the evidence suggests that mechanical capabilities for synchronous and powerful myometrial contractions are established before the onset of labor in the murine model.…”

Section: Discussionmentioning

confidence: 99%

“…Qualitative assessment of contractility by the peripartum uterus suggested that contractile capabilities, both basal and agonist-stimulated, were enhanced at term [23]. However, changes in neither frequency nor amplitude of contractions were quantified during the period immediately before or after birth or following agonist treatment.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, in vitro myometrial responsiveness to agonists is enhanced sometime before the transition from relative quiescence to onset of labor, but neither frequency nor amplitude of contractions changes during the last 5 weeks of gestation [15]. In rats, frequent and high-amplitude contractions appear on, but not before, the day of labor-a conclusion based on in vivo electromyography [20] and intrauterine pressure recordings [21] and limited in vitro data [22][23][24]. Capabilities of the myometrium to respond to various agonists are also enhanced as pregnancy progresses.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Maturation of Spontaneous and Agonist-Induced Uterine Contractions in the Peripartum Mouse Uterus1

Mackler¹,

Ducsay²,

Veldhuis³

et al. 1999

Biology of Reproduction

View full text Add to dashboard Cite

This study tested the hypothesis that the uterus achieves maximum contractile capabilities before the onset of labor. Basal and agonist-stimulated contractions were assessed in uterine strips on Day 15 or 18 of pregnancy, the day of parturition, or 1 day postpartum (n = 4-13 per group). Spontaneous contractions were evident in all groups (n = 4-13 per gestational group); contraction frequency was greater in peripartum groups than in virgin controls ( approximately 4.6 versus 2.8/200 sec). Peak amplitude was nearly 9-fold higher on Days 15 and 18 and over 30-fold higher in the postpartum and 1 day postpartum groups than in nonpregnant mice. Maximum frequency and peak amplitude were achieved in response to 10(-6) to 10(-8) M oxytocin or arginine vasopressin (OT(max) or AVP(max)). Frequency of contractions in response to OT(max) peaked on Day 18 and then declined. Contraction amplitude increased 5-fold on Day 15, declined on the day of birth (equivalent to nonpregnant level), then rebounded to peak on postpartum Day 1. AVP(max) similarly increased frequency and amplitude of contractions, except that maximum contraction amplitude occurred postpartum. Thus, an endogenous oscillator, residing in the uterus, sustains high basal and agonist-induced contraction frequency during pregnancy. Although acceleration of this pacemaker occurred before term, the data suggest that peripartum increases in contraction amplitude characterize the transition to the powerful synchronous contractions of parturition.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Maturation of Spontaneous and Agonist-Induced Uterine Contractions in the Peripartum Mouse Uterus1

Mackler¹,

Ducsay²,

Veldhuis³

et al. 1999

Biology of Reproduction

View full text Add to dashboard Cite

show abstract

“…Throughout gestation the electrical activity of L is characterized by bursts of repetitive spikes that cause strong but infrequent contractions until just before and during delivery when the contractions of L and C are similar (Bengtsson et al 1984). …”

Section: Introductionmentioning

confidence: 99%

Comparison of the Activity of Circular and Longitudinal Myometrium From Pregnant Rats: Co‐ordination Between Muscle Layers

Tomiyasu

Chen

Marshall

1988

Clin Exp Pharma Physio

Self Cite

View full text Add to dashboard Cite

1. Contractions and electrical activity were recorded from isolated segments of longitudinal (L) and circular (C) myometrium from rats on gestation days 16-17 and 21 before and during parturition. 2. The segments were arranged so that the activity of the two layers could be monitored simultaneously and independently. 3. Out of the 15 preparations from days 16-17, 13 showed no co-ordination of activity between the layers. In the other two preparations a large contraction of C occasionally initiated a contraction of L. Surgical separation of the layers disrupted the co-ordination and L then developed its independent rhythm. 4. On day 21 before delivery, eight of 10 preparations exhibited 1:1 co-ordination of activity between the two layers, but C did not consistently pace L. The pacing shifted from one layer to the other several times during an experiment. 5. During parturition there was a 1:1 co-ordination of activity in all 10 preparations examined. In nine of these L initiated the activity of the C. Surgical separation of the layers disrupted the co-ordination and C developed its independent rhythm. In one the pacing shifted from one layer to the other several times during the experiment. 6. In all cases where co-ordination between the layers was observed it was myogenic and apparently related to the spread of action potentials between the two muscles.

show abstract

The Role of Membrane Potential in the Control of Uterine Motility

Parkington

Coleman

1990

Uterine Function

View full text Add to dashboard Cite

Activity of circular muscle of rat uterus at different times in pregnancy

Abstract: the change in circular muscle activity during pregnancy is related to electrical events and not to contractile ability.

Cited by 59 publications

References 9 publications

Maturation of Spontaneous and Agonist-Induced Uterine Contractions in the Peripartum Mouse Uterus1

Maturation of Spontaneous and Agonist-Induced Uterine Contractions in the Peripartum Mouse Uterus1

Comparison of the Activity of Circular and Longitudinal Myometrium From Pregnant Rats: Co‐ordination Between Muscle Layers

The Role of Membrane Potential in the Control of Uterine Motility

Contact Info

Product

Resources

About