Effect of Indomethacin and Aspirin on Uterine Activity in Pregnant Rats: Comparison of Circular and Longitudinal Muscle1

Anderson, Gail S.; Kawarabayashi, Tatsuhiko; Marshall, J. F.

doi:10.1095/biolreprod24.2.359

Cited by 51 publications

(34 citation statements)

References 21 publications

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“…The circular muscles give off plateau potential during midpregnancy, whereas spike potentials during delivery (OSA and FujiNo, 1978;KISHIKAWA 1981;ANDERSON et al, 1981). The spike activity of circular muscle at term is due to a decrease in the amplitude of plateau potential at least in part.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, it is more likely that a mechanism which is responsible for the generation of spike potentials evolved towards the end of pregnancy. A recent report indicates that administration of indomethacin to pregnant rat causes a delayed parturition, and in this situation the burst of spike activity does not develop in circular muscle (ANDERSON et al, 1981). Therefore, it is probable that the generation of spikes in the circular muscle is a prerequisite for the performance of delivery under the influence of ovarian steroid hormones.…”

Section: Discussionmentioning

confidence: 99%

“…The membrane activity of circular muscle of pregnant rat uterus undergoes a noticeable change i. e. plateau potential dominates during midpregnancy and the membrane activity proceeds into spike potentials at term (OsA and FUJiNO, 1978;KISHIKAWA, 1981;ANDERSON et al, 1981). Therefore, it seemed of interest to investigate the stabilizing action of Mg ions which may differ depending on pregnant days.…”

mentioning

confidence: 99%

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Effects of magnesium on the membrane activity and contraction of the circular muscle of rat myometrium during late pregnancy.

Osa

Ogasawara

1983

Jpn.J.Physiol

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Comparative effects of Mg were studied on circular muscle strips of pregnant rat myometrium near term and during delivery. Frequency and amplitude of spontaneous contraction were markedly depressed by adding 0.6 mM Mg to Mg-free Krebs solution in the muscle strips taken in the morning of Days 19 and 22 of pregnancy. Frequency decreased, whereas the amplitude was not depressed by 0.6 mM Mg in muscle strips taken during delivery. Plateau potential dominated in the circular muscle taken in the morning on Days 19 and 22, and it was depressed by Mg, leaving the evoked spike potential nearly unaffected. Burst of spike potentials dominated in the circular muscle during delivery, and 0.6 mM Mg did not affect the burst discharge. In contrast to the variable effects of 0.6 mM Mg on the polarized muscle strips of different pregnant stages, application of Mg (0.6-3.6 mM) caused commonly a potentiation of tonic contraction of K-contracture generated in muscle strips of any pregnant stage. Prolonged perfusion with Mg-free Krebs solution (several hours) of the muscle strip taken in the morning on Day 22 caused a transformation of membrane activity from a plateau dominant type to a spike dominant one. With the same procedure, the depressant effect of Mg on phasic contractions was progressively decreased.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of magnesium on the membrane activity and contraction of the circular muscle of rat myometrium during late pregnancy.

Osa

Ogasawara

1983

Jpn.J.Physiol

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“…For example, during the progress of gestation, the resting membrane potential of longitudinal muscle cells of the rat myometrium inceases up to the last stage of gestation and decreases at term (Casteels & Kuriyama, 1965). The shape of the action potential in both longitudinal and circular muscles of the myometrium also changes during gestation, and shapes of the action potential differ between the longitudinal and circular muscle membrane during gestation, except for the last stage and during parturition (Kawarabayashi & Osa, 1976; Osa & Kawarabayashi, 1977;Osa & Watanabe, 1978;Anderson et al, 1981;Osa et al, 1981;. These changes in membrane properties may modify the Ca-influx of uterine smooth muscle during gestation.…”

Section: Introductionmentioning

confidence: 99%

Changes in the mechanical properties of the longitudinal and circular muscle tissues of the rat myometrium during gestation

Izumi

1985

British J Pharmacology

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1 Changes in the mechanical properties of the longitudinal and circular muscle tissues of the rat myometrium during gestation were investigated. 2 In isolated longitudinal and circular muscles of the rat myometrium, spontaneous contractions and contractions per unit cross-sectional area induced by 128 mM K and I x 10-5 M acetylcholine (ACh) increased with the progress of gestation. These increases appeared in longitudinal muscles to a greater extent than in circular muscles. 3 ACh induced the largest contraction for both intact muscle tissues, at all stages ofgestation. In both muscle layers, the ACh-induced contraction reached the same amplitude as the I x IO-5 M Ca-induced contraction of skinned muscles, except for the longitudinal muscle at the 22nd day of gestation. 4 In Ca-free solution containing 2 mM EGTA, ACh produced contraction in both intact muscle tissues at all stages and the amplitude was increased during the progress of gestation, whereas the Kinduced and spontaneous contractions ceased. 5 In saponin-treated skinned muscles of both layers, the free Ca concentration required to produce contraction was lowered, the maximum amplitudes of the contraction were increased and the pCatension relationships shifted to the left during the progress of gestation. 6 The results indicate that during the progress of gestation, Ca sensitivity of the contractile proteins and mechanical responses to agonists increased and that the properties of the intracellular Ca store site were also altered in both muscle layers.

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“…Involvement of endogenous prostaglandins in controlling the electrical and mechanical properties of uterus has also been demonstrated (Anderson, Kawarabayashi & Marshall, 1981). The effects of endogenous prostaglandin biosynthesis in relation to the ATP-induced depolarization were investigated using tissues treated with indomethacin which is a potent inhibitor of prostaglandin biosynthesis (Flower, 1974).…”

Section: Atp-induced Depolarization Of the Membranementioning

confidence: 99%

Electrical responses of smooth muscle cells of the mouse uterus to adenosine triphosphate.

Ninomiya¹,

Suzuki²

1983

The Journal of Physiology

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SUMMARY1. Electrical responses of the smooth muscle cells to ATP were recorded in the longitudinal muscle of mouse myometrium, using intracellular micro-electrodes.2. ATP (> 10-7 M) dose-dependently produced a biphasic change in the membrane potential, an initial hyperpolarization (20-30 see) and then a depolarization. This effect of ATP was observed in all stages of gestation. The initial hyperpolarization was more quickly desensitized than the depolarization.3. Application of ATP for a short period (10 see) produced only the initial hyperpolarization; the amplitude was dose-dependently increased.4. During the ATP-induced hyperpolarization and the depolarization, generation of spike potentials was suppressed and enhanced, respectively. Strong outward current restored the spike generation during hyperpolarization.5. During the ATP-induced hyperpolarization, the membrane resistance was decreased. The amplitude of the hyperpolarization was increased in low [K]o solution and decreased in high [K]o solutions.6. Pre-treatment with TEA (1 mM), procaine (1 mM), 4-aminopyridine (0 5 mM) or apamin (2 x 10-7 M) did not, but TEA (5-10 mM) did suppress the ATP-induced hyperpolarization. Involvement of endogenous catecholamines, cyclic AMP, prostaglandins or acetylcholine in the ATP responses was ruled out.7. During the ATP-induced depolarization, the membrane resistance was reduced. In low [Na]0 solutions, the muscle membrane was depolarized and the amplitude of ATP-induced depolarization was reduced. In sodium-free solution, ATP produced only the initial hyperpolarization.8. It was concluded that the electrical responses ofthe smooth muscle cells of mouse myometrium to ATP consist of two components: an initial hyperpolarization with increase in the potassium conductance and a depolarization with increase in the sodium conductance.

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Effect of Indomethacin and Aspirin on Uterine Activity in Pregnant Rats: Comparison of Circular and Longitudinal Muscle1

Abstract: This study compares the effects of two inhibitors of prostaglandin synthesis, indomethacin and aspirin, on the longitudinal muscle (LM) and circular muscle (CM) of the rat uterus.

Cited by 51 publications

References 21 publications

Effects of magnesium on the membrane activity and contraction of the circular muscle of rat myometrium during late pregnancy.

Effects of magnesium on the membrane activity and contraction of the circular muscle of rat myometrium during late pregnancy.

Changes in the mechanical properties of the longitudinal and circular muscle tissues of the rat myometrium during gestation

Electrical responses of smooth muscle cells of the mouse uterus to adenosine triphosphate.

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