Physiological Comparison of the Longitudinal and Circular Muscles of the Pregnant Rat Uterus

Osa, Takuro; Katase, Takashi

doi:10.2170/jjphysiol.25.153

Cited by 46 publications

(30 citation statements)

References 13 publications

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“…The functional consequences of this expression pattern are unknown, but the two muscle layers do have different embryological origins and exhibit different contractile and physiological characteristics (Osa & Katase 1975, Kawarabayashi & Osa 1976, Chow & Marshall 1981, Mlynarczyk et al 2003. Therefore, it is possible that Hsp27 has muscle layer-specific roles during pregnancy and labour.…”

Section: Hsp27 Expression During Pregnancymentioning

confidence: 99%

Small heat shock protein 27 (Hsp27) expression is highly induced in rat myometrium during late pregnancy and labour

White¹,

Williams²,

Highmore³

et al. 2005

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The underlying mechanisms that regulate uterine contractions during labour are still poorly understood. A candidate regulatory protein is heat shock protein 27 (Hsp27). It belongs to the small heat shock protein family and can regulate actin cytoskeleton dynamics, act as a chaperone, and may regulate contractile protein activation. As a result, we hypothesized that Hsp27 expression would be highly induced during late pregnancy and labour. Hsp27 mRNA expression was significantly elevated (P < 0.05) on days 17 to 22 of gestation. In addition, immunoblot analysis demonstrated that detection of total Hsp27 increased (P < 0.05) between day 21 and 1 day post-partum (PP) inclusive. Since phosphorylation of Hsp27 has been reported to be a prerequisite for smooth muscle contraction, we examined the temporal and spatial expression of Ser-15 phosphorylated Hsp27. Immunoblot analysis showed that the detection of Ser-15 phosphorylated Hsp27 significantly increased (P < 0.05) between days 19 and 23 (active labour) inclusive, in parallel with detection of total Hsp27. Immunocytochemical analysis of Ser-15 phosphorylated Hsp27 expression in situ demonstrated that phosphorylated Hsp27 in circular muscle became detectable in peri-nuclear and membrane regions on days 19 to 22, but was primarily restricted to the cytoplasm on days 23 to PP. In contrast, phosphorylated Hsp27 in longitudinal muscle was primarily detected in myocyte membranes on days 15 to 22, and then also became detectable in the cytoplasm of myocytes on days 23 and PP. Our results demonstrate that Hsp27 expression is highly upregulated during late pregnancy and labour and suggest that Hsp27 is a potential candidate contraction-associated protein.

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Section: Hsp27 Expression During Pregnancymentioning

confidence: 99%

Small heat shock protein 27 (Hsp27) expression is highly induced in rat myometrium during late pregnancy and labour

White¹,

Williams²,

Highmore³

et al. 2005

Reproduction

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“…Evidence is accumulating that the physiological and pharmacological properties of longitudinal and circular muscles of rat uterus are largely different (OsA and KATASE, 1975;KAWARABAYASHI and OSA, 1976;MASAHASHI and TOMITA, 1983). These properties also change depending on stages of pregnancy (KURIYAMA and SUZUKI, 1976a, b;KAWARABAYASHI and MARSHALL, 1981;KISHIKAWA, 1981;CHOW and MARSHALL, 1981).…”

mentioning

confidence: 99%

Effects in vitro of progesterone and estradiol-17.BETA. on the contractile and electrical responses in rat myometrium.

Osa

Ogasawara

1984

Jpn.J.Physiol

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Uterine longitudinal and circular muscles from pre-and postterm rats were studied in vitro for their contractile and electrical activities under the influence of 20-100 ,uM progesterone, 20 ,uM estradioll7R, or 20 ,uM stilbestrol. Uterine longitudinal or circular muscle strips were irrigated by Krebs solution at 37°C containing one of the hormones mentioned above, dissolved by the use of ultrasonic wave. Muscle contractions were recorded by a force displacement transducer, and electrical activities of the muscle membrane were studied using an intracellular microelectrode. At diestrus and Day 14 of pregnancy, progesterone depressed the contractions of longitudinal muscle. At pre-term, progesterone potentiated the contractions and prolongated the membrane burst discharge of longitudinal muscles, while estradiol inhibited their contractions and suppressed spike activities. At the same stage of pregnancy, both progesterone and estradiol inhibited contractions of circular muscles. At post-partum, progesterone potentiated and then depressed longitudinal muscles, while estradiol inhibited their contractions. At this stage, both progesterone and estradiol inhibited contractions of circular muscles, although vigorous spike discharges were observed. Stilbestrol depressed contractions of both longitudinal muscles from diestrus rats and longitudinal ileal muscles from a guinea pig. In view of these findings, it was deduced that these ovarian hormones exert dual action on the uterine muscle in vitro, one through changes in the membrane activity and the other through dissociation of excitation-contraction coupling.

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“…These occur in either Krebs, Tyrode, or Locke solutions (OsA et al, 1974;OSA and KATASE, 1975;OSA and FUJiNo, 1978;KANDA and KURIYAMA, 1980;KAWARABAYASHI and MARSHALL, 1981). It was also confirmed that noradrenaline causes excitatory effects in Day 21 preparations, and inhibitory effects in Day 22 preparations.…”

Section: Discussionmentioning

confidence: 72%

Changes in the adrenergic effects and membrane activity of the circular muscle of rat uterus during late pregnancy and postpartum.

Osa

Ogasawara

1984

Jpn.J.Physiol

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Circular muscle strips of rat uterus were obtained in the morning on Days 21 and 22 of pregnancy, and on the first postpartum day. Changes in the effects of noradrenaline and isoprenaline due to pregnant stage and incubation period in vitro were investigated, taking the contractile response and membrane activity as indicators. Plateau potential was dominant in Day 21 and postpartum preparations, and spike potential on Day 22. Noradrenaline (3 x 10-7, 10-g M) caused excitation in Day 21 and postpartum preparations, whereas it caused inhibition in Day 22 preparations during early exposure to Krebs solution. When contractile potentiation was caused, plateau potential was prolonged, and when contractile depression was caused the plateau potential was suppressed. By incubation in vitro with Krebs solution, a transformation of the effect of noradrenaline from excitation to inhibition was caused in Day 21 preparations, and from strong to weak inhibition in Day 22 preparations. Isoprenaline of 3 x 10-10 M concentration markedly depressed the contractile response in Day 22 preparations, whereas 10-8 M isoprenaline was not enough to suppress the spontaneous contractions in postpartum preparations.

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Physiological Comparison of the Longitudinal and Circular Muscles of the Pregnant Rat Uterus

Cited by 46 publications

References 13 publications

Small heat shock protein 27 (Hsp27) expression is highly induced in rat myometrium during late pregnancy and labour

Small heat shock protein 27 (Hsp27) expression is highly induced in rat myometrium during late pregnancy and labour

Effects in vitro of progesterone and estradiol-17.BETA. on the contractile and electrical responses in rat myometrium.

Changes in the adrenergic effects and membrane activity of the circular muscle of rat uterus during late pregnancy and postpartum.

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