Role of the sodium-calcium exchange mechanism and the effect of magnesium on sodium-free and high potassium contractures in pregnant human myometrium
Article Abstract:
One of two cellular mechanisms appears to play an important role in inducing relaxation of the contracting uterine muscle. Small strips of uterine muscle were removed from 74 pregnant women at the time of cesarean section. They were suspended in culture medium. Contractions were induced and the effect of various reagents were tested to see which of the two possible relaxation mechanisms could be inhibited. Calcium ions must be removed from the muscle cell in order to induce relaxation. This can happen via a calcium pump or via an exchange of sodium ions for calcium ions. Magnesium sometimes substitutes far sodium in the reactions causing an inhibition of contraction. The two mechanisms have distinct patterns when the rate of relaxation or contraction are charted over time.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1995
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Gap junction currents in cultured muscle cells from human myometrium
Article Abstract:
The propagation of electrical activity across gap junctions between muscle cells conducts the force of contraction of the uterus for childbirth. Researchers examined gap junction currents in muscle cells from human uterine myometrium, and determined that the average junctional conductance between cells is approximately 23 nanosiemens. Electrical conductance in myometrial cells can be completely blocked with halothane anesthetic. Connexin43 is an important functional component of myometrial gap junctions.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1998
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The initiation, continuation, and termination of spontaneous epidodes of circus movements in the pregnant myometrium of the rat
Article Abstract:
Uterine contractions during labor may not be well-coordinated. Researchers took samples of uterine tissue from pregnant rats and attached electrodes to monitor the activity of the cells. Twenty-two episodes of circus movements were recorded. These movements occur when an electrical impulse does not travel the entire length of the uterus, but goes around in circles. The movements lasted an average of two seconds and six revolutions. If this happens in the human uterus, it could produce weak contractions.
Publication Name: American Journal of Obstetrics and Gynecology
Subject: Health
ISSN: 0002-9378
Year: 1998
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