Gap junction formation and regulation in myometrium

Garfield, Robert E.; Merrett, Darren; Grover, Ashok K.

doi:10.1152/ajpcell.1980.239.5.c217

Cited by 113 publications

(50 citation statements)

References 19 publications

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“…Indeed, several studies have shown the sensitivity of the myometrium to uterine volume (5) and to stretch (7,30). Another potential complication is the fact that gap junctions that electrically connect myometrial cells may form spontaneously in vitro, which may improve electrical coupling and affect electrical propagation (14,29). Finally, even if a stable pacemaker had been found, there is evidence to suggest that this may not be stable during longer recording periods (26).…”

Section: Discussionmentioning

confidence: 99%

Patterns of electrical propagation in the intact pregnant guinea pig uterus

Lammers¹,

Mirghani²,

Stephen³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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Previous studies have reported on propagation of individual spikes in isolated segments of the pregnant uterus, but there is no information on patterns of spike propagation in the intact organ. There is also no information on propagation of myometrial burst. The aim of this study was to record, at high resolution, patterns of propagation of electrical activities in the pregnant uterus. Sixteen timed-pregnant guinea pigs were euthanized at term, and their uteruses isolated. Fetuses were removed and replaced by an equal amount of Tyrode. A 240-electrode array was positioned at various locations along the organ, all signals were recorded simultaneously, and the electrical propagations were reconstructed. In the intact pregnant uterus at term, spikes propagated with high velocity in longitudinal (6.8 Ϯ 2.4 cm/s) and slower velocity in circular direction (2.8 Ϯ 1.0 cm/s; P Ͻ 0.01). Direction of propagation and frequency of activity were highly variable but showed similar patterns at the ovary or cervical end and along the anterior, posterior, and antimesometrial borders. Along mesometrium, spike propagation was sparse and fractionated. Migration of burst (0.6 Ϯ 0.4 cm/s) was significantly much slower than that of individual spikes (P Ͻ 0.001). Initial burst activity was located at variable locations along the ovarial end of the antimesometrial border, while the latest excitation occurred at the cervical end (1.2 Ϯ 0.9 min). In conclusion, high resolution electrical mapping of the intact pregnant uterus reveals fundamental properties in spatial and temporal patterns of spike and burst propagation that determine the contraction of the organ. spikes; myometrial burst migration ELECTRICAL ACTIVITY in the pregnant myometrium is characterized by phasic bursts of action potentials (spikes), which could be based on cyclic changes in transmembrane potential (24). Cyclic changes in potential resemble in some respects slow waves in the intestines and presumably propagate through the myometrium, similar to the propagation of the intestinal slow waves. In both cases, the depolarization induced by the (slow) waves initiate the opening of L-calcium channels leading to the occurrence of spikes. In the intestines, it is possible to record both slow waves and spikes with extracellular electrodes, and this made it possible to reconstruct the pattern of propagation of both signals and to study the complex interaction between these two electrical waveforms (22).In the myometrium, the basic electrical wave is too slow or its magnitude too small to be recorded extracellularly (9). The spikes, however, are visible in extracellular recordings and this led to several studies on their behavior. Miller et al. (25) analyzed spike propagation in pregnant uterine segments that were 3 ϫ 1 cm in size and showed that velocity in the longitudinal direction was much faster than in the circumferential direction. Lammers et al. (20) found similar results in equally small segments (8 ϫ 2 cm). Most of these studies were performed on isolated segments of...

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Section: Discussionmentioning

confidence: 99%

Patterns of electrical propagation in the intact pregnant guinea pig uterus

Lammers¹,

Mirghani²,

Stephen³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

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“…The uterus exhibits spontaneous contractile activity which, in both pregnant and nonpregnant females, is maintained relatively quiescent up to labor, at which time it markedly increases in strength, duration, and coordination to permit effective parturition (157,575). In several animal species, including humans, gap junctions and their constitutive connexins are sparsely represented among cells of prelabor myometrium (155)(156)(157)(158)528), a tissue which, at this time, also shows limited coupling, poor spatial propagation of action potentials, and asynchronous contractions (157,158). Gap junctions as well as electrical and metabolic coupling markedly increase, due to a differential modulation of different connexin isoforms between uterine muscle cells during labor and delivery (35, 155-158, 386, 447, 528).…”

Section: Muscular Contractionmentioning

confidence: 99%

Connexins: Key Mediators of Endocrine Function

Bosco

Haefliger

Meda

2011

Physiological Reviews

155

185

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The appearance of multicellular organisms imposed the development of several mechanisms for cell-to-cell communication, whereby different types of cells coordinate their function. Some of these mechanisms depend on the intercellular diffusion of signal molecules in the extracellular spaces, whereas others require cell-to-cell contact. Among the latter mechanisms, those provided by the proteins of the connexin family are widespread in most tissues. Connexin signaling is achieved via direct exchanges of cytosolic molecules between adjacent cells at gap junctions, for cell-to-cell coupling, and possibly also involves the formation of membrane “hemi-channels,” for the extracellular release of cytosolic signals, direct interactions between connexins and other cell proteins, and coordinated influence on the expression of multiple genes. Connexin signaling appears to be an obligatory attribute of all multicellular exocrine and endocrine glands. Specifically, the experimental evidence we review here points to a direct participation of the Cx36 isoform in the function of the insulin-producing β-cells of the endocrine pancreas, and of the Cx40 isoform in the function of the renin-producing juxtaglomerular epithelioid cells of the kidney cortex.

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“…1982;V crhocff and G ar field, 1986], Prostaglandins seem to directly influence the formation of gapjunctions in the rat [V crhocff and G ar field, 1986]. Prostaglandins may control the aggregation of the structural proteins of the gap junction by effecting cross-linking reactions or by changing the fluidity of the membrane [Garfield et al, 1980b].…”

Section: Discussionmentioning

confidence: 99%

Ultrastructure of the Porcine Myometrium during Pregnancy

Thilander

Rodríguez‐Martínez²

1989

Cells Tissues Organs

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The fine structure of myometrium from pigs collected at well-defined stages during pregnancy was investigated by transmission electron microscopy. The morphology of the pregnant myometrium resembled that in non-pregnant pigs. Thick myofilaments were conspicuous during early pregnancy, inapparent during mid-pregnancy and visible again by days 80–84 and towards parturition. Gap junctions were extremely rare throughout pregnancy. Only occasionally were nerve axons observed.

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Gap junction formation and regulation in myometrium

Cited by 113 publications

References 19 publications

Patterns of electrical propagation in the intact pregnant guinea pig uterus

Patterns of electrical propagation in the intact pregnant guinea pig uterus

Connexins: Key Mediators of Endocrine Function

Ultrastructure of the Porcine Myometrium during Pregnancy

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