Plasma membrane receptor mediated MAPK signaling pathways are activated in human uterine cervix at parturition

BACKGROUND: Cervical ripening resembles an inflammatory reaction. Estrogens induce leukocyte migration into tissue and factors promoting cervical remodeling and labor, although the mechanisms are only partially known. The aim of this study was to investigate whether plasma membrane receptor mediated pathways, known to be activated by estrogens and proinflammatory compounds, are involved in cervical ripening before labor. METHODS: The expression and distribution of mitogen activated protein kinases (MAPK), which transduce extracellular signals into intracellular responses through phosphorylation, and their intracellular targets transcription factors c-Jun and c-Fos proteins (AP-1) were analysed in cervical biopsies from term pregnant women (TP), immediately after parturition (PP), and from non-pregnant women (NP). Immunohistochemistry and RT-PCR techniques were used. RESULTS: Cell-specific alterations in the immunostaining pattern for MAPK were observed. The expressions of activated, phosphorylated MAPK forms pERK1/2, pJNK and p38MAPK were significantly increased in cervical stroma until TP and pERK1/2 expression was significantly enhanced in PP group. c-Jun was significantly increased in cervical stroma and smooth muscle in TP as compared to NP group. c-Fos was significantly increased in stroma, squamous epithelium and glandular epithelium in PP as compared to TP group. CONCLUSION: We report, for the first time, cell-specific activation of pMAPKs and their targets transcription factors c-Fos and c-Jun (AP-1) proteins in human uterine cervix until term pregnancy, and immediately after parturition. These results suggest a role for MAPK activation in cervical ripening before labor

The effects of sodium on calcium mobilization in vascular smooth muscle cells

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN026604 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Ca2+ stores in smooth muscle cells: Ca2+ buffering and coupling to AVP-evoked inositol phosphate synthesis

Cytosolic Ca2+ concentrations ([Ca2+]cyt) and [3H]inositol phosphates ([3H]InsP) were correlated while decreasing the Ca2+ content of sarcoplasmic reticulum (SR) stores in cultured A7r5 cells at rest and after activation with 8-arginine vasopressin (AVP). Decreasing Ca2+ influx by reducing extracellular Ca2+ or by treatment with verapamil had no effect on resting [Ca2+]cyt but significantly inhibited the AVP-evoked Ca2+ transients (delta Ca2+). Neither treatment affected basal [3H]InsP, but both treatments increased AVP-evoked synthesis of [3H]InsP. Likewise, basal [3H]InsP were unaffected by brief (10-30 s) exposures to thapsigargin (TG), while AVP-induced [3H]InsP synthesis was significantly augmented. Similar treatment with TG rapidly increased resting [Ca2+]cyt and decreased SR Ca2+ by 9-25% as manifested by decreased delta Ca2+. By contrast, ryanodine induced slow increases in [Ca2+]cyt that stabilized within 30 min; subsequent AVP-induced delta Ca2+ were attenuated by 50%. Ryanodine had no effect on either basal or stimulated [3H]InsP levels. Agents that elevate adenosine 3',5'-cyclic monophosphate (cAMP) such as caffeine, 8-bromo-cAMP, and forskolin inhibited AVP-evoked [3H]InsP formation. These observations provide further characterization of a communication pathway between the AVP-sensitive Ca2+ stores in the SR and the plasmalemmal enzyme system involved in the synthesis of inositol 1,4,5-trisphosphate. This pathway is manifested by an inverse relationship between the Ca2+ content of an AVP-sensitive, ryanodine-insensitive SR Ca2+ store and evoked [3H]InsP synthesis and may represent an important component in the tonic regulation of resting [Ca2+]cyt and vasoconstrictor- and hormone-evoked SR Ca2+ release

The responsiveness of isolated human hand vein endothelial cells in normal pregnancy and in pre-eclampsia

Human hand vein endothelial cells were isolated from blood obtained by traumatic venepuncture. Cells were identified as endothelial by staining with endothelium-specific antibodies. The subject groups studied were (i) non-pregnant, (ii) pregnant (mean, 35 weeks gestation) and (iii) pre-eclamptic women (mean, 36 weeks gestation).Fura-2 was used to measure agonist-induced responses in intracellular Ca2+ in single endothelial cells isolated and maintained in vitro. All of the cells examined responded to adenosine triphosphate (ATP) with a large transient increase in Ca2+ followed by a sustained plateau.The responses to ATP were significantly larger in the cells from pregnant women than in those from non-pregnant and pre-eclamptic women, but no other differences were observed. The amplitudes of the responses to ATP were (means ± s.e.m.) 0.56 ± 0.04, 1.42 ± 0.24 and 0.65 ± 0.09 fura-2 ratio units for cells from non-pregnant, pregnant and pre-eclamptic subjects, respectively.In cells isolated from non-pregnant subjects, the amplitude of the responses to carbachol, histamine and bradykinin were all smaller than those activated by ATP: 5.1, 13.9 and 4.4%, respectively. Not all cells responded to these agonists: 25% responded to carbachol, 70.5% responded to histamine and 12.5% responded to bradykinin. Sixty-five per cent of the cells from normotensive pregnant subjects responded to bradykinin compared with 25% in the non-pregnant and 13.9% in the pre-eclamptic subjects.These data suggest that there may be differences in the responsiveness of venous endothelial cells in pregnancy and that pre-eclamptic cells behave differently