The contractility of the human uterus is under the fine control of a variety of interacting bioactive agents. During labour, the excitability of the uterus is drastically transformed in comparison with the non-labour state and is manifest at the membrane level via the acivity of uterine ion channels. This article reviews the contribution of potassium (K + ) channels to human uterine excitability.

BackgroundElevated pre-operative neutrophil: lymphocyte ratio (NLR) has been identified as a predictor of survival in patients with hepatocellular and colorectal cancer. The aim of this study was to examine the prognostic value of an elevated preoperative NLR following resection for oesophageal cancer.MethodsPatients who underwent resection for oesophageal carcinoma from June 1997 to September 2007 were identified from a local cancer database. Data on demographics, conventional prognostic markers, laboratory analyses including blood count results, and histopathology were collected and analysed.ResultsA total of 294 patients were identified with a median age at diagnosis of 65.2 (IQR 59-72) years. The median pre-operative time of blood sample collection was three days (IQR 1-8). The median neutrophil count was 64.2 × 10-9/litre, median lymphocyte count 23.9 × 10-9/litre, whilst the NLR was 2.69 (IQR 1.95-4.02). NLR did not prove to be a significant predictor of number of involved lymph nodes (Cox regression, p = 0.754), disease recurrence (p = 0.288) or death (Cox regression, p = 0.374). Furthermore, survival time was not significantly different between patients with high (≥ 3.5) or low (< 3.5) NLR (p = 0.49).ConclusionPreoperative NLR does not appear to offer useful predictive ability for outcome, disease-free and overall survival following oesophageal cancer resection.

Voltage gated potassium channels have been extensively studied in relation to cancer. In this review, we will focus on the role of two potassium channels, Ether à-go-go (Eag), Human ether à-go-go related gene (HERG), in cancer and their potential therapeutic utility in the treatment of cancer. Eag and HERG are expressed in cancers of various organs and have been implicated in cell cycle progression and proliferation of cancer cells. Inhibition of these channels has been shown to reduce proliferation both in vitro and vivo studies identifying potassium channel modulators as putative inhibitors of tumour progression. Eag channels in view of their restricted expression in normal tissue may emerge as novel tumour biomarkers.

Two populations, Ca2+-dependent (BKCa) and Ca2+-independent K+ (BK) channels of large conductance were identified in inside-out patches of nonlabor and labor freshly dispersed human pregnant myometrial cells, respectively. Cell-attached recordings from nonlabor myometrial cells frequently displayed BKCa channel openings characterized by a relatively low open-state probability, whereas similar recordings from labor tissue displayed either no channel openings or consistently high levels of channel activity that often exhibited clear, oscillatory activity. In inside-out patch recordings, Ba2+ (2–10 mM), 4-aminopyridine (0.1–1 mM), and Shaker B inactivating peptide (“ball peptide”) blocked the BKCa channel but were much less effective on BK channels. Application of tetraethylammonium to inside-out membrane patches reduced unitary current amplitude of BKCa and BK channels, with dissociation constants of 46 mM and 53 μM, respectively. Tetraethylammonium applied to outside-out patches decreased the unitary conductance of BKCa and BK channels, with dissociation constants of 423 and 395 μM, respectively. These results demonstrate that the properties of human myometrial large-conductance K+channels in myocytes isolated from laboring patients are significantly different from those isolated from nonlaboring patients.

No abstract

Large-conductance, calcium-dependent potassium (BKCa) channels are implicated in maintaining uterine quiescence during pregnancy. The mechanisms whereby calcium sensitivity of the BKCa channel is dramatically removed at parturition remain unknown. The aim of the present study was to investigate whether this loss of calcium sensitivity of the BKCa channel with the onset of labor is associated with changes in the protein expression of the alpha- and/or beta-subunit or arises from a physical dissociation of the alpha-subunit from the beta-subunit. The beta-subunit is a key determinant of BKCa-channel Ca2+ sensitivity. Western blot analysis, using alpha- and beta-subunit-specific antibodies, detected bands of 110-125 and 36 kDa, respectively. Protein expression levels of the alpha-subunit in term labor myometrium were significantly reduced compared with term pregnancy without labor. Furthermore, alpha-subunit levels at term pregnancy were significantly increased relative to the nonpregnant state, whereas levels at preterm gestations were unchanged. Densitometric analysis demonstrated significantly decreased beta-subunit levels in term and preterm labor samples compared with term nonlabor samples. Immunoprecipitation studies revealed the presence of both the alpha- and beta-subunits in samples taken before or after the onset of labor. We conclude that during labor, the alpha-subunit is not physically uncoupled from the beta-subunit, but a decline occurs in the level of beta-subunit protein, which may underlie the loss of calcium and voltage sensitivity of the BKCa channel with labor. Furthermore, reduced beta-subunit protein in preterm labor myometrium implies that ion channels may also contribute to pathophysiological labor.

BackgroundOvarian cancer is the second most common cancer of the female genital tract in the United Kingdom (UK), accounting for 6% of female deaths due to cancer. This cancer is associated with poor survival and there is a need for new treatments in addition to existing chemotherapy to improve survival. Potassium (K+) channels have been shown to be overexpressed in various cancers where they appear to play a role in cell proliferation and progression.ObjectivesTo determine the expression of the potassium channels Eag and HERG in ovarian cancer tissue and to assess their role in cell proliferation.MethodsThe expression of Eag and HERG potassium channels was examined in an ovarian cancer tissue microarray. Their role in cell proliferation was investigated by blocking voltage-gated potassium channels in an ovarian cancer cell line (SK-OV-3).ResultsWe show for the first time that high expression of Eag channels in ovarian cancer patients is significantly associated with poor survival (P = 0.016) unlike HERG channel expression where there was no correlation with survival. There was also a significant association of Eag staining with high tumour grade (P = 0.014) and presence of residual disease (P = 0.011). Proliferation of SK-OV-3 cells was significantly (P < 0.001) inhibited after treatment with voltage gated K+ channel blockers.ConclusionThis novel finding demonstrates a role for Eag as a prognostic marker for survival in patients with ovarian cancer.

No abstract