Predicting and analysing of the unfavourable outcomes of early applicated percutaneous endoscopic interlaminar discectomy for lumbar disc herniation: development and validation based nomogram.

OBJECTIVE: To predict and analyse the unfavourable outcomes of early applicated percutaneous endoscopic interlaminar discectomy for lumbar disc herniation. METHODS: Information of 426 patients treated by early applicated percutaneous endoscopic interlaminar discectomy (PEID) for lumbar disc herniation (LDH) at our hospital from June 2017 to October 2021 in addition to 17 other features was collected. The risk factors were selected by the least absolute shrinkage and selection operator method (LASSO) regression. Then, a prediction model (nomogram) was established to predict the unfavourable outcomes of using the risk factors selected from LASSO regression. Bootstrap (n = 1000) was used to perform the internal validation, and the performance of the model was assessed by the concordance index (C-index), receiver operating characteristic curve, and calibration curve. The decision curve analysis (DCA) and clinical impact curve (CIC) were used to assess the clinical utility of the model, respectively. RESULTS: Finally, 53 of 426 patients showed unfavourable outcomes. Five potential factors, Modic change, Calcification, Lumbar epidural steroid injection preoperative, Articular process hyperplasia and cohesion, and Laminoplasty technique, were selected according to the LASSO regression, that identified the predictors to establish nomogram model. Meanwhile, the C-index of the prediction nomogram was 0.847, the area under the receiver operating characteristic curve value was 0.847, and the interval bootstrapping (n = 1000) validation C-index was 0.809. The model has good practicability for clinics according to the DCA and CIC. CONCLUSION: This nomogram model has good predictive performance and clinical practicability, which could provide a certain basis for predicting unfavourable outcomes of early applicated PEID for LDH.

The role of prophylactic antibiotics in elective inguinal tension-free hernia repair: A systematic review and meta-analysis.

Whether to use antibiotics to prevent surgical site infection in elective inguinal tension-free hernia repair has been controversial. To systematically evaluate the effect of prophylactic antibiotic application in elective inguinal tension-free hernia repair, we identified all published randomised controlled trials of the effect of prophylactic antibiotic application on elective inguinal tension-free hernia repair were collected by computer retrieval from the China National Knowledge Infrastructure; VIP Database; Wanfang Database; China Biomedical Literature Database; and PubMed, EMBASE and Cochrane Library databases. Meta-analysis was performed by RevMan 5.3 software. The meta-analysis showed that the total incidence of surgical site infections [P = 0.003] and the incidence of superficial surgical site infections [P = 0.004] in the antibiotic group (AG) were lower than those in the non-antibiotic group (NAG). There was no significant difference in the total incidence of postoperative infections [P = 0.06], deep surgical site infections [P = 0.26] and seroma [P = 0.52] between the AG and the NAG. Based on current evidence, the application of prophylactic antibiotics in elective inguinal tension-free hernia repair can prevent the total incidence of surgical site infections and that of superficial surgical site infections but cannot prevent the total incidence of postoperative infection events, incidence of deep surgical site infections and incidence of seroma.

Piezo1 integration of vascular architecture with physiological force.

The mechanisms by which physical forces regulate endothelial cells to determine the complexities of vascular structure and function are enigmatic. Studies of sensory neurons have suggested Piezo proteins as subunits of Ca(2+)-permeable non-selective cationic channels for detection of noxious mechanical impact. Here we show Piezo1 (Fam38a) channels as sensors of frictional force (shear stress) and determinants of vascular structure in both development and adult physiology. Global or endothelial-specific disruption of mouse Piezo1 profoundly disturbed the developing vasculature and was embryonic lethal within days of the heart beating. Haploinsufficiency was not lethal but endothelial abnormality was detected in mature vessels. The importance of Piezo1 channels as sensors of blood flow was shown by Piezo1 dependence of shear-stress-evoked ionic current and calcium influx in endothelial cells and the ability of exogenous Piezo1 to confer sensitivity to shear stress on otherwise resistant cells. Downstream of this calcium influx there was protease activation and spatial reorganization of endothelial cells to the polarity of the applied force. The data suggest that Piezo1 channels function as pivotal integrators in vascular biology.

A propensity score-matched case-control comparative study of laparoscopic and open liver resection for hepatocellular carcinoma.

PURPOSE: Few results regarding the long-term survival from laparoscopic liver resection have been reported. The purpose of this study was to evaluate the long-term outcomes of laparoscopic liver resection for hepatocellular carcinoma. METHODS: IOf 638 patients who underwent open or laparoscopic liver resection for hepatocellular carcinoma, 184 treated by laparoscopic liver resection and 184 treated by open liver resection were studied using the propensity score matching method. The short-term surgical outcomes and long-term survival outcomes of these matched groups were compared. RESULTS: The two study groups were well matched with respect to age, sex, body mass index (BMI), liver function, underlying liver disease, American Society of Anesthesiologists (ASA) score, tumor location and type of resection. The laparoscopy group had a significantly longer operative time but significantly less intraoperative blood loss. Postoperatively, no significant intergroup differences were found for hospital stay, morbidity or mortality. The 5-year overall survival and disease-free survival were similar between the two groups. CONCLUSION: Laparoscopic liver resection for hepatocellular carcinoma is technically safe and feasible compared with open resection. The long-term outcomes of laparoscopic liver resection for hepatocellular carcinoma are considered acceptable.

Analysis of risk factors for recurrence of deep venous thrombosis in lower extremities.

BACKGROUND: Preventing relapse is a basic goal in the treatment of DVT and requires investigation of risk factors for recurrence of deep venous thrombosis (DVT) in the lower extremities. MATERIAL AND METHODS: We recruited and retrospectively reviewed 218 patients with recurrent DVT in the lower extremities diagnosed in our hospital from 2001 to 2012. RESULTS: Univariate analysis showed the incidence of recurrent DVT in patients with concomitant malignancy was 3 times higher than that in patients without malignancy (P<0.01); the incidence of recurrent DVT in patients with inferior vena cava filter (IVCF) at initial treatment was increased by 4.3 times as compared to patients treated with other modalities. In addition, pathological types of DVT (P=0.047), diabetes (P=0.040), nephrotic syndrome (NS; P=0.040), systemic lupus erythematosus (SLE; P=0.031) and poor compliance after discharge (P=0.030) were closely related to increased incidence of recurrent DVT. However, age (t=-1.927, P=0.055), gender (P=0.664), primary hypertension (P=0.098), embolectomy (P=0.367), and anti-coagulation (P=0.338) at initial treatment were not associated with recurrence of DVT. Multivariate analysis revealed that the risk for recurrent DVT in patients with concomitant malignancy was 3.5 times higher than that in patients without malignancy (OR=3.494, P<0.05); the risk for recurrent DVT in patients with IVCF at initial treatment was increased by 4.6 times as compared to patients treated with other modalities (OR=4.658, P<0.05). Pathological types of DVT, concomitant diabetes, NS, SLE and poor compliance after discharge were not associated with the risk for recurrent DVT (P>0.05). CONCLUSIONS: Concomitant malignancy and IVCF at initial treatment are independent risk factors for recurrent DVT in the lower extremities.

Levels of 91 circulating inflammatory proteins and risk of lumbar spine and pelvic fractures and peripheral ligament injuries: a two-sample mendelian randomization study.

OBJECTIVE: Lumbar spine and pelvic fractures(LPF) are combined with peripheral ligament injuries(PLI), frequently. It has been reported that the site of fracture injury is usually paralleled by the secretion of inflammatory proteins. This study aimed to investigate the causal relationship between 91 circulating inflammatory proteins and LPF and PLI by using a Two-sample Mendelian randomization (MR) analysis. METHODS: Single nucleotide polymorphisms (SNPs) associated with 91 circulating inflammatory proteins, as exposures were selected from a large genome-wide association study (GWAS). The genetic variant data for LPF and PLI as outcomes from the FinnGen consortium. The inverse-variance-weighted (IVW) method was utilized as the main analysis for exposures and outcomes. In addition, the final results were reinforced by the methods of MR Egger, weighted median, simple mode, and weighted mode. The sensitivity analyses were used to validate the robustness of results and ensure the absence of heterogeneity and horizontal pleiotropy. MR-Steiger was used to assess whether the causal direction was correct to avoid reverse causality. RESULTS: This study has shown that Beta-nerve growth factor(Beta-NGF) and Interferon gamma(IFN-gamma) are both involved in the occurrence of LPF and PLI, and they are reducing the risk of occurrence(OR:0.800, 95%CI: 0.650-0.983; OR:0.723, 95%CI:0.568-0.920 and OR:0.812, 95%CI:0.703-0.937; OR:0.828, 95%CI:0.700-0.980). Similarly, Axin-1 and Sulfotransferase 1A1 (SULT-1A1) were causally associated with LPF(OR:0.687, 95%CI:0.501-0.942 and OR:1.178,95%CI:1.010-1.373). Furthermore, Interleukin-4(IL-4), Macrophage inflammatory protein 1a(MIP-1a), and STAM binding protein(STAM-BP) were causally associated with PLI(OR:1.236, 95% CI: 1.058-1.443; OR:1.107, 95% CI: 1.008-1.214 and OR:0.759, 95% CI: 0.617-0.933). The influence of heterogeneity and horizontal pleiotropy were further excluded by sensitivity analysis. CONCLUSION: This study provides new insights into the relationship between circulating inflammatory proteins and LPF and PLI, and may provide new clues for predicting this risk.

Sirtuin 3 controls cardiac energetics and protects against oxidative stress in electromagnetic radiation-induced cardiomyopathy.

Electromagnetic radiation can cause injuries to both the structures and functions of the heart. No therapy is currently available to inhibit these untoward effects. Mitochondrial energetic damage and oxidative stress are drivers of electromagnetic radiation-induced cardiomyopathy (eRIC); however, the pathways that mediate these events are poorly defined. Sirtuin 3 (SIRT3) has been emerged as a key target for maintaining mitochondrial redox potential and metabolism, but its role in eRIC remains unknown. Here, Sirt3-KO mice and cardiac-specific SIRT3 transgenic mice were subjected to the investigation of eRIC. We found that Sirt3 protein expression level was down-regulated in eRIC mice model. Sirt3-KO markedly exaggerated decreases in cardiac energetics and increases in oxidative stress in microwave irradiation (MWI)-stressed mice. Conversely, cardiac-specific SIRT3 overexpression protected the hearts from these effects and rescued cardiac malfunction. Mechanistically, Sirt3 maintained AMP-activated protein kinase (AMPK) signaling pathway in MWI-stressed hearts in vivo. In conclusion, electromagnetic radiation repressed SIRT3 expression and disturbed cardiac energetics and redox homeostasis. The increased SIRT3 expression and AMPK activation in vivo prevented eRIC, indicating that SIRT3 will be a potential therapeutic target for curative interventions in eRIC.

A fighter pilot case of pulmonary sequestration.

BACKGROUND: Pulmonary sequestration is a rare congenital malformation. The diagnosis of pulmonary sequestration is based on the identification of an abnormal arterial supply. Conventional treatment for pulmonary sequestration is surgical removal of the tissue, which may induce serious trauma and requires a long recovery time. Recently, endovascular treatment has become feasible as a safer and less invasive method to treat pulmonary sequestration. CASE REPORT: To the best of our knowledge, pulmonary sequestration has not been reported in pilots. In this study, we report a fighter pilot case of intralobar pulmonary sequestration detected with the assistance of spiral computed tomography (CT) and digital subtraction angiography. The young fighter pilot had experienced recurrent hemoptysis and pulmonary infections for approximately 10 yr before the pulmonary sequestration was diagnosed. We performed a transcatheter arterial embolization and a subsequent CT angiography confirmed complete infarction of the sequestration. After the treatment, no clinical complications were observed and the patient, with normal lung function restored, was qualified to serve as a fighter pilot again. DISCUSSION: Compared with conventional removal surgery, endovascular treatment is a superior treatment for pulmonary sequestration in a fighter pilot in maintenance of pilot qualification.

Meta-Analysis on the Efficacy and Safety of Laparoscopic Surgery for Large Gastric Gastrointestinal Stromal Tumors.

BACKGROUND: The aim of this study was to conduct a meta-analysis comparing the safety and feasibility of laparoscopic versus open resection for gastric gastrointestinal stromal tumors (GISTs) larger than 5 cm. METHOD: We searched the Cochrane Library, PubMed, and Embase for relevant articles. Randomized and nonrandomized clinical trials were identified and included in this study. Searching for related articles on large GIST (>5 cm) for laparoscopic resection (laparoscopic group [LAPG]) and open resection (open group [OG]), RevMan 5.3 was used for data analysis, comparing 2 groups of operation time, intraoperative blood loss, complications, length of hospital stay, recurrence rate, disease-free survival, and overall survival. RESULTS: Seven studies including 440 patients were identified for the meta-analysis. Meta-analysis revealed that LAPG had less bleeding, shorter postoperative hospital stay, and a better 5-year disease-free survival. There was no significant difference between LAPG and OG in operation time, postoperative complications, recurrence rate, and overall survival. CONCLUSION: Laparoscopic resection of large (>5 cm) GIST is safe and feasible and has the advantages of less intraoperative blood loss and fast postoperative recovery, with a good outcome in the recent oncology.

Cerebral hemodynamics and brain functional activity during lower body negative pressure.

INTRODUCTION: Exposure to high +Gz acceleration forces on a centrifuge or in an aircraft can severely decrease cerebral blood perfusion and cause rapid G-induced loss of consciousness. However, milder acceleration may gradually reduce cerebral blood flow and affect cognitive function in subtler ways. This study used lower body negative pressure (LBNP) to mimic +Gz circulatory effects in order to study cerebral hemodynamics and brain function. METHODS: Subjects were 15 healthy men, 19-21 yr of age. They were exposed to LBNP at two levels for 5 min each separated by a 10-min recovery period. The conditions were low (LO), -4.00 kPa (-30 mmHg) and high (HI), -6.67 kPa (-50 mmHg).Variables measured before, during, and after LBNP included cerebral blood flow velocity (CBFV) in the middle cerebral artery, blood oxygen saturation (SaO2), heart rate (HR), blood pressure, P300 of event-related EEG potentials, reaction time, and tracking error. RESULTS: LO significantly reduced CBFV at 4 and 5 min, increased HR, and decreased the amplitude of P300, but none of the other variables changed from baseline. In contrast, HI produced significant changes in most variables: CBFV decreased at 2 min and then fell further at 4 and 5 min, HR increased, and SaO2 decreased. Significant neurocognitive changes included increased latency and reduced amplitude of P300, slower reaction time, and greater tracking error. CONCLUSION: The higher level of LBNP used here reduced cerebral perfusion sufficiently to impair neurocognitive function. This model may be useful for further studies of these and other variables under closely controlled conditions.

[Changes in voltage-dependent calcium channel currents of vascular smooth muscle cells isolated from small mesenteric arteries of simulated weightless rats].

The aim of the present study was to examine the changes in the function of voltage-dependent calcium channels (VDC) of vascular smooth muscle cells (VSMCs) isolated from small mesenteric arteries of rats subjected to 1-week or 4-week simulated weightlessness. The whole-cell recording mode was used to record current densities and Ba(2+) was used as charge carrier. Curves and fitting parameters describing steady-state activation and inactivation characteristics of VDC were thus obtained. The inward currents recorded from the VSMCs of small mesenteric arteries were mainly the Ba(2+) currents through the long-lasting type VDC (L-VDC). Compared with that of the control rats, the L-VDC current density of VSMCs from small mesenteric arteries showed a trend toward a decrease in the rats after 1-week , while a significant decrease was observed in the rats after 4-week simulated weightlessness. However, there were no significant differences in the opening and closing rates of L-VDCs, the position of steady-state activation and inactivation curves, and in the parameters, V(0.5) and k, between either of the two groups and its respective control group. The membrane capacitance and the reversal potential of the VSMCs from the small mesenteric arteries of rats after simulated weightlessness also showed no significant changes. These findings suggest that the decreased function of the L-VDC in hindquarter VSMCs might be one of the electrophysiological mechanisms that mediate the depressed vasoreactivity and atrophic change in hindquarter arteries during adaptation to simulated weightlessness in rats.

Vascular endothelial growth factor expression and pathological changes in the local tissue of facial hemangiomas following injections with pure alcohol.

The aim of the present study was to investigate the association between the formation of hemangioma and the expression of vascular endothelial growth factor (VEGF) following local injections of pure alcohol in patients exhibiting hemangioma. Ten healthy subjects (control group) and 10 hemangioma patients (treatment group) were included in the study population, with the hemangioma patients receiving one injection of pure alcohol. The VEGF levels were evaluated in the treatment and control group subjects prior to and following the injection using enzyme-linked immunosorbent assay; furthermore, local tissue was excised to perform pathological analysis one week after the injections. The VEGF levels of the healthy group were identified to be significantly lower when compared with those of the treatment group prior to the injections (P<0.01) and one week after the injections (P<0.01), however, were not significantly different when compared with the treatment group one month after the injections (P>0.01). Therefore, serum VEGF concentrations in the peripheral blood may be a clinical indicator of the efficacy of clinical treatment and aid with determination of the prognosis.

[Changes in potassium currents of vascular smooth muscle cells isolated from hindquarter arteries of rats after 4 weeks simulated weightlessness].

The changes in potassium currents of vascular smooth muscle cells (VSMCs) isolated from saphenous arteries and the 2nd-6th order branches of the mesenteric arteries of 4-week tail-suspended rats (SUS) were examined using whole cell patch clamp technique. The resting potential (RP) of the VSMCs from SUS group was more negative compared with that of the control group (CON).The whole cell potassium current densities of VSMCs isolated from the saphenous arteries and small mesenteric arteries in SUS group were significantly larger than those of the CON group.The BK(Ca) and K(V) current densities of VSMCs from saphenous arteries and small mesenteric arteries from SUS group were also significantly larger than those from the CON group.It is speculated that the hyperpolarization of VSMCs and decreased calcium influx through voltage-dependent calcium channels might be one of the electrophysiological mechanisms involved in the depressed vasoreactivity of hindquarter arteries induced by simulated weightlessness.

[Changes of potassium channel activity of hindlimb arterial smooth muscle cells in tail-suspended rats].

OBJECTIVE: To examine the change of potassium channel function in hindlimb arterial smooth muscle cells in tail-suspended rats and to elucidate the underlying electro-physiological mechanisms responsible for the depressed vascular responsiveness of hindlimb arteries induced by simulated weightlessness. METHOD: The contractile responsiveness of femoral arterial rings of 1-wk and 4-wk tail-suspended rats to potassium channel blockers, tetraethylammonium chloride (TEA) and 4-aminopyridine (4-AP), were recorded, and the currents of large conductance calcium-dependent potassium channel (BK(Ca)) and voltage activated potassium channel (Kv) of vascular smooth muscle cells (VSMCs) in saphenous arteries from 1-wk tail-suspended rats were recorded using the whole cell recording mode of patch clamp technique. RESULT: The femoral arteries from of 1-wk and 4-wk tail-suspended rats showed a decreased contractile response to 60 mM KCl, and the ratio of their contractile responses induced by TEA or 4-AP to their responses induced by 60 mM KCl increased significantly after 1-wk and 4-wk simulated weightlessness. However no difference was found between 1-wk and 4-wk tail-suspended rats. The whole cell current recording showed that BK(Ca) current densities and K(v) current densities of VSMCs in saphenous artery increased significantly after 1-wk simulated weightlessness. CONCLUSION: The contractile response of hindlimb arteries to KCl decreased after simulated weightlessness. The activities of BK(Ca) and K(v) of smooth muscle cells in hindlimb arteries from tail-suspended rats increased, and these changes might be among the electro-physiological mechanisms involved in the depressed vasoreactivity of hindlimb arteries due to simulated weightlessness.

[Characteristics and aeromedical evaluation of Meniere's disease in flight aircrew].

OBJECTIVE: To find out the clinical characteristics of Meniere's disease in flight aircrew and discuss relevant principles of clinical aviation medicine, in order to summarize experience in medical evaluation of aircrew. METHOD: Collect the data of 35 cases that were diagnosed with Meniere's disease from 1966 to 2011 in our hospital and analyze the clinical characteristics, diagnosis and flight conclusion of them. RESULT: Among the 35 cases, 34 patients complained of vertigo. 27 patients complained of tinnitus and 21 patients complained of hearing loss. (1) 18 cases manifested typical symptoms of Meniere's disease (paroxysmal vertigo, fluctuating neurosensory hearing loss, tinnitus and ear fullness); (2) 7 patients showed the symptoms of vertigo and tinnitus, not complaining of significant hearing loss (after inspection. 4 of them proved the low-frequency hearing loss); (3) 7 patients only manifested as vertigo; (4) 2 patients manifested as tinnitus and hearing loss. 1 patients manifested only hearing loss. On the basis of the diagnostic criteria of Meniere's disease formulated hy Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery. 22 patients were diagnosed with definite Meniere's disease, 2 patients were diagnosed with probable Meniere's disease, 11 patients were diagnosed with possible Meniere's disease. For patients with definite Meniere's disease and probable Meniere's disease, the phases of the disease were: 11 cases of phase I, 7 case of phase II and 6 case of phase III. The flight conclusion of all the 35 patients was permanent grounding. The time from the attack of the disease to receiving the conclusion of permanent grounding fluctuated from three months to 11 years. CONCLUSION: The diagnosis of Meniere's disease of flight aircrew must he cautious. For patients with atypical symptoms of Meniere's disease, the diagnosis should be made in the case of completely ruling out other possible diseases. Once be diagnosed, a patient should normally be flight unqualified. The flying waiver would he recommended only under exceptional circumstances. The criterion of waiver condition need to be further explored in the future.

Activation of the Cl- channel ANO1 by localized calcium signals in nociceptive sensory neurons requires coupling with the IP3 receptor.

We report that anoctamin 1 (ANO1; also known as TMEM16A) Ca(2+)-activated Cl(-) channels in small neurons from dorsal root ganglia are preferentially activated by particular pools of intracellular Ca(2+). These ANO1 channels can be selectively activated by the G protein-coupled receptor (GPCR)-induced release of Ca(2+) from intracellular stores but not by Ca(2+) influx through voltage-gated Ca(2+) channels. This ability to discriminate between Ca(2+) pools was achieved by the tethering of ANO1-containing plasma membrane domains, which also contained GPCRs such as bradykinin receptor 2 and protease-activated receptor 2, to juxtamembrane regions of the endoplasmic reticulum. Interaction of the carboxyl terminus and the first intracellular loop of ANO1 with IP3R1 (inositol 1,4,5-trisphosphate receptor 1) contributed to the tethering. Disruption of membrane microdomains blocked the ANO1 and IP3R1 interaction and resulted in the loss of coupling between GPCR signaling and ANO1. The junctional signaling complex enabled ANO1-mediated excitation in response to specific Ca(2+)signals rather than to global changes in intracellular Ca(2+).

As2O3 may be a treatment option for adenoid cystic carcinoma of salivary gland.

Adenoid cystic carcinoma (ACC) is an uncommon tumor of the head and neck that may occur in any salivary gland tissue. Discouraging treatment outcomes may be related to perineural spread, loco regional invasion, and an unusually high incidence of metastatic potential. It presents a number of challenges related to facial nerve management and disease extension into surrounding soft tissue and bony compartments. ACC mostly occurring in the major and minor salivary glands, has some unique characteristics such as slow growth, diffuse invasion, and high incidence of distant metastasis. It is a high malignant carcinoma characterized by intensive local invasion and insidious distant metastasis to the lung at an early stage, which is responsible for a poor long-term survival rate. The main clinical treatment to adenoid cystic carcinoma depended on surgical operation in the past. However, it was not so easy to completely excise adenoid cystic carcinoma which resulting in the residual of tumor cells. Therefore, radiotherapy was often used after the operation. Radiotherapy alone cannot achieve the goal of radical cure, but operation combined with radiotherapy can evidently reduce the post-operative recurrence rate and increase the survival rate. Adenoid cystic carcinoma is not sensitive to conventional chemotherapeutics, so it is necessary to explore a new kind of drug which possesses inhibition and killing effects to this tumor. Arsenic trioxide (A(S2)O(3), ATO), a trivalent inorganic arsenite, has been proved to be an effective therapeutic agent against acute promyelocytic leukemia. Numerous reports have revealed that arsenite exerts its therapeutic activity by induction of apoptosis. It also induces apoptosis in a variety of cancer cells over a wide dose range. A(S2)O(3) may become a treatment option for adenoid cystic carcinoma of salivary gland.

[Effect of vasonatrin peptide on the Ca2+ activated K+ channels of vascular smooth muscle cells isolated from rat mesentery arteries].

AIM: To investigate effect and mechanism of vasonatrin peptide (VNP) on Ca2+ activated K+ channels (K(Ca)) of vascular smooth muscle cells (VSMCs) isolated from rat mesentery arteries. METHODS: Changes of K(Ca) induced by VNP were measured by the means of whole cell recording mode of patch clamp, furthermore effects of HS-142-1(0.3 g/L), 8-Br-cGMP and methylene blue (MB) were observed. RESULTS: K(Ca) was significantly enhanced by VNP (10(-6) mol/L), which was mimicked by 8-Br-cGMP(10(-3) mol/L) and blocked completely by HS-142-1 or MB (2 x 10(-5) mol/L). CONCLUSION: VNP increases K(Ca) of VSMCs isolated from rat mesenteric arteries, by binding with natriuretic peptide guanylate cyclase-coupled receptors and increasing the intracellular level of cGMP in VSMCs.

Changes in potassium currents of vascular smooth muscle cells from hindquarter arteries of 4-wk simulated weightlessness rats.

It has been reported by Delp et al and Ma J et al that the vasoreactivity of hindquarter vessels from simulated weightless rats decreased. Many factors may contribute to the depressed vasoreactivity. Because the potassium channels play an important role in regulating the resting potential and contribute to the action of some vasoactive substances, we speculated that the changes of potassium channels may be an electro-physiological mechanism involved in the depressed vasoreactivity of hindquarter vessels due to simulated weightlessness.

Differential activation of potassium channels in cerebral and hindquarter arteries of rats during simulated microgravity.

The purpose of this study was to test the hypothesis that differential autoregulation of cerebral and hindquarter arteries during simulated microgravity is mediated or modulated by differential activation of K(+) channels in vascular smooth muscle cells (VSMCs) of arteries in different anatomic regions. Sprague-Dawley rats were subjected to 1- and 4-wk tail suspension to simulate the cardiovascular deconditioning effect due to short- and medium-term microgravity. K(+) channel function of VSMCs was studied by pharmacological methods and patch-clamp techniques. Large-conductance Ca(2+)-activated K(+) (BK(Ca)) and voltage-gated K(+) (K(v)) currents were determined by subtracting the current recorded after applications of 1 mM tetraethylammonium (TEA) and 1 mM TEA + 3 mM 4-aminopyridine (4-AP), respectively, from that of before. For cerebral vessels, the normalized contractility of basilar arterial rings to TEA, a BK(Ca) blocker, and 4-AP, a K(v) blocker, was significantly decreased after 1- and 4-wk simulated microgravity, respectively. VSMCs isolated from the middle cerebral artery branches of suspended rats had a more depolarized membrane potential (E(m)) and a smaller K(+) current density compared with those of control rats. Furthermore, the reduced total current density was due to smaller BK(Ca) and smaller K(v) current density in cerebral VSMCs after 1- and 4-wk tail suspension, respectively. For hindquarter vessels, VSMCs isolated from second- to sixth-order small mesenteric arteries of both 1- and 4-wk suspended rats had a more negative E(m) and larger K(+) current densities for total, BK(Ca), and K(v) currents. These results indicate that differential activation of K(+) channels occur in cerebral and hindquarter VSMCs during short- and medium-term simulated microgravity. It is further suggested that different profiles of channel remodeling might occur in VSMCs as one of the important underlying cellular mechanisms to mediate and modulate differential vascular adaptation during microgravity.