Pericardial-esophageal Fistula Complicating Atrial Fibrillation Ablation Successfully Resolved after Pericardial Drainage with Conservative Management

A 40-year-old male patient underwent radiofrequency catheter ablation for symptomatic paroxysmal atrial fibrillation (AF). Although pulmonary vein (PV) isolation was successfully completed without acute complications, the patient began complaining of sustained retrosternal pain. Seventeen days after ablation, the patient visited the emergency room with fever and severe chest pain with pericarditis-like features. Chest computed tomography (CT) revealed clustered air bubbles in the pericardial space. Esophagography confirmed leakage of contrast agent into the pericardial space but not into the left atrium. While performing pericardiostomy, the operator confirmed the absence of active bleeding from the left atrium. Because there were no signs of left atrial-esophageal fistula, such as systemic embolization, conservative management based on strict fasting with fluids and antibiotic therapy was undertaken. Follow-up esophagography performed 2 weeks later showed no more contrast agent leakage, and the patient was discharged without further incident.

Optimization of the optical transparency of rodent tissues by modified PACT-based passive clearing

Recently, a bio-electrochemical technique known as CLARITY was reported for three-dimensional phenotype mapping within transparent tissues, allowing clearer whole-body and organ visualization with CB-perfusion (CUBIC) and leading to the development of whole-body clearing and transparency of intact tissues with the PACT (passive clarity technique) and PARS (perfusion-assisted agent release in situ) methodologies. We evaluated the structure–function relationships in circuits of the whole central nervous system (CNS) and various internal organs using improved methods with optimized passive clarity. Thus, in the present study, we aimed to improve the original PACT procedure and passive clearing protocols for different intact rodent tissues. We determined the optimal conditions for the passive clarity method that allowed the production of a transparent whole CNS by clearing the brain and spinal cord, as well as various organs. We also improved the tissue transparency using mPACT (modified PACT), a method for direct passive clearing, and whole perfusion-based PARS-mPACT, a method for fusion clearing, and we identified the appropriate experimental conditions. These optimized methods can be used for easy and economical high-resolution mapping and phenotyping of normal and pathological elements within intact tissues.

Comparison of Prolonged Atrial Electromechanical Delays with Different Definitions in the Discrimination of Patients with Non-Valvular Paroxysmal Atrial Fibrillation

BACKGROUND AND OBJECTIVES: Previous studies have evaluated atrial electromechanical delays (AEMDs) with a number of different definitions to discriminate patients with paroxysmal atrial fibrillation (PAF) from controls without PAF. However, their discriminative values for PAF have not previously been directly compared. SUBJECTS AND METHODS: A total of 65 PAF patients and 130 control subjects matched for age, sex, history of hypertension, and diabetes mellitus were selected. The AEMDi and AEMDp were defined as the time intervals from the initiation of the P wave on the surface electrocardiogram to the initiation and peak of the late diastolic transmitral inflow on pulsed wave Doppler images, respectively. The AEMDim and AEMDpm were defined as the time intervals from the initiation of the P wave on the surface electrocardiogram to the initiation and peak of the late diastolic lateral mitral annular motion on tissue Doppler images, respectively. RESULTS: There were no significant differences in the clinical characteristics between the two groups. All 4 AEMDs were consistently longer in the PAF group, and proven effective to differentiate the PAF patients from the controls. The AEMDi measurement had a larger area under the curve (AUC) than the other AEMDs, left atrial volume index, and P wave amplitude. However, the AEMDp, AEMDim, and AEMDpm measurements had AUCs similar to those of the left atrial volume index and P wave amplitude. CONCLUSION: The findings suggest that the AEMDi is better than the other AEMDs for the discrimination of PAF patients from the controls.

A Case of Pheochromocytoma Presenting as Ventricular Tachycardia Storm / 대한내과학회지

A 35-year-old woman was admitted for recurrent palpitations and headache with cold sweats. No structural abnormality was detected via cardiac imaging studies. A standard 12-lead electrocardiogram (ECG) revealed sustained monomorphic ventricular tachycardia (VT). Propranolol (120 mg/day) was administered; however, the frequency and duration of VT episodes increased rapidly. A 24-hr ambulatory ECG revealed frequent, successive, premature ventricular beats; accelerated idioventricular rhythms; and VTs with various cycle lengths and QRS complex morphologies. ECG findings suggested that the observed ventricular arrhythmias were driven by accelerated automaticity as their main electrophysiological mechanism. Based on clinical manifestations and ECG findings, pheochromocytoma was suspected. Solitary left adrenal pheochromocytoma was diagnosed by endocrine and imaging studies. Instead of propranolol, oral doxazosin (8 mg/day) was administered, and symptoms and VT attacks were successfully suppressed. After surgical resection of the pheochromocytoma, clinical VT was not observed in response to the high-dose isoproterenol provocation test.

Cardiac Arrest due to Recurrent Ventricular Fibrillation Triggered by Unifocal Ventricular Premature Complexes in a Silent Myocardial Infarction / 대한중환자의학회지

A 51-year-old male patient was referred for a sudden out-of-hospital cardiac arrest. Upon arrival, he was conscious and had no chest pain complaints. There was no abnormality in initial electrocardiographic and echocardiographic examinations. However, episodes of recurrent ventricular fibrillation (VF) were documented on rhythm monitoring. Each VF episode was triggered by an isolated monomorphic ventricular premature complex (VPC). Suspecting idiopathic VF, emergency radiofrequency catheter ablation was planned for the VPCs. However, when coronary angiography was performed to exclude silent ischemia, the results showed a total occlusion of the right coronary artery posterolateral branch, which is thought to supply the left ventricular inferior and septal wall. After successful reperfusion, VF episodes and the triggering VPCs disappeared. We are documenting this case to emphasize the potential for silent myocardial infarction to cause out-of-hospital sudden cardiac arrest even in a patient without any symptom or sign of acute coronary syndrome.

Cardiac Arrest due to Recurrent Ventricular Fibrillation Triggered by Unifocal Ventricular Premature Complexes in a Silent Myocardial Infarction / 대한구급학회지

A 51-year-old male patient was referred for a sudden out-of-hospital cardiac arrest. Upon arrival, he was conscious and had no chest pain complaints. There was no abnormality in initial electrocardiographic and echocardiographic examinations. However, episodes of recurrent ventricular fibrillation (VF) were documented on rhythm monitoring. Each VF episode was triggered by an isolated monomorphic ventricular premature complex (VPC). Suspecting idiopathic VF, emergency radiofrequency catheter ablation was planned for the VPCs. However, when coronary angiography was performed to exclude silent ischemia, the results showed a total occlusion of the right coronary artery posterolateral branch, which is thought to supply the left ventricular inferior and septal wall. After successful reperfusion, VF episodes and the triggering VPCs disappeared. We are documenting this case to emphasize the potential for silent myocardial infarction to cause out-of-hospital sudden cardiac arrest even in a patient without any symptom or sign of acute coronary syndrome.

Early Experience of Busan-Ulsan Regional Cardiocerebrovascular Center Project in the Treatment of ST Elevation Myocardial Infarction / 대한내과학회지

BACKGROUND/AIMS: The purpose of this study was to compare changes in primary percutaneous coronary artery intervention (PCI) outcomes after starting the government-directed Busan-Ulsan Regional Cardiocerebrovascular Center Project. METHODS: Patients with ST segment elevation myocardial infarction (STEMI) who visited the Busan-Ulsan Regional Cardiocerebrovascular Center from 1 June 2009 to 30 May 2011 were selected. Their medical records were retrospectively reviewed. Clinical and survival outcomes before and after starting the project were compared. RESULTS: A total of 122 patients (mean age, 63 +/- 13 years; male, 74%) with STEMI were selected for analysis. There were no significant differences in patients' baseline characteristics. After starting the Busan-Ulsan Regional Cardiocerebrovascular Center Project, the door-to-balloon time decreased from 72 +/- 30 to 59 +/- 22 minutes (p = 0.011). The door-to-balloon time when the PCI team did not stay in the hospital also decreased from 80 +/- 30 to 62 +/- 12 minutes (p = 0.005). However, there was no significant change in the total ischemic time (339 +/- 293 vs. 304 +/- 287 minutes, p = 0.514), survival discharge rate (94% vs. 93%, p = 1.000), or 1-year survival rate (89% vs. 91%, p = 0.996). CONCLUSIONS: After starting the government-directed Busan-Ulsan Regional Cardiocerebrovascular Center Project, the door-to-balloon time was significantly reduced. However, the total ischemic time and short-term survival remained unchanged.

Dose-Volume Analysis of Lung and Heart according to Respiration in Breast Cancer Patients Treated with Breast Conserving Surgery / 한국유방암학회지

PURPOSE: Adjuvant radiotherapy of breast cancer using a photon tangential field incurs a risk of late heart and lung toxicity. The use of free breathing (FB), expiration breath hold (EBH), and deep inspiration breath hold (DIBH) during tangential breast radiotherapy as a means of reducing irradiated lung and heart volume was evaluated. METHODS: In 10 women with left-sided breast cancer (mean age, 44 years) post-operative computed tomography (CT) scanning was done under different respiratory conditions using FB, EBH, and DIBH in 3 CT scans. For each scan, an optimized radiotherapy plan was designed with 6 MV photon tangential fields encompassing the clinical target volume after breast-conserving surgery. RESULTS: The results of dose-volume histograms were compared using three breathing pattern techniques for the irradiated volume and dose to the heart. A significant reduction dose to the irradiated heart volume for the DIBH breathing technique was compared to FB and EBH breathing techniques (p<0.05). CONCLUSION: This study demonstrated that the irradiated heart volume can be significantly reduced in patients with left-sided breast cancer using the DIBH breathing technique for tangential radiotherapy.

Comparison of Serum Procalcitonin with Ranson, APACHE-II, Glasgow and Balthazar CT Severity Index Scores in Predicting Severity of Acute Pancreatitis / 대한소화기학회지

BACKGROUND/AIMS: The aim of this study is to assess serum procalcitonin (PCT) for early prediction of severe acute pancreatitis compared with multiple scoring systems and biomarkers. METHODS: Forty-four patients with acute pancreatitis confirmed by radiological evidences, laboratory assessments, and clinical manifestation were prospectively enrolled. All blood samples and image studies were obtained within 24 hours of admission. RESULTS: Acute pancreatitis was graded as severe in 19 patients and mild in 25 patients according to the Atlanta criteria. Levels of serum PCT were significantly higher in severe acute pancreatitis (p=0.001). The accuracy of serum PCT as a predicting marker was 77.3%, which was similar to the acute physiology and chronic health examination (APACHE)-II score, worse than the Ranson score (93.2%) and better than the Balthazar CT index (65.9%). The most effective cut-off level of serum PCT was estimated at 1.77 ng/mL (AUC=0.797, 95% CI=0.658-0.935). In comparision to other simple biomarkers, serum PCT had more accurate value (77.3%) than C-reactive protein (68.2%), urea (75.0%) and lactic dehydrogenase (72.7%). Logistic regression analysis revealed that serum PCT has statistical significance in acute severe pancreatitis. Assessment of serum PCT levels and length of hospital stay by simple linear regression analysis revealed effective p-value with low R square level, which could make only possibilty for affection of serum PCT to admission duration (r2=0.127, p=0.021). CONCLUSIONS: Serum PCT was a promising simple biomarker and had similar accuracy of APACHE-II scores as predicting severity of acute pancreatitis.

Comparison of the Diagnostic Usefulness of Two Whole-Blood Interferon-Gamma Assays for Extrapulmonary Tuberculosis / 대한내과학회지

BACKGROUND/AIMS: The QuantiFERON-TB Gold (QFT-G) and QuantiFERON-TB Gold in tube (QFT-IT) assays have been studied primarily for the use of diagnosing active pulmonary tuberculosis (TB) or latent TB. The clinical usefulness of these assays for the detection of active extrapulmonary (EP) TB has not been fully defined. The aim of this study was to compare the diagnostic value of these two interferon-gamma assays for EP-TB. METHODS: From June 2007 to August 2010, we evaluated the usefulness of QFT-G (n = 56) and QFT-IT (n = 48) in patients (n = 104) with suspected EP-TB. The diagnostic sensitivity, specificity, postive predictive value (PPV), and negative predictive value (NPV) of QFT-G and QFT-IT, and the cut-off value of QFT-IT were analyzed. RESULTS: EP-TB was diagnosed in 55 (53%) patients. The overall sensitivity, specificity, PPV, and NPV of the QFT-IT assay were 96%, 42%, 62%, and 91%, respectively, and those of the QFT-G test were 81%, 52%, 68%, and 68%, respectively. In subgroup analyses according to infection site, the sensitivity and NPV of QFT-IT were higher than those of QFT-G. Analysis confirmed that the manufacturer's recommended test cut-off value fell within our cut-off value range (0.30-0.45 IU/mL; 95.8% sensitivity, 41.7% specificity). CONCLUSIONS: The QFT-IT assay showed superior sensitivity and NPV, and equivalent specificity, as comparison with the QFT-G test for the detection of Mycobacterium tuberculosis infection. The logistic benefits of the QFT-IT test format should facilitate the diagnosis of EP-TB.

Down-regulation of ATP-binding cassette transporter G1 expression by unmethylated CpG oligodeoxynucleotides in RAW 264.7 macrophages

We have investigated the effect of various forms of phosphodiester cytidine-phosphate-guanosine oligodeoxynucleotides (CpG ODNs) on the production of pro-inflammatory cytokines and related genes in RAW 264.7 macrophages. Treatment with the CpG ODNs increased the expression of tumor necrosis factor alpha (TNF-alpha), IL-6, and inducible nitric oxide synthase but not interleukin-1beta (IL-1beta). We also investigated the effect of CpG ODNs on the expression of ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1) genes which are known to facilitate cholesterol efflux from macrophages for anti-atherosclerosis. CpG 2006 significantly reduced the levels of ABCG1 mRNA as determined by real-time polymerase chain reaction, whereas ABCA1 mRNA level was not changed. Western blot analysis further confirmed the reduction of ABCG1 protein expression by CpG 2006. In addition, we also determined the protein level of peroxisome proliferator activated receptor gamma (PPARgamma), which is recognized as a transcriptional activator of ABC transporters, was also reduced by CpG 2006. Thus, these results suggest that ABCG1 is specifically down-regulated by CpG 2006 in a PPARgamma-dependent manner in macrophages.

Subclinical Myocardial Dysfunction in Metabolic Syndrome Patients without Hypertension

BACKGROUND: The aim of this study was to evaluate myocardial function in patients with non-hypertensive metabolic syndrome. METHODS: We selected metabolic syndrome patients (n = 42) without evidence of hypertension and compared them to age-matched control individuals (n = 20). All patients were evaluated by two-dimensional and tissue Doppler echocardiography including tissue Doppler derived strain and strain rate measurements. RESULTS: There were no significant differences between the two groups in mitral E and A inflow velocities or the E/A ratio. However, systolic and early diastolic myocardial velocities, and strain rate were significantly lower in patients with metabolic syndrome than in the control group (all p < 0.05). Multiple stepwise regression analyses revealed that age, waist circumference, and systolic blood pressure were independently associated with peak systolic myocardial velocity. CONCLUSION: These results indicate that metabolic syndrome patients without hypertension may have decrease of myocardial systolic and early diastolic velocities on tissue Doppler imaging, even if they appear to have normal systolic and diastolic function on conventional echocardiography.

Determination of Diastolic Dysfunction Cut-Off Value by Tissue Doppler Imaging in Adults 70 Years of Age or Older: A Comparative Analysis of Pulsed-Wave and Color-Coded Tissue Doppler Imaging

BACKGROUND AND OBJECTIVES: The cut-off value of diastolic dysfunction by tissue Doppler imaging (TDI) is affected by aging and modalities used (pulsed-wave vs. color-coded). The purpose of this study was to investigate the diastolic function of healthy elderly people and to determine the appropriate cut-off value of diastolic dysfunction in elderly individuals. SUBJECTS AND METHODS: Healthy volunteers (n=76) and patients with hypertension (n=51) aged > or =70 years underwent 2-dimensional and Doppler echocardiography. Mitral annulus velocities of TDI were measured at septal and lateral sites using the pulsed-wave and color-coded modalities. The appropriate cut-off value of diastolic dysfunction for healthy elderly individuals was defined as the lower limit of the 95% confidence interval for early diastolic mitral annulus velocity (Ea). RESULTS: The mean septal and lateral Ea were 6.5+/-1.5 and 8.3+/-1.7 cm/s, respectively, by pulsed-wave TDI, and 6.1+/-1.4 and 7.9+/-1.7 cm/s, respectively, by color-coded TDI. The cut-off values for diastolic dysfunction were as follows: septal and lateral Ea were 6.1 and 7.9 cm/s by pulsed-wave TDI, and 5.7 and 7.5 cm/s by color-coded TDI, respectively. When the group was stratified by gender, Ea was significantly lower in women than men. CONCLUSION: When interpreting diastolic function as measured by TDI in elderly subjects, different cut-off values should be considered based on the TDI modality, annulus site, and gender.

Effects of Continuous Repetitive Transcranial Magnetic Stimulation on Pain Response in Spinal Cord Injured Rat

OBJECTIVE: To investigate the effects of continuous repetitive transcranial magnetic stimulation (rTMS) on pain response in spinal cord injured rat. METHOD: Forty Sprague-Dawley rats (200~250 grams, female) were used. Thoracic spinal cord (T9) was contused using New York University (NYU) spinal cord impactor. Ten gram weight rod was dropped from a height of 25 mm to produce spinal cord contusion model with moderate injury. The animals were randomly assigned to two groups: one exposed to real magnetic stimulation (real-rTMS group) and the other not exposed to magnetic stimulation (sham-rTMS group). rTMS was applied for 8 weeks. To assess the effect of continuous rTMS on below-level pain responses after spinal cord injury (SCI), the hindpaw withdrawal response for thermal stimuli, cold stimuli and mechanical stimuli were compared between two groups. RESULTS: Behavioral response for pain showed that hindpaw withdrawal response for cold stimuli was reduced significantly from 4 weeks after SCI in real-rTMS group compared with sham group (p<0.05). CONCLUSION: These results suggest that continuous rTMS may have beneficial effects on attenuation of cold allodynia after SCI, and it might be an additional non-invasive therapeutic method in patients with chronic neuropathic pain after SCI.

Segmental Tissue Doppler Image-Derived Tei Index in Patients With Regional Wall Motion Abnormalities

BACKGROUND AND OBJECTIVES: Although the Tei index is a useful predictor of global ventricular function, it has not been investigated at the level of regional myocardial function. We therefore investigated the segmental tissue Doppler image derived-Tei index (TDI-Tei index) in patients with regional wall motion abnormalities. SUBJECTS AND METHODS: We prospectively studied 17 patients (mean age 62+/-9 years, 5 women) with left ventricular (LV) regional wall motion abnormalities. The Tei index, defined as the sum of isovolumetric contraction time (IVCT) and isovolumetric relaxation time (IVRT) divided by ejection time (ET), was measured in the basal and mid segments of the LV walls from standard apical views (4-, 2-, and 5-chamber views). We also obtained TDI velocity data in each segment. LV wall motion was classified as normal, hypokinetic, or akinetic, based on visual analysis. The TDI-Tei index, peak systolic myocardial velocity (Sm), early diastolic myocardial velocity (Em), and late diastolic myocardial velocity (Am) were analyzed in a total of 203 segments. RESULTS: Mean LV ejection fraction was 41.8+/-8.5%. TDI-Tei indices of dysfunctional segments (akinesis or hypokinesis, n=63) were significantly higher than those of normal segments (n=140) (0.714+/-0.169 vs. 0.669+/-0.135, p=0.041, respectively). Average values of TDI-Tei index, Sm, Em, and Am were 0.742+/-0.201, 4.206+/-1.336, 5.258+/-1.867, and 5.578+/-2.354 in akinetic segments; 0.677+/-0.101, 4.908+/-1.615, 5.369+/-2.121, and 5.542+/-2.492 in hypokinetic segments; and 0.669+/-0.135, 5.409+/-1.519, 6.108+/-2.356, and 6.719+/-2.466 in normal segments, respectively. A significant negative correlation was apparent between the TDI-Tei index and Sm (r=-0.302, p<0.001). CONCLUSION: These data suggest that the value of the segmental TDI-Tei index differs significantly according to regional function grade.

Post-Exposure Reporting of Needlestick and Sharp-Object Injuries among Nurses / 병원감염관리

BACKGROUND: Nurses are often exposed to needlestick and sharp-object injuries (NSIs). This study aimed to investigate the post-exposure reporting rate of NSIs among nurses. METHODS: The subjects were 84 nurses from 4 hospitals (3 hospitals with 300 or more beds and 1 hospital with less than 300 beds) who had experienced at least 1 NSI within a 6-month period. The instrument was a self-administered questionnaire, which was based on the EPINet report form and a questionnaire for NSIs among resident physicians, which was used by Choi et al. Data were collected between April 9 and June 15, 2009, and analyzed using descriptive statistics and the chi-square test, which was performed using SPSS with a significance level of 0.05. RESULTS: Among the 84 nurses who had experienced at least 1 NSI within 6 months, only 14.3% had reported the NSIs, and 58.4% of these subjects reported the NSI immediately after sustaining the injury. The most common reason for not reporting was "the patients were found out to be uninfectious" (81.9%) followed by "too busy" (65.3%). The incidence of post-exposure reporting was negatively related to the number of NSIs (chi-square=13.871, p<0.001) and positively related to assessments of infectivity of the patients (chi-square=4.248, P=0.039) and other persons' recommendations to report NSIs (chi-square=4.092, P=0.043). CONCLUSION: The post-exposure reporting rate was very low. The factors responsible for this low rate should be investigated in a more systematic manner, and more measures should be undertaken to increase the reporting rate among nurses.

A Case of Right Ventricular Dysfunction Caused by Pectus Excavatum

Pectus excavatum compresses the underlying right side of the heart, which might lead to right ventricular dysfunction as illustrated in this case report.

The Long-Lasting Pattern of the Neuropathic Radicular Pain in An Autologous Nucleus Pulposus Model of Rat

OBJECTIVE: To observe the long-lasting changes of pain progression with time course in an autologous nucleus pulposus model of rat. METHOD: The subjects were 25 Sprague-Dawley (Sprague- Dawley, 250 gm) male rats. They were randomly assigned into either the sham or experimental group. In the experimental group (n=15), autologous nucleus pulposus was harvested from the coccygeal intervertebral disc of the rat and this was grafted on the left L5 dorsal root ganglion. In the sham group (n=10), the left L4 and L5 nerve roots were exposed by laminectomy, but the nucleus pulposus was not grafted. All the rats were evaluated for mechanical allodynia and thermal hyperalgesia at 2 days before surgery, and on days 1, 5, 10, 20, 30, 40 and 50 after surgery. The morphological changes of the spinal nerves were assessed by toluidine blue staining on days 5 after surgery. RESULTS: In the ipsilateral hindpaw of the experimental group, there was a dramatic drop of the mechanical withdrawal threshold and the thermal withdrawal latency on day 1 after surgery, which was maintained at day 50 after surgery. In morphological study, pathological findings such as swelling of the myelin sheath, demyelination, swelling and degeneration of the axoplasm were observed in the spinal nerve at day 5 after surgery. CONCLUSION: The long-lasting pattern of neuropathic radicular pain shown in a rat model of lumbar disc herniations is helpful to understand the natural history of neuropathic radicular pain due to ruptured nucleus pulposus.

Effects of Functional Magnetic Stimulation on the Functional Recovery in a Rat Model of Spinal Cord Injury

OBJECTIVE: To investigate the effects of functional magnetic stimulation (FMS) on the functional recovery in a rat model of spinal cord injury (SCI). METHOD: Forty-five Sprague-Dawley rats (200~250 grams, female) were used. Rats were laminectomized and the T9 segment of spinal cord was contused using New York University (NYU) spinal impactor. Ten gram weight rod was dropped from a height of 25 mm to produce moderately contused spinal cord injury model. The animals were randomly assigned to 2 groups: one exposed to FMS (FMS group) and the other not exposed to FMS (non-FMS group). Transcranial functional magnetic stimulation was noninvasively applied for 4 weeks. To compare the results between FMS group and non-FMS group, motor functions were evaluated with the Basso, Beattie, and Bresnahan (BBB) locomtor rating scale and inclined plane test, and somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) were also recorded. RESULTS: There was a significant difference in locomotor recovery between FMS group and non-FMS group (p<0.05). Measurement of MEP was also indicated that amplitude of MEP in FMS group is larger than that in non-FMS group. CONCLUSION: These results indicate that FMS may have beneficial effects on motor recovery after spinal cord injury and the benefits of FMS could be an additional non-invasive therapeutic method for clinical trials in patients with spinal cord injury.

Single-Channel Recording of TASK-3-like K+ Channel and Up- Regulation of TASK-3 mRNA Expression after Spinal Cord Injury in Rat Dorsal Root Ganglion Neurons

Single-channel recordings of TASK-1 and TASK-3, members of two-pore domain K+ channel family, have not yet been reported in dorsal root ganglion (DRG) neurons, even though their mRNA and activity in whole-cell currents have been detected in these neurons. Here, we report single-channel kinetics of the TASK-3-like K+ channel in DRG neurons and up-regulation of TASK-3 mRNA expression in tissues isolated from animals with spinal cord injury (SCI). In DRG neurons, the single-channel conductance of TASK-3-like K+ channel was 33.0+/-0.1 pS at -60 mV, and TASK-3 activity fell by 65+/-5% when the extracellular pH was changed from 7.3 to 6.3, indicating that the DRG K+ channel is similar to cloned TASK-3 channel. TASK-3 mRNA and protein levels in brain, spinal cord, and DRG were significantly higher in injured animals than in sham-operated ones. These results indicate that TASK-3 channels are expressed and functional in DRG neurons and the expression level is up-regulated following SCI, and suggest that TASK-3 channel could act as a potential background K+ channel under SCI-induced acidic condition.