Isolation and Functional Determination of SKOR Potassium Channel in Purple Osier Willow, Salix purpurea

Potassium (K+) plays key roles in plant growth and development. However, molecular mechanism studies of K+ nutrition in forest plants are largely rare. In plants, SKOR gene encodes for the outward rectifying Shaker-type K+ channel that is responsible for the long-distance transportation of K+ through xylem in roots. In this study, we determined a Shaker-type K+ channel gene in purple osier (Salix purpurea), designated as SpuSKOR, and determined its function using a patch clamp electrophysiological system. SpuSKOR was closely clustered with poplar PtrSKOR in the phylogenetic tree. Quantitative real-time PCR (qRT-PCR) analyses demonstrated that SpuSKOR was predominantly expressed in roots, and expression decreased under K+ depletion conditions. Patch clamp analysis via HEK293-T cells demonstrated that the activity of the SpuSKOR channel was activated when the cell membrane voltage reached at -10 mV, and the channel activity was enhanced along with the increase of membrane voltage. Outward currents were recorded and induced in response to the decrease of external K+ concentration. Our results indicate that SpuSKOR is a typical voltage dependent outwardly rectifying K+ channel in purple osier. This study provides theoretical basis for revealing the mechanism of K+ transport and distribution in woody plants.

P wave dispersion – fading light of a popular parameter

Background The P wave dispersion concept was created to describe the non-uniform atrial conduction as a separate AF factor. However the major assumptions of the theory are inconsistent with the main principle of electrocardiography, which assumes that 12 leads of ECG, recorded simultaneously, register the same events at the same time. The presence of dispersion suggests the presence of a P wave in one lead, while in the other one it has ended and no longer exists. This observation per se could be considered as a methodological artifact. Objective The major objective is to present that the P wave dispersion descends from imprecise measurements in various ECG leads. We intend to demonstrate that more accurate measurements make this parameter disappear. Methods Our study included 150 patients (89F, 61M) assessed using the electrophysiological system, which allowed to assess the sinus P waves. The P wave duration was measured by 3 independent researchers in all leads twice: 1. paper speed=50 mm/s, enhancement 16x (basic measurement) 2. paper speed=200 mm/s, enhancement 128–256x, simultaneously measuring the P wave dispersion. All measurements were repeated 3 times. Results The results are presented in Table 1 Conclusion 1. The P wave dispersion is the artifact of measurement. It is clear that after using much more accurate tools, the parameter disappears. 2. The P-wave dispersion is connected with Pmax, therefore may be apparently clinically useful but as a matter of fact, doesn't carry any meaning itself. 3.The significant P wave duration parameter should be a total atrial activation time, from the beginning of the earliest recorded P wave, till the end of the last Pwave recorded in any lead. Funding Acknowledgement Type of funding source: None

P5696The first results from multicentre study of noninvasive epi-endocardial panoramic mapping of ventricular arrhythmias

Background A noninvasive epi-endocardial panoramic mapping is a promising ECG Imaging technology alternative to catheter-based invasive methods. Some unstable ventricular arrhythmias arising from complex anatomic sites render mapping and ablation difficulties with conventional approach. Objective To assess the use of a noninvasive panoramic mapping for diagnosis and localization of ventricular arrhythmias. Methods 35 patients (20 male, median (25–75%) age – 35 (12–60) years) with polymorphic premature ventricular contractions (PVCs) and 3–5 different QRS morphologies (1500–19000 per day) or monomorphic ventricular tachycardia (VT) were enrolled in the study. Up to 224 body surface electrodes were connected to the noninvasive epi-endocardial electrophysiological system for multichannel ECG recording followed by computed tomography of the heart and torso. The body-surface ECG data were processed using inverse-problem solution software in combination with realistic 3D anatomical models of the heart and torso. The earliest site of activation were determined on isopotential maps for each QRS morphology. On the same day patients underwent catheter ablation of one or two dominant PVC morphologies using 3D electroanatomical mapping system. The site of successful catheter ablation served as final confirmation. Afterwards, electroanatomical maps were exported from Carto 3 system and compared with noninvasive maps using custom written Python-based software. Results In total 47 similar PVC morphologies in 30 patients were mapped using noninvasive and invasive electroanatomical mapping systems, 34 (72%) PVCs were correctly diagnosed and 13 (28%) did not accurately correspond with sites of radiofrequency ablation. In 2 patients with four PVC morphologies an early activation zones were determined as a breakthrough from epi and endocardial surface using noninvasive activation maps. Conclusion Non invasive epi-endocardial panoramic mapping technology is a novel diagnostic method which can be used as an additional pre-procedural tool for topical diagnosis of polymorphic PVCs.

Single Cell Electrophysiological Analysis via Sub-Micrometer Openings

Single cell electrophysiological analyses were demonstrated via sub-micrometer openings using micro-and nano-machining technologies. In the prototype demonstration, a 6GΩ seal resistance was achieved on a HeLa cell, a cervical cancer cell line with size between 10~20μm, using the microfabricated electrophysiological system with opening size of 500nm in diameter and the measured electrolyte pipette resistance is 200kΩ. In a second experiment on a vacuolar yeast cell of 3~5μm in size, using a device with 800nm opening, a 500MΩ seal resistance was achieved and the measured electrolyte pipette resistance is 1MΩ.