Phosphorylation states greatly regulate the activity and gating properties of Cav 3.1 T-type Ca2+ channels.

Cav 3.1 T-type Ca2+ channels play pivotal roles in neuronal low-threshold spikes, visceral pain, and pacemaker activity. Phosphorylation has been reported to potently regulate the activity and gating properties of Cav 3.1 channels. However, systematic identification of phosphorylation sites (phosphosites) in Cav 3.1 channel has been poorly investigated. In this work, we analyzed rat Cav 3.1 protein expressed in HEK-293 cells by mass spectrometry, identified 30 phosphosites located at the cytoplasmic regions, and illustrated them as a Cav 3.1 phosphorylation map which includes the reported mouse Cav 3.1 phosphosites. Site-directed mutagenesis of the phosphosites to Ala residues and functional analysis of the phospho-silent Cav 3.1 mutants expressed in Xenopus oocytes showed that the phospho-silent mutation of the N-terminal Ser18 reduced its current amplitude with accelerated current kinetics and negatively shifted channel availability. Remarkably, the phospho-silent mutations of the C-terminal Ser residues (Ser1924, Ser2001, Ser2163, Ser2166, or Ser2189) greatly reduced their current amplitude without altering the voltage-dependent gating properties. In contrast, the phosphomimetic Asp mutations of Cav 3.1 on the N- and C-terminal Ser residues reversed the effects of the phospho-silent mutations. Collectively, these findings demonstrate that the multiple phosphosites of Cav 3.1 at the N- and C-terminal regions play crucial roles in the regulation of the channel activity and voltage-dependent gating properties.

Sites and Regulation of L-Type Ca2+ Channel Cav1.2 Phosphorylation in Brain.

Cav1.2 channel phosphorylation plays an important role in regulating neuronal plasticity by action potential-dependent Ca2+ entry. Most studies of Cav1.2 regulation by phosphorylation have been reported in heart and muscles. Here, we identified phosphorylation sites of neuronal Cav1.2 channel protein purified from rat brain using mass spectrometry. The functional characterization of these phosphorylation sites showed altered voltage-dependent biophysical properties of the channel, without affecting current density. These results show that neuronal Cav1.2 channel is regulated by phosphorylation in a complex mechanism involving multiple phosphorylation sites.

Snapin Specifically Up-Regulates Cav1.3 Ca2+ Channel Variant with a Long Carboxyl Terminus.

Ca2+ entry through Cav1.3 Ca2+ channels plays essential roles in diverse physiological events. We employed yeast-two-hybrid (Y2H) assays to mine novel proteins interacting with Cav1.3 and found Snapin2, a synaptic protein, as a partner interacting with the long carboxyl terminus (CTL) of rat Cav1.3L variant. Co-expression of Snapin with Cav1.3L/Cavß3/α2δ2 subunits increased the peak current density or amplitude by about 2-fold in HEK-293 cells and Xenopus oocytes, without affecting voltage-dependent gating properties and calcium-dependent inactivation. However, the Snapin up-regulation effect was not found for rat Cav1.3S containing a short CT (CTS) in which a Snapin interaction site in the CTL was deficient. Luminometry and electrophysiology studies uncovered that Snapin co-expression did not alter the membrane expression of HA tagged Cav1.3L but increased the slope of tail current amplitudes plotted against ON-gating currents, indicating that Snapin increases the opening probability of Cav1.3L. Taken together, our results strongly suggest that Snapin directly interacts with the CTL of Cav1.3L, leading to up-regulation of Cav1.3L channel activity via facilitating channel opening probability.

Impacts of undernutrition and maternal oral health status on dental caries in Korean children aged 3-5 years.

INTRODUCTION: The association between nutrition and oral health has been studied in the elderly. This study aimed to examine the impacts of undernutrition and the mothers' socioeconomic and oral health statuses on the incidence of dental caries in Korean preschool children. METHODS: Data of 610 children aged 3-5 years and their mothers who underwent oral examinations and responded to the questionnaires in the 6th KNAHNES were used. Caries prevalence was measured by dft and dt among the primary teeth in children and DMFT among mothers. Dietary reference intake values were used to evaluate nutritional status, a nutritional quality index and the mean nutrient adequacy ratio. Complex sample correlation analysis was performed by using children's dft and dt statuses as dependent variables. Multilevel linear regression was applied to investigate the impacts of undernutrition and mothers' socioeconomic and oral health status on children's dft and dt statuses. Statistical significance was set as P < .05. RESULTS: Factors significantly related to dft in children were age and food. Food insecurity was the only factor significantly associated with dt in children. Children's sex and mother's DMFT were likely to be relevant to dft in children. Children's age and a nutritional quality index value less than 1 were also likely to be relevant to the dt of children. CONCLUSIONS: Children with an undernourished status had a higher caries experience. A comprehensive community dental health promotion programme should be developed to prevent the incidence of dental caries in vulnerable undernourished children.

Real-Time Noninvasive Measurement of Glucose Concentration Using a Modified Hilbert Shaped Microwave Sensor.

We developed a microwave glucose sensor based on the modified first-order Hilbert curve design and measured glucose concentration in aqueous solutions by using a real-time microwave near-field electromagnetic interaction technique. We observed S21 transmission parameters of the sensor at resonant frequencies depend on the glucose concentration. We could determine the glucose concentration in the 0-250 mg/dL concentration range at an operating frequency of near 6 GHz. The measured minimum detectable signal was 0.0156 dB/(mg/dL) and the measured minimum detectable concentration was 1.92 mg/dL. The simulation result for the minimum detectable signal and the minimum detectable concentration was 0.0182 dB/(mg/dL) and 1.65 mg/dL, respectively. The temperature instability of the sensor for human glycemia in situ measurement range (27-34 °C for fingers and 36-40 °C for body temperature ranges) can be improved by the integration of the temperature sensor in the microwave stripline platform and the obtained data can be corrected during signal processing. The microwave signal-temperature dependence is almost linear with the same slope for a glucose concentration range of 50-150 mg/dL. The temperature correlation coefficient is 0.05 dB/°C and 0.15 dB/°C in 27-34 °C and 36-40 °C temperature range, respectively. The presented system has a cheap, easy fabrication process and has great potential for non-invasive glucose monitoring.

Neuronal calcium channel α1 subunit interacts with AMPA receptor, increasing its cell surface localisation.

Voltage-activated Ca2+ channels (Cav) play critical roles in excitable cells including neurons. Unlike the well-defined roles of Cav2 for pre-synaptic neurotransmission, the post-synaptic function of Cav2 is unclear. Based on our previous study demonstrating the postsynaptic association of the Cav2 with the AMPA receptor (AMPA-R), in this study we sought to further analyse the Cav2-AMPA-R association. We used a step-by-step dissociation of partially purified native Cav2-AMPA-R complexes and co-immunoprecipitation of the Cav2-AMPA-R complexes expressed in HEK293T cells to demonstrate that the main subunit of Cav, α1, formed a complex with the AMPA-R without the auxiliary subunits ß, α2δ, γ2/3. The α1 subunit increased the cell-surface localisation of the AMPA-R, which could be a post-synaptic function of the Cav2.

Ca2+ Regulation of Cav3.3 T-type Ca2+ Channel Is Mediated by Calmodulin.

Calcium-dependent inactivation of high voltage-activated Ca2+ channels plays a crucial role in limiting rises in intracellular calcium (Ca2+i). A key mediator of these effects is calmodulin, which has been found to bind the C-terminus of the pore-forming α subunit. In contrast, little is known about how Ca2+i can regulate low voltage-activated T-type Ca2+ channels. Using whole cell patch clamp, we examined the biophysical properties of Ca2+ current through the three T-type Ca2+ channel isoforms, Cav3.1, Cav3.2, or Cav3.3, comparing internal solutions containing 27 nM and l µM free Ca2+ Both activation and inactivation kinetics of Cav3.3 current in l µM Ca2+i solution were more rapid than those in 27 nM Ca2+i solution. In addition, both activation and steady-state inactivation curves of Cav3.3 were negatively shifted in the higher Ca2+i solution. In contrast, the biophysical properties of Cav3.1 and Cav3.2 isoforms were not significantly different between the two internal solutions. Overexpression of CaM1234 (a calmodulin mutant that doesn't bind Ca2+) occluded the effects of l µM Ca2+i on Cav3.3, implying that CaM is involved in the Ca2+i regulation effects on Cav3.3. Yeast two-hybrid screening and co-immunoprecipitation experiments revealed a direct interaction of CaM with the carboxyl terminus of Cav3.3. Taken together, our results suggest that Cav3.3 T-type channel is potently regulated by Ca2+i via interaction of Ca2+/CaM with the carboxyl terminus of Cav3.3.

Association of stress, depression, and suicidal ideation with subjective oral health status and oral functions in Korean adults aged 35 years or more.

BACKGROUND: Oral health greatly affects well-being throughout the different stages of life from childhood to late adulthood. Loss of teeth due to poor oral health hinders mastication, leading to poor nutrition absorption, and affects pronunciation and aesthetics, leading to interpersonal difficulties. As social activities become limited, a sense of isolation and loneliness, stress, and depression grows while happiness decreases. This study aimed to examine the association of stress, depression, and suicidal ideation with oral health status and oral functions in a large nationwide sample of Korean adults aged 35 years or more. METHODS: The sample comprised 15,716 adults, selected using a rolling survey sampling method and data were extracted from the Fifth Korea National Health and Nutrition Examination Survey (KNHANES) (2010-2012). Participants were interviewed about their self-evaluation of health including oral health status and mental health, such as stress, depression, and suicidal ideation. Data from 11,347 adults were finally selected after excluding participants with missing answers. The dependent variables were stress, depression, and suicidal ideation. The independent variables were gender, age, household income, education, smoking, drinking, oral health perception, chewing, and speaking. Complex samples logistic regression analyses were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Participants met the criteria for stress (25.4%), depression (13.0%), and suicidal ideation (13.9%). Subjective oral health status was not significantly associated with stress, depression, and suicidal ideation. However, the presence of very uncomfortable chewing problems was significantly associated with stress (OR = 2.294, 95% CI = 1.41, 3.72), depression (OR = 3.232, 95% CI = 1.97, 5.31), and suicidal ideation (OR = 2.727, 95% CI = 1.58, 4.72). The presence of very uncomfortable speaking problems was significantly associated with stress (OR = 1.592, 95% CI = 1.13, 2.24) but not significantly associated with depression and suicidal ideation. CONCLUSIONS: Oral functional problems including chewing and speaking difficulties can be associated with mental health. It is necessary to develop oral health promotion programs for adults and help them maintain a good quality of life and mental health.

Differential zinc permeation and blockade of L-type Ca2+ channel isoforms Cav1.2 and Cav1.3.

Certain voltage-activated Ca2+ channels have been reported to act as potential zinc entry routes. However, it remains to be determined whether zinc can permeate individual Ca2+ channel isoforms. We expressed recombinant Ca2+ channel isoforms in Xenopus oocytes and attempted to record zinc currents from them using a two-electrode voltage clamp method. We found that, in an extracellular zinc solution, inward currents arising from zinc permeation could be recorded from Xenopus oocytes expressing L-type Cav1.2 or Cav1.3 isoforms, but not from oocytes expressing Cav2.2, Cav2.3, Cav3.1, or Cav3.2. Zinc currents through Cav1.2 and Cav1.3 were blocked by nimodipine, but enhanced by (±)Bay K8644, supporting the finding that zinc can permeate both L-type Cav1.2 and Cav1.3 channel isoforms. We also examined the blocking effects of low concentrations of zinc on Ca2+ currents through the L-type channel isoforms. Low micro-molar zinc potently blocked Ca2+ currents through Cav1.2 and Cav1.3 with different sensitivities (IC50 for Cav1.2 and Cav1.3=18.4 and 34.1 µM) and de-accelerated the activation and inactivation kinetics in a concentration-dependent manner. Notably, mild acidifications of the external zinc solution increased zinc currents through Cav1.2 and Cav1.3, with the increment level for Cav1.3 being greater than that for Cav1.2. In overall, we provide evidence that Cav1.2 and Cav1.3 isoforms are capable of potentially functioning as zinc permeation routes, through which zinc entry can be differentially augmented by mild acidifications.

Mistic-fused expression of algal rhodopsins in Escherichia coli and its photochemical properties.

BACKGROUND: Since algal rhodopsins, the eukaryotic seven-transmembrane proteins, are generally difficult to express in Escherichia coli, eukaryotic cells have been used for heterologous expression. Mistic, a membrane-associated protein that was originally discovered in Bacillus subtilis, has been shown to improve the expression levels of many foreign integral membrane proteins in E. coli when used as a fusion partner linked to the N-terminus of cargo proteins. METHODS: Here, we expressed two algal rhodopsins with N- and C-terminal Mistic domains in E. coli-Acetabularia rhodopsin I (ARI) and Chlamydomonas sensory rhodopsin B (CSRB, channel rhodopsin 2). UV/VIS spectroscopy, pH titration of proton acceptor residue, laser-induced photolysis and electrophysiological measurement were used for investigating important residues in proton transport and spectroscopic characters of the proteins. RESULTS: Protein yield of two algal rhodopsins was enhanced, obtaining 0.12mg of Mistic-ARI and 0.04mg of Mistic-CSRB per liter of culture. Spheroplast expression Mistic-ARI had outward proton-pumping activity, indicating protein functionality. Asp89 of ARI changed its protonation state by light absorption, and Asp100 was important for O(600) formation. Electrophysiology revealed that both residues took part in proton transport. The spectroscopic analyses of Mistic-CSRB revealed its characteristics. CONCLUSIONS: Fusion to the membrane-integrating protein Mistic can enhance overexpression of eukaryotic type I rhodopsins in E. coli. GENERAL SIGNIFICANCE: These findings indicate that Mistic fusion and E. coli expression method could be an effective, low cost technique for studying eukaryotic membrane proteins. This may have useful implications, for example, in studying structural characteristics and optogenetics for rhodopsins.

Ins and outs of T-channel structure function.

We review the ins and outs of T-channel structure, focusing on the extracellular high-affinity metal-binding site and intracellular loops. The high-affinity metal-binding site was localized to repeat I of Cav3.2. Interestingly, a similar binding site was found in the high voltage-activated Cav2.3 channel where it controls the channels' voltage dependence. Histidine at position 191 has a particularly interesting role in the high-affinity binding site, and its modification plays an important role in channel regulation by pharmacological agents that alter redox reactions. The intracellular loop connecting repeats I and II plays two important roles in Cav3.2 properties: one, its gating; and two, its surface expression. These studies have also identified a highly conserved intracellular gating brake that is predicted to form a helix-loop-helix structure. We conclude that the gating brake establishes important contacts with the gating machinery, thereby stabilizing a closed state of T-channels. This interaction is disrupted by depolarization, allowing the S6 segments to open and allowing Ca(2+) ions to flow through. Studies in cultured hippocampal neurons provided novel insights into how mutations found in idiopathic generalized epilepsy patients increase seizure susceptibility by both altering T-current pacemaker currents and by activating Ca-activated transcription factors that regulate dendritic arborization. These studies reveal novel roles for T-channels to control cellular physiology.

Synthetic K⁺/Cl⁻-selective symporter across a phospholipid membrane.

Synthetic molecules which selectively transport sodium or potassium chloride across a lipid membrane have been prepared. The salt carriers consist of two heteroditopic binding sites, an anion-binding cavity with three hydrogen bond donors and an azacrown ether for binding an alkali metal cation. The association constants between the carriers and chloride ion have been enhanced by 1 order of the magnitude in the presence of sodium or potassium ion in 10% (v/v) CD3OH/CD3CN, due to the formation of a contact ion-pair between the bound cation and chloride as demonstrated by the single-crystal X-ray structure of a sodium chloride complex. A series of transport experiments have demonstrated that the synthetic molecule functions as a mobile carrier of transporting salts via M(+)/Cl(-) symport. Among alkali metal chlorides, the carrier with an 18-azacrown-6 exhibits a strong selectivity toward potassium chloride, while the carrier with a 15-azacrown-5 displays a moderate selectivity for sodium chloride.

Clinical value of tranexamic acid in unilateral and simultaneous bilateral TKAs under a contemporary blood-saving protocol: a randomized controlled trial.

PURPOSE: Despite the documented blood-saving effects of tranexamic acid (TNA) in total knee arthroplasty (TKA), the question whether clinical values of TNA are identical in unilateral and bilateral TKAs remains unclear. This study was undertaken to determine the clinical values of TNA in unilateral and simultaneous bilateral TKAs under a contemporary blood-saving protocol in terms of efficacy (total blood loss and transfusion rate) and safety (the incidences of symptomatic deep vein thrombosis and pulmonary embolism). METHODS: One hundred and eighty unilateral and 146 bilateral TKA patients were randomized into TNA group or control group. In unilateral TKA patients, TNA (10 mg/kg) was administered intravenously 20 min before tourniquet deflation and repeated 3 h after surgery. In bilateral TKA patients, one more dose (10 mg/kg) was given before tourniquet deflation in the second TKA. A contemporary blood-saving protocol was applied to all patients. The TNA and control groups were compared separately in unilateral and bilateral TKA patients for the efficacy and safety variables. RESULTS: In unilateral TKA patients, the TNA group had less total blood loss (905 vs. 1,018 mL, p = 0.018) than the control group, but there was no difference in the allogenic transfusion rate (1 vs. 7 %, n.s.). In bilateral TKA patients, the TNA group showed no differences in total blood loss (1,282 vs. 1,379 mL, n.s.), but a significant reduction in the allogenic transfusion rate (7 vs. 27 %, p = 0.002). No symptomatic deep vein thrombosis or pulmonary embolism was found in all patients. CONCLUSION: This study demonstrates that the use of TNA reduces total blood loss, but the effects on the transfusion rate can differ depending on the type of TKAs (unilateral vs. bilateral) and the blood-saving protocols.

G protein ß subunits regulate Cav3.3 T-type channel activity and current kinetics via interaction with the Cav3.3 C-terminus.

Ca2+ influx through Cav3.3 T-type channel plays crucial roles in neuronal excitability and is subject to regulation by various signaling molecules. However, our understanding of the partners of Cav3.3 and the related regulatory pathways remains largely limited. To address this quest, we employed the rat Cav3.3 C-terminus as bait in yeast-two-hybrid screenings of a cDNA library, identifying rat Gß2 as an interaction partner. Subsequent assays revealed that the interaction of Gß2 subunit was specific to the Cav3.3 C-terminus. Through systematic dissection of the C-terminus, we pinpointed a 22 amino acid sequence (amino acids 1789-1810) as the Gß2 interaction site. Coexpression studies of rat Cav3.3 with various Gßγ compositions were conducted in HEK-293 cells. Patch clamp recordings revealed that coexpression of Gß2γ2 reduced Cav3.3 current density and accelerated inactivation kinetics. Interestingly, the effects were not unique to Gß2γ2, but were mimicked by Gß2 alone as well as other Gßγ dimers, with similar potencies. Deletion of the Gß2 interaction site abolished the effects of Gß2γ2. Importantly, these Gß2 effects were reproduced in human Cav3.3. Overall, our findings provide evidence that Gß(γ) complexes inhibit Cav3.3 channel activity and accelerate the inactivation kinetics through the Gß interaction with the Cav3.3 C-terminus.

Effects of eugenol on T-type Ca2+ channel isoforms.

Eugenol has been used as an analgesic in dentistry. Previous studies have demonstrated that voltage-gated Na(+) channels and high-voltage-activated Ca(2+) channels expressed in trigeminal ganglion (TG) neurons sensing dental pain are molecular targets of eugenol for its analgesic effects. However, it has not been investigated whether eugenol can affect T-type Ca(2+) channels, which are known to be detected in the afferent neurons. In this report, we investigate how eugenol can influence cloned T-type channel isoforms expressed in HEK293 cells, using whole-cell patch clamp. Application of eugenol inhibited Cav3.1, Cav3.2, and Cav3.3 currents in a concentration-dependent manner with IC50 values of 463, 486, and 708 µM, respectively. Eugenol was found to negatively shift the steady-state inactivation curves of the T-type channel isoforms, but it did not shift their activation curves. In addition, eugenol had little effect on the current kinetics of Cav3.1 and Cav3.2, but it accelerated the inactivation kinetics of Cav3.3 currents. Reduction of channel availability enhanced eugenol inhibition sensitivity for Cav3.1 and Cav3.2, but not for Cav3.3. Moreover, eugenol inhibition of T-type channel isoforms was found to be use dependent. Finally, we show that the T-type currents recorded from rat TG neurons were inhibited by eugenol with a similar potency to Cav3.1 and Cav3.2 isoforms. Taken together, our findings suggest that T-type Ca(2+) channels are additional molecular targets for the pain-relieving effects of eugenol.

A post-burst after depolarization is mediated by group i metabotropic glutamate receptor-dependent upregulation of Ca(v)2.3 R-type calcium channels in CA1 pyramidal neurons.

Activation of group I metabotropic glutamate receptors (subtypes mGluR1 and mGluR5) regulates neural activity in a variety of ways. In CA1 pyramidal neurons, activation of group I mGluRs eliminates the post-burst afterhyperpolarization (AHP) and produces an afterdepolarization (ADP) in its place. Here we show that upregulation of Ca(v)2.3 R-type calcium channels is responsible for a component of the ADP lasting several hundred milliseconds. This medium-duration ADP is rapidly and reversibly induced by activation of mGluR5 and requires activation of phospholipase C (PLC) and release of calcium from internal stores. Effects of mGluR activation on subthreshold membrane potential changes are negligible but are large following action potential firing. Furthermore, the medium ADP exhibits a biphasic activity dependence consisting of short-term facilitation and longer-term inhibition. These findings suggest that mGluRs may dramatically alter the firing of CA1 pyramidal neurons via a complex, activity-dependent modulation of Ca(v)2.3 R-type channels that are activated during spiking at physiologically relevant rates and patterns.

Preemptive low-dose dexamethasone reduces postoperative emesis and pain after TKA: a randomized controlled study.

BACKGROUND: Dexamethasone is a potent analgesic and antiemetic. However, the benefit of dexamethasone after TKA is unclear, as is the efficacy in a current multimodal regime. QUESTIONS/PURPOSES: We determined (1) whether the addition of dexamethasone to a protocol including ramosetron further reduces postoperative emesis compared with ramosetron alone; (2) whether it reduces postoperative pain; and (3) whether it increases the risk for wound complications in a current multimodal regime after TKA. METHODS: We randomized 269 patients undergoing TKAs to receive dexamethasone (10 mg) 1 hour before surgery and ramosetron immediately after surgery (Dexa-Ra group, n = 135), or ramosetron alone (Ra group, n = 134). We recorded the incidence of postoperative nausea and vomiting (PONV), severity of nausea, incidence of antiemetic requirement, complete response, pain level, and opioid consumption. Patients were assessed 0 to 6, 6 to 24, 24 to 48, and 48 to 72 hours postoperatively. In addition, patients were evaluated for wound complications and periprosthetic joint infections at a minimum of 1 year after surgery. RESULTS: The Dexa-Ra group had a lower incidence of PONV during the entire 72-hour evaluation period and experienced less severe nausea for the first 6 hours after TKA, although not between 6 to 72 hours. Overall use of a rescue antiemetic was less frequent, and complete response was more frequent in the Dexa-Ra group. Patients in the Dexa-Ra group experienced lower pain and consumed less opioids during the 6- to 24-hour period and during the overall study period. No differences were found in wound complications between the groups, and each group had one case of periprosthetic joint infection. CONCLUSIONS: Patients who received prophylactic dexamethasone in addition to ramosetron had reduced postoperative emesis and pain without increased risks for wound complications, compared with patients who received ramosetron alone in patients managed using a multimodal regimen after TKA.

Case report: Generalized lymphatic anomaly of multiple abdominal organs in a young dog.

A 9-month-old, female Pomeranian dog presented with vomiting and lethargy. Ultrasonography revealed multilobulated anechoic round shape structures at the ovarian and uterine locations. Through computed tomography scan, an extensive non-contrast multilobulated fluid-filled mass suspected of originating from the walls of the ovary, uterus, urinary bladder and rectum was observed. Ovariohysterectomy and urinary bladder biopsy were performed. Histopathological examination revealed numerous cystic lesions lined by plump cuboidal cells believed to be of epithelial origin. Immunohistochemical staining showed that the cyst-like lesions lining cells were strongly positive for lymphatic vessel endothelial hyaluronan receptor 1. Based on these results, lesions were identified as generalized lymphatic anomaly (GLA), in which lymphangiomas develop in multiple organs. After 6 months follow-up, the size of the cysts remaining in the region of the bladder did not undergo much change. GLA should be included in the differential diagnosis when multiple cystic lesions are interspersed in multiple organs.

Molecular cloning and characterization of a hamster Cav1.3 Ca2+ channel variant with a long carboxyl terminus.

We have cloned a hamster Cav1.3 variant with a long carboxyl terminus. This differs from the first hamster Cav1.3 clone which has a short carboxyl terminus. When relative expression levels of the two variants were examined using quantitative RT-PCR, the long Cav1.3 transcripts were detected abundantly in the brain and testis, moderately in the heart, pancreas, and kidney, and weakly in the lung. Comparatively, the short Cav1.3 transcripts were detected less abundantly in most of the tissues. The two Cav1.3 variants were reconstituted in Xenopus oocytes and their electrophysiological properties were characterized using a two-electrode voltage clamping method. The long Cav1.3 variant was ~5-fold better expressed than the short Cav1.3 variant. When Ca2+ was used as a charge carrier, the long Cav1.3 variant containing an IQ (Ile-Gln) motif displayed strong calcium-dependent inactivation, while the short variant that was deficient of an IQ motif showed little calcium-dependent inactivation. Examination of other biophysical properties revealed that potentials for activation threshold, peak current, and half-activation and inactivation of the long Cav1.3 were significantly lower than those of the short Cav1.3. These findings suggest that the long carboxyl tail plays crucial roles in not only facilitating calcium-dependent inactivation, but also improving expression and negative shifting of the activation and inactivation properties.

3D visualization of microwave electric and magnetic fields by using a metasurface-based indicator.

Visualizations of the microwave electric and magnetic near-field distributions of radio-frequency (RF) filters were performed using the technique of thermoelastic optical indicator microscopy (TEOIM). New optical indicators based on periodic dielectric-metal structures were designed for electric field visualization. Depending on the structure orientation, such metasurface-based indicators allow separately visualization of the Ex and Ey components of the in-plane electric field. Numerical simulations were conducted to examine the working principle of the designed indicator structures, and the results were compared to the experimental, showing good agreement. In addition, the 3D visualization of the microwave near-field distribution was built, to show the field intensity and distribution dependencies on the distance from the RF filter.