Differential action of TEA+ on two K+-current components of a molluscan neurone

1972 ◽  
Vol 336 (2) ◽  
pp. 87-100 ◽  
Author(s):  
E. Neher ◽  
H. D. Lux
Keyword(s):  
K Current ◽  
Molluscan Neurone ◽  
Differential Action

Differential Action of Phytochemicals on Platelet Apoptosis: A Biological Overview

2013 ◽  
Vol 20 (8) ◽  
pp. 1018-1027 ◽  
Author(s):  
R.M. Thushara ◽  
M. Hemshekhar ◽  
M.S. Santhosh ◽  
S. Devaraja ◽  
K. Kemparaju ◽  
...  
Keyword(s):  
Platelet Apoptosis ◽  
Differential Action

scholarly journals Canine Myocytes Represent a Good Model for Human Ventricular Cells Regarding Their Electrophysiological Properties

2021 ◽  
Vol 14 (8) ◽  
pp. 748
Author(s):  
Péter P. Nánási ◽  
Balázs Horváth ◽  
Fábián Tar ◽  
János Almássy ◽  
Norbert Szentandrássy ◽  
...  
Keyword(s):  
Action Potential ◽  
Time Course ◽  
Laboratory Animals ◽  
Delayed Rectifier ◽  
Ion Currents ◽  
Human Cardiomyocytes ◽  
Ventricular Cells ◽  
Repolarization Reserve ◽  
Electrophysiological Studies ◽  
K Current

Due to the limited availability of healthy human ventricular tissues, the most suitable animal model has to be applied for electrophysiological and pharmacological studies. This can be best identified by studying the properties of ion currents shaping the action potential in the frequently used laboratory animals, such as dogs, rabbits, guinea pigs, or rats, and comparing them to those of human cardiomyocytes. The authors of this article with the experience of three decades of electrophysiological studies, performed in mammalian and human ventricular tissues and isolated cardiomyocytes, summarize their results obtained regarding the major canine and human cardiac ion currents. Accordingly, L-type Ca2+ current (ICa), late Na+ current (INa-late), rapid and slow components of the delayed rectifier K+ current (IKr and IKs, respectively), inward rectifier K+ current (IK1), transient outward K+ current (Ito1), and Na+/Ca2+ exchange current (INCX) were characterized and compared. Importantly, many of these measurements were performed using the action potential voltage clamp technique allowing for visualization of the actual current profiles flowing during the ventricular action potential. Densities and shapes of these ion currents, as well as the action potential configuration, were similar in human and canine ventricular cells, except for the density of IK1 and the recovery kinetics of Ito. IK1 displayed a largely four-fold larger density in canine than human myocytes, and Ito recovery from inactivation displayed a somewhat different time course in the two species. On the basis of these results, it is concluded that canine ventricular cells represent a reasonably good model for human myocytes for electrophysiological studies, however, it must be borne in mind that due to their stronger IK1, the repolarization reserve is more pronounced in canine cells, and moderate differences in the frequency-dependent repolarization patterns can also be anticipated.

scholarly journals Effective Activation of BKCa Channels by QO-40 (5-(Chloromethyl)-3-(Naphthalen-1-yl)-2-(Trifluoromethyl)Pyrazolo [1,5-a]pyrimidin-7(4H)-one), Known to Be an Opener of KCNQ2/Q3 Channels

2021 ◽  
Vol 14 (5) ◽  
pp. 388
Author(s):  
Wei-Ting Chang ◽  
Sheng-Nan Wu
Keyword(s):  
Single Channel ◽  
Slow Component ◽  
Ionic Channel ◽  
Gh3 Cells ◽  
Bkca Channel ◽  
Bkca Channels ◽  
Gating Charge ◽  
Ramp Voltage ◽  
K Current ◽  
The Mean

QO-40 (5-(chloromethyl)-3-(naphthalene-1-yl)-2-(trifluoromethyl) pyrazolo[1,5-a]pyrimidin-7(4H)-one) is a novel and selective activator of KCNQ2/KCNQ3 K+ channels. However, it remains largely unknown whether this compound can modify any other type of plasmalemmal ionic channel. The effects of QO-40 on ion channels in pituitary GH3 lactotrophs were investigated in this study. QO-40 stimulated Ca2+-activated K+ current (IK(Ca)) with an EC50 value of 2.3 μM in these cells. QO-40-stimulated IK(Ca) was attenuated by the further addition of GAL-021 or paxilline but not by linopirdine or TRAM-34. In inside-out mode, this compound added to the intracellular leaflet of the detached patches stimulated large-conductance Ca2+-activated K+ (BKCa) channels with no change in single-channel conductance; however, there was a decrease in the slow component of the mean closed time of BKCa channels. The KD value required for the QO-40-mediated decrease in the slow component at the mean closure time was 1.96 μM. This compound shifted the steady-state activation curve of BKCa channels to a less positive voltage and decreased the gating charge of the channel. The application of QO-40 also increased the hysteretic strength of BKCa channels elicited by a long-lasting isosceles-triangular ramp voltage. In HEK293T cells expressing α-hSlo, QO-40 stimulated BKCa channel activity. Overall, these findings demonstrate that QO-40 can interact directly with the BKCa channel to increase the amplitude of IK(Ca) in GH3 cells.

scholarly journals TELEMEDICINE IN IBD: GOOD TRUST FROM OUTPATIENTS DURING THE COVID-19 PANDEMIC IN MILAN (LOMBARDY)

2021 ◽  
Vol 27 (Supplement_1) ◽  
pp. S51-S51
Author(s):  
Andrea Costantino ◽  
Daniele Noviello ◽  
Stefano Mazza ◽  
Roberto Berté ◽  
Maurizio Vecchi ◽  
...  
Keyword(s):  
Primary Endpoint ◽  
Assessment Tool ◽  
Healthcare Providers ◽  
Telemedicine Service ◽  
Moderate Disease ◽  
Video Consultation ◽  
K Current ◽  
Remote Assistance ◽  
Video Calling

Abstract Background and Aim During the recent COVID-19 pandemic, telemedicine has enabled many IBD patients worldwide to get access to remote assistance. Some positive reports on the use of telemedicine among patients and healthcare providers have been published1-4, but a patient’s trust perspective is not available yet. The aim of our study was to verify IBD patients’ trust in telemedicine. This study was approved by our local Ethics Committee. Material and Methods At our Gastroenterology Unit in Milan (Italy), 123 video-consultations were delivered to IBD patients with mild or moderate disease, in place of follow-up visits scheduled but not provided during the general lockdown (March-April 2020). Video-calling solutions from Google (Hangouts or Meet) or Microsoft Teams were used according to the patient’s preference. The patients’ trust in telemedicine was assessed through an adapted version of the PAtient Trust Assessment Tool (PATAT) questionnaire.5 The primary endpoint was expressed as a >75% percentage of patients giving a score of at least 4 out of 5 in a Likert Scale for three selected key statements: “I can trust video-consultation”, “I can trust that possible problems with the telemedicine service will be solved properly” and “I feel at ease when working with this website”. The questionnaire was formulated through the EUSurvey platform, widely used for clinical research questionnaires in Europe. Results One-hundred-fifteen (93.4%) video-consultations were performed out of the 123 scheduled. Among the 115 consultations, 100 questionnaires were completed (86.9%). The primary endpoint of trust in the telemedicine service was achieved in 95%, 90% and 84% of patients for the three selected key statements about the trust in the telemedicine service, its capability to solve clinical problems and its ease to use. While clinical outcomes were beyond our intentions, we reported no drugs withdrawal in this cohort nor major events. Conclusion Our results showed that during the COVID-19 pandemic most of our IBD patients accepted to receive a video-consultation in spite of the traditional in-person visit and trusted the video-consultation. References: 1. Bezzio C. et al. Gut 2020;69:1213–1217 2. George L.A., Raymond K. Current Gastroenterology Reports (2020) 22: 12 3. Lees C. W. et al. Gastroenterology 2020; 2020 May 28 4. Allocca M et al. Clin Gastroenterol Hepatol 2020;18:1882–1883 5. Velsen, L. V. et al, H. Int. J. Med. Inform 2017;97:52–58.

scholarly journals Populations of in silico myocytes and tissues reveal synergy of multiatrial‐predominant K + ‐current block in atrial fibrillation

2020 ◽  
Author(s):  
Haibo Ni ◽  
Alex Fogli Iseppe ◽  
Wayne R. Giles ◽  
Sanjiv M. Narayan ◽  
Henggui Zhang ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
In Silico ◽  
Current Block ◽  
K Current

Positive and negative contractile effects of neuropeptide Y on ventricular cardiomyocytes

1991 ◽  
Vol 261 (6) ◽  
pp. H1727-H1733 ◽  
Author(s):  
B. C. Millar ◽  
T. Weis ◽  
H. M. Piper ◽  
M. Weber ◽  
U. Borchard ◽  
...  
Keyword(s):  
Amino Acid ◽  
Neuropeptide Y ◽  
Pertussis Toxin ◽  
Contractile Response ◽  
Contractile Responses ◽  
Contractile Effect ◽  
Terminal Fragment ◽  
Ventricular Cardiomyocytes ◽  
K Current

The potency of neuropeptide Y (NPY) to cause negative and positive contractile responses in rat ventricular cardiomyocytes was investigated. In these cells, NPY was found to activate the transient outward K+ current (Ito) and the slow inward Ca2+ current (Isi). As reported before (H. M. Piper, B. C. Millar, and J. R. McDermott, Naunyn Schmiedeberg's Arch. Pharmacol. 340: 333-337, 1989), NPY attenuated the increase in the contractile response induced by isoprenaline (10(-7) M). This effect of NPY could be abolished by 1) the presence of the inhibitor of Ito, 4-aminopyridine (4-AP, 0.5 mM); 2) pretreatment of the cells with pertussis toxin (1 microgram/ml for 6 h); and 3) the presence of the 19-amino acid COOH-terminal fragment of NPY, NPY-(18-36) (10(-6) M). In the absence of isoprenaline, but in the presence of 4-AP, NPY exerted a stimulatory effect on the cardiomyocytes. This effect could be abolished 1) by using the inhibitor of the Isi, verapamil (10(-8) M), but not 2) by pretreatment with pertussis toxin, nor 3) by coincubation with NPY-(18-36). The results indicate that in the rat the antiadrenergic negative contractile effect of NPY results from its action on the Ito. Blockade of this current by 4-AP unmasks a positive contractile effect of NPY that is related to activation of the Isi.

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