scholarly journals Electrophysiological Properties of Calcium-Sensitiser Levosimendan During Rewarming From Severe Hypothermia In Vivo

2017 ◽  
Vol 39 (8) ◽  
pp. e35-e36
Author(s):  
E.S. Dietrichs ◽  
B. Håheim ◽  
T. Kondratiev ◽  
T. Tveita
Keyword(s):  
Electrophysiological Properties ◽  
Severe Hypothermia ◽  
Calcium Sensitiser

scholarly journals Two Drosophila Innexins Are Expressed in Overlapping Domains and Cooperate to Form Gap-Junction Channels

2000 ◽  
Vol 11 (7) ◽  
pp. 2459-2470 ◽  
Author(s):  
Lucy A. Stebbings ◽  
Martin G. Todman ◽  
Pauline Phelan ◽  
Jonathan P. Bacon ◽  
Jane A. Davies
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Ectopic Expression ◽  
In Vivo Studies ◽  
Electrophysiological Properties ◽  
Gap Junction Channels ◽  
Overlapping Domains ◽  
In Vitro Data

Members of the innexin protein family are structural components of invertebrate gap junctions and are analogous to vertebrate connexins. Here we investigate two Drosophila innexin genes,Dm-inx2 and Dm-inx3 and show that they are expressed in overlapping domains throughout embryogenesis, most notably in epidermal cells bordering each segment. We also explore the gap-junction–forming capabilities of the encoded proteins. In pairedXenopus oocytes, the injection of Dm-inx2mRNA results in the formation of voltage-sensitive channels in only ∼ 40% of cell pairs. In contrast, Dm-Inx3 never forms channels. Crucially, when both mRNAs are coexpressed, functional channels are formed reliably, and the electrophysiological properties of these channels distinguish them from those formed by Dm-Inx2 alone. We relate these in vitro data to in vivo studies. Ectopic expression ofDm-inx2 in vivo has limited effects on the viability ofDrosophila, and animals ectopically expressingDm-inx3 are unaffected. However, ectopic expression of both transcripts together severely reduces viability, presumably because of the formation of inappropriate gap junctions. We conclude that Dm-Inx2 and Dm-Inx3, which are expressed in overlapping domains during embryogenesis, can form oligomeric gap-junction channels.

A new implantable tool for repeated assessment of supraventricular electrophysiology and atrial fibrillation susceptibility in freely moving rats

2020 ◽  
Author(s):  
Michael Murninkas ◽  
Roni Gillis ◽  
Danielle I Lee ◽  
Sigal Elyagon ◽  
Nikhil Suresh Bhandarkar ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Ex Vivo ◽  
Adult Rats ◽  
Electrophysiological Properties ◽  
Multiple Risk Factors ◽  
Electrophysiological Studies ◽  
Cycle Lengths ◽  
Major Factors

The complex pathophysiology of atrial fibrillation (AF) is governed by multiple risk factors in ways that are still elusive. Basic electrophysiological properties including atrial effective refractory period (AERP) and conduction velocity are major factors determining the susceptibility of the atrial myocardium to AF. Although there is a great need for affordable animal models in this field of research, in-vivo rodent studies are limited by technical challenges. Recently, we introduced an implantable system for long-term assessment of AF susceptibility in ambulatory rats. However, technical considerations did not allow us to perform concomitant supraventricular electrophysiology measurements. Here, we designed a novel quadripolar-electrode specifically adapted for comprehensive atrial studies in ambulatory rats. Electrodes were fabricated from medical-grade silicone, four platinum-iridium poles and stainless steel fixating pins. Initial quality validation was performed ex-vivo, followed by implantation in adult rats and repeated electrophysiological studies 1, 4 and 8 weeks post implantation. Capture threshold was stable. Baseline AERP values (38.1±2.3 and 39.5±2.0 using 70ms and 120ms S1-S1 cycle lengths, respectively) confirmed the expected absence of rate-adaptation in the unanesthetized state and validated our prediction that markedly higher values reported under anesthesia are non-physiological. Evaluation of AF substrate in parallel with electrophysiological parameters validated our recent finding of a gradual increase in AF susceptibility over-time and demonstrated that this phenomenon is associated with an electrical remodeling process characterized by AERP shortening. Our findings indicate that the miniature quadripolar-electrode is a potent new tool, which opens a window of opportunities for better utilization of rats in AF research.

scholarly journals Arrhythmia susceptibility in senescent rat hearts

2014 ◽  
Vol 87 (1) ◽  
Author(s):  
Stefano Rossi ◽  
Silvana Baruffi ◽  
Domenico Corradi ◽  
Sergio Callegari ◽  
Ezio Musso ◽  
...  
Keyword(s):  
Cardiac Electrophysiology ◽  
The Elderly ◽  
Detailed Knowledge ◽  
Activation Patterns ◽  
Electrophysiological Properties ◽  
Age Related ◽  
Rat Hearts ◽  
Arrhythmogenic Substrate ◽  
Ventricular Activation

Cardiovascular disease increases with age as well as alterations of cardiac electrophysiological properties, but a detailed knowledge about changes in cardiac electrophysiology relevant to arrhythmogenesis in the elderly is relatively lacking. The aim of this study was to determine specific age-related changes in electrophysiological properties of the ventricles which can be related to a structural-functional arrhythmogenic substrate. Multiple epicardial electrograms were recorded on the ventricular surface of in vivo control and aged rats, while arrhythmia vulnerability was investigated by premature stimulation protocols. Single or multiple ectopic beats and sustained ventricular arrhythmias were frequently induced in aged but not in control hearts. Abnormal ventricular activation patterns during sinus rhythm and unchanged conduction velocity during point stimulation in aged hearts suggest the occurrence of impaired impulse conduction through the distal Purkinje system that might create a potential reentry substrate.

Electrophysiological properties of mouse dopamine neurons: In vivo and in vitro studies

Neuroscience ◽  
1984 ◽  
Vol 12 (3) ◽  
pp. 793-801 ◽  
Author(s):  
M.K. Sanghera ◽  
M.E. Trulson ◽  
D.C. German
Keyword(s):  
In Vitro Studies ◽  
Dopamine Neurons ◽  
Electrophysiological Properties

Effect of Colchicine on the Electrophysiological Properties of the Toad Sciatic-Gastrocnemius Preparations in vivo

Pharmacology ◽  
1982 ◽  
Vol 25 (5) ◽  
pp. 278-285
Author(s):  
J.C. Sáez ◽  
B. Norris ◽  
J. Concha
Keyword(s):  
Electrophysiological Properties

Acidosis-Stimulated Neurons of the Medullary Raphe Are Serotonergic

2001 ◽  
Vol 85 (5) ◽  
pp. 2224-2235 ◽  
Author(s):  
Wengang Wang ◽  
Jyoti K. Tiwari ◽  
Stefania Risso Bradley ◽  
Rey V. Zaykin ◽  
George B. Richerson
Keyword(s):  
Cell Culture ◽  
Substance P ◽  
Tryptophan Hydroxylase ◽  
Brain Slices ◽  
Serotonergic Neurons ◽  
Electrophysiological Properties ◽  
Medullary Raphe ◽  
Raphe Neurons

Neurons of the medullary raphe project widely to respiratory and autonomic nuclei and contain co-localized serotonin, thyrotropin-releasing hormone (TRH), and substance P, three neurotransmitters known to stimulate ventilation. Some medullary raphe neurons are highly sensitive to pH and CO2 and have been proposed to be central chemoreceptors. Here it was determined whether these chemosensitive neurons are serotonergic. Cells were microdissected from the rat medullary raphe and maintained in primary cell culture for 13–70 days. Immunoreactivity for serotonin, substance P, and TRH was present in these cultures. All acidosis-stimulated neurons ( n = 22) were immunoreactive for tryptophan hydroxylase (TpOH-IR), the rate-limiting enzyme for serotonin biosynthesis, whereas all acidosis-inhibited neurons ( n= 16) were TpOH-immunonegative. The majority of TpOH-IR medullary raphe neurons (73%) were stimulated by acidosis. The electrophysiological properties of TpOH-IR neurons in culture were similar to those previously reported for serotonergic neurons in vivo and in brain slices. These properties included wide action potentials (4.55 ± 0.5 ms) with a low variability of the interspike interval, a postspike afterhyperpolarization (AHP) that reversed 25 mV more positive than the Nernst potential for K+, prominent A current, spike frequency adaptation and a prolonged AHP after a depolarizing pulse. Thus the intrinsic cellular properties of serotonergic neurons were preserved in cell culture, indicating that the results obtained using this in vitro approach are relevant to serotonergic neurons in vivo. These results demonstrate that acidosis-stimulated neurons of the medullary raphe contain serotonin. We propose that serotonergic neurons initiate a homeostatic response to changes in blood CO2 that includes increased ventilation and modulation of autonomic function.

Sign in / Sign up

Export Citation Format

Share Document