A TTX-Sensitive Resting Na+ Permeability Contributes to the Catecholaminergic Automatic Activity in Rat Pulmonary Vein

2014 ◽  
Vol 26 (3) ◽  
pp. 311-319 ◽  
Author(s):  
CLAIRE O. MALÉCOT ◽  
PIERRE BREDELOUX ◽  
IAN FINDLAY ◽  
VÉRONIQUE MAUPOIL
Keyword(s):  
Pulmonary Vein ◽  
Automatic Activity ◽  
Na Permeability

Catecholaminergic automatic activity in the rat pulmonary vein: electrophysiological differences between cardiac muscle in the left atrium and pulmonary vein

2009 ◽  
Vol 297 (1) ◽  
pp. H102-H108 ◽  
Author(s):  
Nicolas Doisne ◽  
Véronique Maupoil ◽  
Pierre Cosnay ◽  
Ian Findlay
Keyword(s):  
Membrane Potential ◽  
Electrical Activity ◽  
Cardiac Muscle ◽  
Left Atrium ◽  
Pulmonary Vein ◽  
Pulmonary Veins ◽  
Muscle Membrane ◽  
Resting Membrane Potential ◽  
Ectopic Activity ◽  
Automatic Activity

Ectopic activity in cardiac muscle within pulmonary veins (PVs) is associated with the onset and the maintenance of atrial fibrillation in humans. The mechanism underlying this ectopic activity is unknown. Here we investigate automatic activity generated by catecholaminergic stimulation in the rat PV. Intracellular microelectrodes were used to record electrical activity in isolated strips of rat PV and left atrium (LA). The resting cardiac muscle membrane potential was lower in PV [−70 ± 1 (SE) mV, n = 8] than in LA (−85 ± 1 mV, n = 8). No spontaneous activity was recorded in PV or LA under basal conditions. Norepinephrine (10−5 M) induced first a hyperpolarization (−8 ± 1 mV in PV, −3 ± 1 mV in LA, n = 8 for both) then a slowly developing depolarization (+21 ± 2 mV after 15 min in PV, +1 ± 2 mV in LA) of the resting membrane potential. Automatic activity occurred only in PV; it was triggered at approximately −50 mV, and it occurred as repetitive bursts of slow action potentials. The diastolic membrane potential increased during a burst and slowly depolarized between bursts. Automatic activity in the PV was blocked by either atenolol or prazosine, and it could be generated with a mixture of cirazoline and isoprenaline. In both tissues, cirazoline (10−6 M) induced a depolarization (+37 ± 2 mV in PV, n = 5; +5 ± 1 mV in LA, n = 5), and isoprenaline (10−7 M) evoked a hyperpolarization (−11 ± 3 mV in PV, n = 7; −3 ± 1 mV in LA, n = 6). The differences in membrane potential and reaction to adrenergic stimulation lead to automatic electrical activity occurring specifically in cardiac muscle in the PV.

scholarly journals Automatic Activity Arising in Cardiac Muscle Sleeves of the Pulmonary Vein

Biomolecules ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 23
Author(s):  
Pierre Bredeloux ◽  
Come Pasqualin ◽  
Romain Bordy ◽  
Veronique Maupoil ◽  
Ian Findlay
Keyword(s):  
Cardiac Muscle ◽  
Pulmonary Vein ◽  
Left Atrial ◽  
Large Scale ◽  
Pulmonary Veins ◽  
Cellular Heterogeneity ◽  
Ectopic Activity ◽  
Automatic Activity ◽  
Multiple Signaling ◽  
Human Atrial Fibrillation

Ectopic activity in the pulmonary vein cardiac muscle sleeves can both induce and maintain human atrial fibrillation. A central issue in any study of the pulmonary veins is their difference from the left atrial cardiac muscle. Here, we attempt to summarize the physiological phenomena underlying the occurrence of ectopic electrical activity in animal pulmonary veins. We emphasize that the activation of multiple signaling pathways influencing not only myocyte electrophysiology but also the means of excitation–contraction coupling may be required for the initiation of triggered or automatic activity. We also gather information regarding not only the large-scale structure of cardiac muscle sleeves but also recent studies suggesting that cellular heterogeneity may contribute to the generation of arrythmogenic phenomena and to the distinction between pulmonary vein and left atrial heart muscle.

scholarly journals Angiotensin II Induces Automatic Activity of the Isolated Guinea Pig Pulmonary Vein Myocardium through Activation of the IP3 Receptor and the Na+-Ca2+ Exchanger

2019 ◽  
Vol 20 (7) ◽  
pp. 1768 ◽  
Author(s):  
Yusuke Tanaka ◽  
Kae Obata ◽  
Tamano Ohmori ◽  
Kohei Ishiwata ◽  
Manato Abe ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Guinea Pig ◽  
Pulmonary Vein ◽  
Action Potentials ◽  
Contractile Activity ◽  
Ip3 Receptor ◽  
Potential Oscillations ◽  
Automatic Activity ◽  
Diastolic Depolarization ◽  
Membrane Potential Oscillations

The automaticity of the pulmonary vein myocardium is known to be the major cause of atrial fibrillation. We examined the involvement of angiotensin II in the automatic activity of isolated guinea pig pulmonary vein preparations. In tissue preparations, application of angiotensin II induced an automatic contractile activity; this effect was mimicked by angiotensin I and blocked by losartan, but not by PD123,319 or carvedilol. In cardiomyocytes, application of angiotensin II induced an increase in the frequency of spontaneous Ca2+ sparks and the generation of Ca2+ transients; these effects were inhibited by losartan or xestospongin C. In tissue preparations, angiotensin II caused membrane potential oscillations, which lead to repetitive generation of action potentials. Angiotensin II increased the diastolic depolarization slope of the spontaneous or evoked action potentials. These effects of angiotensin II were inhibited by SEA0400. In tissue preparations showing spontaneous firing of action potentials, losartan, xestospongin C or SEA0400 decreased the slope of the diastolic depolarization and inhibited the firing of action potentials. In conclusion, in the guinea pig pulmonary vein myocardium, angiotensin II induces the generation of automatic activity through activation of the IP3 receptor and the Na+-Ca2+ exchanger.

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