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Catecholaminergic automatic activity in the rat pulmonary vein: electrophysiological differences between cardiac muscle in the left atrium and pulmonary vein
- Source :
- AJP-Heart and Circulatory Physiology, AJP-Heart and Circulatory Physiology, American Physiological Society, 2009, 297, pp.H102-H108
- Publication Year :
- 2009
- Publisher :
- HAL CCSD, 2009.
-
Abstract
- 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.
- Subjects :
- Male
medicine.medical_specialty
Adrenergic Antagonists
Physiology
[SDV]Life Sciences [q-bio]
Thoracic Vein
030204 cardiovascular system & hematology
In Vitro Techniques
Pulmonary vein
Membrane Potentials
03 medical and health sciences
0302 clinical medicine
Catecholamines
Physiology (medical)
Internal medicine
medicine
Animals
Heart Atria
Atrium (heart)
Rats, Wistar
ComputingMilieux_MISCELLANEOUS
030304 developmental biology
Catecholaminergic
0303 health sciences
business.industry
Myocardium
Cardiac muscle
Atrial fibrillation
Heart
medicine.disease
Adrenergic Agonists
Rats
Electrophysiology
[SDV] Life Sciences [q-bio]
medicine.anatomical_structure
Pulmonary Veins
Circulatory system
Cardiology
Cardiology and Cardiovascular Medicine
business
Microelectrodes
Blood vessel
Subjects
Details
- Language :
- English
- ISSN :
- 03636135 and 15221539
- Database :
- OpenAIRE
- Journal :
- AJP-Heart and Circulatory Physiology, AJP-Heart and Circulatory Physiology, American Physiological Society, 2009, 297, pp.H102-H108
- Accession number :
- edsair.doi.dedup.....cc777526c6ed4a6d021efae57b06913c