Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes
| Autor: | Hans Gesser, Lluis Tort, Cristina E. Molina, Leif Hove-Madsen, Anna Llach |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Atropine
medicine.medical_specialty Patch-Clamp Techniques Potassium Channels Physiology Heart Ventricles Action Potentials Cell Separation Muscarinic Antagonists In Vitro Techniques Membrane Potentials TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY Physiology (medical) Internal medicine medicine Animals Ventricular Function Myocyte Myocytes Cardiac Heart Atria Patch clamp Potassium Channels Inwardly Rectifying Membrane potential biology Chemistry biology.organism_classification Resting potential Acetylcholine Potassium channel Trout Endocrinology Oncorhynchus mykiss cardiovascular system Biophysics Rainbow trout Microelectrodes medicine.drug |
| Zdroj: | Molina, C E, Gesser, H, Llach, A, Tort, L & Hove-Madsen, L 2007, ' Modulation of membrane potential by an acetylcholine-activated potassium current in trout atrial myocytes ', Am. J. Physiol. Regul. Integr. Comp. Physiol., vol. 292, pp. R388-R395 . https://doi.org/10.1152/ajpregu.00499.2005 |
| ISSN: | 1522-1490 0363-6119 |
| DOI: | 10.1152/ajpregu.00499.2005 |
| Popis: | Application of the current-clamp technique in rainbow trout atrial myocytes has yielded resting membrane potentials that are incompatible with normal atrial function. To investigate this paradox, we recorded the whole membrane current (Im) and compared membrane potentials recorded in isolated cardiac myocytes and multicellular preparations. Atrial tissue and ventricular myocytes had stable resting potentials of -87 ± 2 mV and -83.9 ± 0.4 mV, respectively. In contrast, 50 out of 59 atrial myocytes had unstable depolarized membrane potentials that were sensitive to the holding current. We hypothesized that this is at least partly due to a small slope conductance of Im around the resting membrane potential in atrial myocytes. In accordance with this hypothesis, the slope conductance of Im was about sevenfold smaller in atrial than in ventricular myocytes. Interestingly, ACh increased Im at -120 mV from 4.3 pA/pF to 27 pA/pF with an EC50 of 45 nM in atrial myocytes. Moreover, 3 nM ACh increased the slope conductance of Im fourfold, shifted its reversal potential from -78 ± 3 to -84 ± 3 mV, and stabilized the resting membrane potential at -92 ± 4 mV. ACh also shortened the action potential in both atrial myocytes and tissue, and this effect was antagonized by atropine. When applied alone, atropine prolonged the action potential in atrial tissue but had no effect on membrane potential, action potential, or Im in isolated atrial myocytes. This suggests that ACh-mediated activation of an inwardly rectifying K+ current can modulate the membrane potential in the trout atrial myocytes and stabilize the resting membrane potential. teleost heart; IK,ACh; cholinergic modulation; action potential |
| Databáze: | OpenAIRE |
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