Abstract
Intracellular Na+ concentration ([Na+]i) is very important in modulating the contractile and electrical activity of the heart. Upon electrical excitation of the myocardium, voltage-dependent Na + channels open, triggering the upstroke of the action potential (AP). During the AP, Ca2+ enters the myocytes via L-type Ca 2+ channels. This triggers Ca2+ release from the sarcoplasmic reticulum (SR) and thus activates contraction. Relaxation occurs when cytosolic Ca2+ declines, mainly due to re-uptake into the SR via SR Ca2+-ATPase and extrusion from the cell via the Na +/Ca2+ exchanger (NCX). NCX extrudes one Ca2+ ion in exchange for three Na+ ions and its activity is critically regulated by [Na+]i. Thus, via NCX, [Na+] i is centrally involved in the regulation of intracellular [Ca 2+] and contractility. Na+ brought in by Na+ channels, NCX and other Na+ entry pathways is extruded by the Na +/K+ pump (NKA) to keep [Na+]i low. NKA is regulated by phospholemman, a small sarcolemmal protein that associates with NKA. Unphosphorylated phospholemman inhibits NKA by decreasing the pump affinity for internal Na+ and this inhibition is relieved upon phosphorylation. Here we discuss the main characteristics of the Na+ transport pathways in cardiac myocytes and their physiological and pathophysiological relevance.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 215-221 |
| Number of pages | 7 |
| Journal | IUBMB Life |
| Volume | 61 |
| Issue number | 3 |
| DOIs | |
| State | Published - 2009 |
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Keywords
- Na channels
- Na/Ca exchanger
- Na/K ATPase
- Phospholemman
ASJC Scopus subject areas
- Biochemistry
- Cell Biology
- Clinical Biochemistry
- Molecular Biology
- Genetics
Cite this
Na+ transport in cardiac myocytes; implications for excitation-contraction coupling. / Bers, Donald M; Despa, Sanda.
In: IUBMB Life, Vol. 61, No. 3, 2009, p. 215-221.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Na+ transport in cardiac myocytes; implications for excitation-contraction coupling
AU - Bers, Donald M
AU - Despa, Sanda
PY - 2009
Y1 - 2009
N2 - Intracellular Na+ concentration ([Na+]i) is very important in modulating the contractile and electrical activity of the heart. Upon electrical excitation of the myocardium, voltage-dependent Na + channels open, triggering the upstroke of the action potential (AP). During the AP, Ca2+ enters the myocytes via L-type Ca 2+ channels. This triggers Ca2+ release from the sarcoplasmic reticulum (SR) and thus activates contraction. Relaxation occurs when cytosolic Ca2+ declines, mainly due to re-uptake into the SR via SR Ca2+-ATPase and extrusion from the cell via the Na +/Ca2+ exchanger (NCX). NCX extrudes one Ca2+ ion in exchange for three Na+ ions and its activity is critically regulated by [Na+]i. Thus, via NCX, [Na+] i is centrally involved in the regulation of intracellular [Ca 2+] and contractility. Na+ brought in by Na+ channels, NCX and other Na+ entry pathways is extruded by the Na +/K+ pump (NKA) to keep [Na+]i low. NKA is regulated by phospholemman, a small sarcolemmal protein that associates with NKA. Unphosphorylated phospholemman inhibits NKA by decreasing the pump affinity for internal Na+ and this inhibition is relieved upon phosphorylation. Here we discuss the main characteristics of the Na+ transport pathways in cardiac myocytes and their physiological and pathophysiological relevance.
AB - Intracellular Na+ concentration ([Na+]i) is very important in modulating the contractile and electrical activity of the heart. Upon electrical excitation of the myocardium, voltage-dependent Na + channels open, triggering the upstroke of the action potential (AP). During the AP, Ca2+ enters the myocytes via L-type Ca 2+ channels. This triggers Ca2+ release from the sarcoplasmic reticulum (SR) and thus activates contraction. Relaxation occurs when cytosolic Ca2+ declines, mainly due to re-uptake into the SR via SR Ca2+-ATPase and extrusion from the cell via the Na +/Ca2+ exchanger (NCX). NCX extrudes one Ca2+ ion in exchange for three Na+ ions and its activity is critically regulated by [Na+]i. Thus, via NCX, [Na+] i is centrally involved in the regulation of intracellular [Ca 2+] and contractility. Na+ brought in by Na+ channels, NCX and other Na+ entry pathways is extruded by the Na +/K+ pump (NKA) to keep [Na+]i low. NKA is regulated by phospholemman, a small sarcolemmal protein that associates with NKA. Unphosphorylated phospholemman inhibits NKA by decreasing the pump affinity for internal Na+ and this inhibition is relieved upon phosphorylation. Here we discuss the main characteristics of the Na+ transport pathways in cardiac myocytes and their physiological and pathophysiological relevance.
KW - Na channels
KW - Na/Ca exchanger
KW - Na/K ATPase
KW - Phospholemman
UR - http://www.scopus.com/inward/record.url?scp=77951030863&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77951030863&partnerID=8YFLogxK
U2 - 10.1002/iub.163
DO - 10.1002/iub.163
M3 - Article
VL - 61
SP - 215
EP - 221
JO - IUBMB Life
JF - IUBMB Life
SN - 1521-6543
IS - 3
ER -