Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Schillinger, W; Ohler, A; Emami, S; Müller, F; Christians, C; Janssen, PM; Kögler, H; Teucher, N; Pieske, B; Seidler, T; Hasenfuss, G.
The functional effect of adenoviral Na+/Ca2+ exchanger overexpression in rabbit myocytes depends on the activity of the Na+/K+-ATPase.
Cardiovasc Res. 2003; 57(4):996-1003
Doi: 10.1016/S0008-6363(02)00829-5
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- Co-Autor*innen der Med Uni Graz
- Pieske Burkert Mathias
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- Abstract:
- OBJECTIVES: The functional consequences of Na+/Ca2+ exchanger (NCX) overexpression in heart failure have been controversially discussed. NCX function strongly depends on intracellular sodium which has been shown to be increased in heart failure. METHODS AND RESULTS: We investigated the Na+/K+-ATPase (NKA) inhibitor ouabain (0.5-16 micromol/l) in electrically stimulated, isotonically contracting adult rabbit cardiocytes overexpressing NCX after adenoviral gene transfer (Ad-NCX-GFP, 48 h culture time). Myocytes transfected with adenovirus encoding for green fluorescent protein (Ad-GFP) served as a control. Contractions were analyzed by video-edge detection. In the Ad-NCX-GFP group, the maximum inotropic response was significantly reduced by 50.7% (P<0.05). This was a result of an enhanced susceptibility to contracture after exposure to the drug (median concentration (25-75%): 4 (4-8) vs. 8 (6-16) micromol/l, P<0.05). When analyzing relaxation before contracture, the maximum relaxation velocity was reduced (0.15+/-0.04 vs. 0.27+/-0.04 microm/s, P<0.05) and the time from peak shortening to 90% of relaxation was increased (298+/-39 vs. 185+/-15 ms, P<0.05). No differences in systolic and diastolic parameters were observed with the Na+ channel modulator BDF9198 (1 micromol/l). CONCLUSIONS: Inhibition of NKA by ouabain induces a combined diastolic and systolic dysfunction in NCX overexpressing rabbit myocytes. This may be the consequence of cytoplasmic Ca2+ overload due to inhibition of forward mode or induction of reverse mode Na+/Ca2+ exchange. In end-stage failing human myocardium and during digitalis treatment this mechanism may be of major importance.
- Find related publications in this database (using NLM MeSH Indexing)
- Adenoviridae - genetics
- Animals - genetics
- Cardiotonic Agents - pharmacology
- Cells, Cultured - pharmacology
- Enzyme Inhibitors - pharmacology
- Genetic Vectors - pharmacology
- Myocardial Contraction - drug effects
- Myocytes, Cardiac - metabolism
- Na(+)-K(+)-Exchanging ATPase - antagonists and inhibitors
- Ouabain - pharmacology
- Rabbits - pharmacology
- Sodium Channels - drug effects
- Sodium-Calcium Exchanger - genetics
- Transfection - genetics
- Find related publications in this database (Keywords)
- calcium (cellular)
- contractile function
- heart failure
- Na/Ca-exchanger
- Na/K-pump