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[Experimental study on elucidating pathogenesis of adriamycin induced cardiomyopathy (author's transl)]
Abstract:
For the determination of the pathophysiological mechanisms responsible for the adriamycin-induced cardiomyopathy we investigated the acute myocardial effects of this drug on contractile behavior in cultured embryonic ventricular cells in comparison to metabolic inhibitors, e.g., 2,4-dinitrophenol. There could be demonstrated a fall in contraction amplitude due to exposure to adriamycin, an increase in heart rate and the occurrence of "after-contractions". The fall in contraction could be explained by a decreased Ca-uptake by the sarcoplasmic reticulum (SR) and/or the mitochondria, leading to a rise in [Ca2+]i. This would tend to reduce spontaneous rate in pacemaker cells, to increase gK (conductance of potassium) and to influence the conduction. 10 microgram/ml adriamycin showed a 25% increment of K-flux above rest. A similar result was obtained by use of 10(-4) mmol/l 2,4-DNP which also caused cessation of spontaneous activity. This increment in K-flux, a parameter for K-permeability, might be caused by an increase in [Ca2+]i. The possible origin of this increment of [Ca2+]i might be of mitochondrial nature.l Thus an acute perturbance of mitochondrial function might give rise to [Ca2+]i, since mitochondria are known as Ca-buffering compartment. The pathophysiological mechanisms of the adriamycin cardiomyopathy therefore can be seen in the increase of [Ca2+]i.
Insights
Adriamycin causes heart damage by increasing intracellular calcium levels, affecting heart cell contraction and function. This mechanism, similar to metabolic inhibitors, highlights mitochondrial dysfunction in adriamycin cardiomyopathy.
Area of Science:
- Cardiology
- Cell Biology
- Pharmacology
Context:
- Adriamycin is a chemotherapy drug known to cause cardiotoxicity.
- The precise mechanisms underlying adriamycin-induced cardiomyopathy are not fully understood.
- Investigating cellular effects provides insight into drug-induced heart damage.
Purpose:
- To elucidate the pathophysiological mechanisms of adriamycin-induced cardiomyopathy.
- To compare the acute myocardial effects of adriamycin with metabolic inhibitors like 2,4-dinitrophenol.
- To analyze the impact of adriamycin on contractile behavior and ion flux in cultured embryonic ventricular cells.
Summary:
- Adriamycin exposure in cultured embryonic ventricular cells reduced contraction amplitude, increased heart rate, and caused after-contractions.
- This effect is linked to decreased calcium uptake by the sarcoplasmic reticulum and mitochondria, leading to elevated intracellular calcium ([Ca2+]i).
- Adriamycin (10 microgram/ml) increased potassium flux by 25%, similar to 2,4-dinitrophenol, suggesting increased potassium permeability possibly due to elevated [Ca2+]i originating from mitochondrial dysfunction.
Impact:
- Identifies elevated intracellular calcium as a key factor in adriamycin cardiomyopathy.
- Suggests mitochondrial dysfunction plays a critical role in adriamycin cardiotoxicity.
- Provides a cellular basis for understanding and potentially mitigating adriamycin's cardiac side effects.