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Cardiac sodium, potassium-adenosine triphosphatase as a possible site of adriamycin-induced cardiotoxicity
Abstract:
Adriamycin ws tested as a possible inhibitor of cardiac sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase). At concentrations of 10(-4) M and lower, Adriamycin had no effect upon either ouabain-sensitive (Na-K-ATPase) or ouabain-insensitive adenosine triphosphatase activity in homogenates and microsomal fractions of cardiac tissue from several different species. Adriamycin inhibited adenosine triphosphatase activity at a concentration of 10(-3) M, but this was due to the inhibition of ouabain-insensitive adenosine triphosphatase rather than to inhibition of Na-K-ATPase. Under no condition was an inhibition of Na-K-ATPase activity by Adriamycin observed. These conditions included preincubation of the enzyme with Adriamycin, chelation of Ca2+, addition of reduced nicotinamide adenine dinucleotide phosphate, and variation of buffer and pH. It was concluded that Na-K-ATPase is not a likely site of Adriamycin-induced cardiotoxicity.
Insights
Adriamycin does not inhibit cardiac sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase). This study suggests Na-K-ATPase is not a likely cause of Adriamycin-induced cardiotoxicity.
Area of Science:
- Biochemistry
- Cardiology
- Pharmacology
Background:
- Adriamycin is a chemotherapy drug with known cardiotoxicity.
- The mechanism of Adriamycin-induced cardiotoxicity is not fully understood.
- Cardiac sodium-potassium-activated adenosine triphosphatase (Na-K-ATPase) is crucial for heart function.
Purpose of the Study:
- To investigate whether Adriamycin inhibits cardiac Na-K-ATPase activity.
- To determine if Na-K-ATPase is a potential target for Adriamycin's cardiotoxic effects.
Main Methods:
- Enzyme activity assays were performed on cardiac tissue homogenates and microsomal fractions.
- Adriamycin was tested at various concentrations (10(-4) M and lower, and 10(-3) M).
- Specific conditions were varied, including preincubation, Ca2+ chelation, and buffer/pH adjustments.
Main Results:
- Adriamycin did not inhibit Na-K-ATPase activity at concentrations of 10(-4) M and lower.
- At 10(-3) M, Adriamycin inhibited general adenosine triphosphatase activity, but not specifically Na-K-ATPase.
- No inhibition of Na-K-ATPase was observed under any tested condition.
Conclusions:
- Cardiac Na-K-ATPase is unlikely to be the molecular target of Adriamycin-induced cardiotoxicity.
- The findings exclude Na-K-ATPase as a primary mediator of Adriamycin's adverse cardiac effects.