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[Mechanism of cellular toxicity induced by digitalis compounds. Study with ouabain]
Margarita del C Ramírez Ortega1, Vilma Maldonado Lagunas, Jorge Meléndez Zajgla
1Departamento de Farmacología, Instituto Nacional de Cardiología Ignacio Chávez, INCICH, Juan Badiano No. 1, Col. Sección XVI, Tlalpan, 14080 México, D. F. margarita0022@yahoo.com
Unlabelled:
The toxic effect of digitalis compounds at cell level produces an intracellular Ca2+ overload and a decrease in intracellular concentrations of K+. Since Ca2+ and K+ are critical modulators of life and death, the purpose of this study was to explore the cell death pathway activated through the ionic imbalance provoked by digitalis intoxication. We present results of cell toxicity in a study performed with ouabain acting on a HeLa cells culture and on guinea pig heart myocites under ouabain intoxication.
Results:
In tissue culture, ouabain produced inhibition of cell viability in a time and dose dependent manner. Through ethidium-bromide staining, nuclear condensation and fragmentation were observed. The electrophoretic analysis of nuclear DNA in agarose gel showed a degradation pattern characteristic of apoptosis. In histologic sections of guinea pig heart under ouabain intoxication (50-60% of lethal doses), in situ cell death was detected by in situ DNA TUNEL labeling. We conclude that the electrical and physiologic imbalance produced by toxic doses of ouabain activates mechanisms that cause cell death via apoptosis in heart myocites and fast growing cells.
Insights
Digitalis compounds like ouabain cause cell death by disrupting calcium and potassium balance. This study shows ouabain triggers apoptosis in heart cells and HeLa cells through ionic imbalance.
Area of Science:
- Cellular toxicology
- Cardiovascular research
- Molecular biology
Context:
- Digitalis compounds are widely used for heart conditions but can be toxic.
- Cellular ion homeostasis, particularly Ca2+ and K+, is crucial for cell survival.
- Understanding digitalis toxicity mechanisms is vital for patient safety and drug development.
Purpose:
- To investigate the cell death pathway activated by digitalis-induced ionic imbalance.
- To explore the effects of ouabain on cell viability and apoptosis.
- To determine if digitalis intoxication induces apoptosis in cardiac myocytes and other cell types.
Summary:
- Ouabain exposure inhibited HeLa cell viability in a dose- and time-dependent manner.
- Ethidium bromide staining revealed nuclear condensation and fragmentation, indicative of apoptosis.
- Agarose gel electrophoresis of DNA confirmed apoptotic DNA degradation patterns.
- In situ DNA TUNEL labeling detected cell death in guinea pig heart myocytes intoxicated with ouabain.
Impact:
- Demonstrates that toxic doses of ouabain induce apoptosis in heart myocytes and fast-growing cells.
- Highlights the role of ionic imbalance (Ca2+ overload, K+ decrease) in mediating digitalis-induced cell death.
- Provides insights into the molecular mechanisms of digitalis cardiotoxicity, potentially informing therapeutic strategies.