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Endothelial modulation of the vascular sodium pump
C F Sánchez-Ferrer1, A Ponte, M A Casado
1Departamento de Farmacología y Terapéutica, Facultad de Medicina de la Universidad Autónoma de Madrid, Spain.
Journal of Cardiovascular Pharmacology
|January 1, 1993
Summary
The endothelium inhibits ouabain-induced vasoconstriction via a diffusible factor, but this protective effect diminishes with age. This finding is crucial for understanding vascular smooth muscle function and aging.
Area of Science:
- Cardiovascular Physiology
- Endothelial Biology
- Pharmacology
Background:
- Ouabain, a cardiac glycoside, affects vascular smooth muscle contractility.
- The endothelium plays a role in regulating vascular tone.
- Age-related changes in vascular function are not fully understood.
Purpose of the Study:
- To investigate the role of the endothelium in modulating ouabain's effects on vascular smooth muscle.
- To determine the nature of the endothelial factor involved.
- To examine age-dependent changes in endothelial modulation of ouabain's effects.
Main Methods:
- Isolated human placental vessels, reserpinized guinea pig carotid arteries, and Wistar-Kyoto rat aortas of various ages were used.
- Experiments involved endothelium removal and assessment of ouabain-evoked contractions.
- Sodium-pump activity was measured using 86Rb+ uptake.
- Bioassays were conducted to identify potential endothelial factors.
Main Results:
- Endothelium removal enhanced ouabain-induced contractions in human and guinea pig vessels.
- Endothelial modulation was independent of nitric oxide, prostaglandins, and leukotrienes.
- Age-dependent effects were observed in rat aortas, with modulation lost in older animals.
- Endothelium removal reduced 86Rb+ uptake, indicating an effect on sodium-pump activity.
Conclusions:
- The endothelium exerts an inhibitory modulation on ouabain-induced vasoconstriction through a diffusible factor.
- This factor's mechanism may involve stimulating sodium-pump activity or antagonizing ouabain's inhibition.
- Endothelial modulation of ouabain effects is lost in aged vascular tissue.