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Digitalis-like biological activity in rat cerebellum
Biochemistry and Cell Biology = Biochimie Et Biologie Cellulaire
|October 1, 1986
Summary
Researchers found a substance in rat cerebellum that acts like digitalis. This endogenous digitalis-like principle inhibits Na,K-ATPase activity and has positive inotropic effects.
Area of Science:
- Neurochemistry
- Pharmacology
- Physiology
Background:
- The brain contains endogenous compounds that can influence cardiovascular function.
- Synaptosomes are crucial for neurotransmitter uptake and ion transport.
- Ouabain is a well-known cardiac glycoside that inhibits Na,K-ATPase.
Purpose of the Study:
- To investigate the presence and characteristics of a potential endogenous digitalis-like factor in rat cerebellum.
- To determine if this factor affects synaptosomal Na,K-ATPase activity and cardiac contractility.
Main Methods:
- Preparation of cytosolic fraction from rat cerebellum.
- Assay of Na,K-ATPase activity in rat brain synaptosomes.
- Measurement of [3H]ouabain binding to synaptosomes.
- Assessment of positive inotropic effects on guinea pig atrial strips.
- Evaluation of factor's sensitivity to heat and proteolytic agents, and effect of Mg2+.
Main Results:
- The rat cerebellar cytosolic fraction inhibited synaptosomal Na,K-ATPase activity.
- The factor competed with [3H]ouabain binding, indicating a similar binding site.
- The factor induced positive inotropy in atrial strips, similar to digitalis glycosides.
- Inhibitory activity was partially thermolabile and reduced by proteolysis.
- Activity was augmented by increased Mg2+ concentrations.
Conclusions:
- Rat cerebellum contains an endogenous ouabain-like principle.
- This principle exhibits characteristics suggesting a regulatory role in cellular processes.
- The findings suggest a potential endogenous digitalis-like substance in the brain with physiological implications.