Shape change of blood platelets brought about by myelin basic protein and other basic polypeptides

Area of Science:

• Biochemistry
• Cell Biology
• Neuroscience

Background:

• Basic proteins and polypeptides (BPP) are known to induce neuronal depolarization in the central nervous system.
• Myelin basic protein (MBP) is a key example of such BPP.

Purpose of the Study:

• To investigate the effect of BPP on blood platelets.
• To determine if platelets can serve as a model for neuronal responses to BPP.

Main Methods:

• Exposure of platelets from various species, including humans, to different BPP.
• Monitoring for shape change, aggregation, 5-hydroxytryptamine release, and cyclic nucleotide levels.
• Testing the effect of heparin and other antagonists on BPP-induced platelet shape change.

Main Results:

• BPP, including polyornithine (M.W. 40,000), polylysine, and protamine, induced a platelet shape change.
• This shape change was not associated with platelet aggregation, 5-hydroxytryptamine release, or altered cyclic nucleotide levels.
• Heparin inhibited the polyornithine-induced shape change, while other antagonists had no effect.
• Lower molecular weight polyornithine and other basic substances did not induce platelet shape change.

Conclusions:

• Platelet shape change is a sensitive and simple assay for detecting BPP that cause functional changes in mammalian cells.
• Platelets can be utilized as models to study the effects of BPP on plasma membranes, similar to their action on neurons.