Mechanism of the phenomenon of fixation of acetylcholine by human blood in vitro

Summary

The phenomenon of acetylcholine binding with human blood was described by the authors in 1961. At low temperature the blood of a healthy individual is found to bind within 24 h 29–13% of an added 1 ml acetylcholine in a 10⁻⁹ dilution. The amount of acetylcholine mixed by the blood of patients suffering from various diseases varied within a wide range. The highest degree of binding (up to 100%) was noted in myasthenia and in some forms of diencephalic lesions. The binding phenomenon probably reflects the state (reactivity and tone) of the parasympathetic nervous system.

A study of the mechanisms of the phenomenon demonstrated that the binding capacity was confined to erthrocytes. Blood plasma contains a factor regulating the binding phenomenon. Hemolyzed erythrocytes fail to bind acetylcholine. Addition of potassium ions to the blood decreases its binding properties, whereas addition of calcium ions binding.