The rôle of lipoids and particularly lecithin in narcosis

Abstract

Following the discovery of anesthetic properties of ether by Jackson and Morton in 1846, numerous theories appeared in the literature which aimed to explain this important phenomenon. Of these the well-known Meyer-Overton theory is the only one that has survived the test of time. It reads as follows: “The narcotizing substance enters into a loose physio-chemical combination with the lipoids of the cells, perhaps with the lecithin, and in doing so changes their normal relationship to other cell constituents through which an inhibition of the entire cell chemism results.” Evidently this theory casts no light upon the nature of the alterations in cell chemism that follow. It remained for Verworn, Mansfeld, Bücher and Heaton not only to demonstrate the nature of these changes in cell chemism but also to show that the anesthetic state itself is in all probability dependent upon these alterations.

Reicher, who demonstrated the constant presence of lipoidemia after narcosis, explained this as being a protective mechanism; the lipoid molecules acting as amboceptors uniting with anesthetic and thus protecting the more vitally important brain lipoids. Nerking attempted to prove this experimentally by injecting various quantities of a 1 to 20 per cent. lecithin emulsion in normal salt solution intravenously, intraperitoneally, intraspinally or subcutaneously in animals which had been narcotized or were about to be anesthetized and claimed to have shown that “The injection of lecithin has an undoubted influence upon the duration and after effects of anesthesia in that it shortens its duration, brings about a more rapid return to consciousness and eliminates unpleasant after effects.”

A careful analysis of Nerking's work shows it to be scarcely worthy of serious consideration, owing to its lack of exactness in the dosage of the narcotic and the indefiniteness of the criteria used.