The affinity of narcotic agents for interfacial films

Relationship between potency and boiling point of general anesthetics: a thermodynamic consideration

The most important group of nonspecific drugs is that of the general anesthetics. These nonspecific compounds vary greatly in structure, from noble gases such as Ar or Xe to complex steroids. Since the development of clinical anesthesia over a century ago, there has been a vast amount of research and speculation concerning the mechanism of action of general anesthetics. Despite these efforts, the exact mechanism remains unknown. Many theories of narcosis do not explain how unconsciousness is produced at a molecular level, but instead relate some physicochemical property of anesthetic agents to their anesthetic potencies. In this paper, we address some of those physicochemical properties, with more emphasis on correlating the anesthetic potency of volatile anesthetics to their boiling points based on thermodynamic principles.

Diving physiology and pathophysiology

Divers have worked at 500 m depth in the sea and have reached 700 m in simulated chamber dives. A prerequisite for this has been extensive physiological studies of the body's reactions to pressure and pressure changes. This paper reviews such physiological and pathophysiological studies with emphasis on recent developments.

Comparative effects of volatile anaesthetic agents and nitrous oxide on human leucocyte chemotaxis in vitro

Infection following surgery is not uncommon. Human leucocytes play a vital role in the body's defense against infection. In order to decrease perioperative morbidity and mortality from infection, it is important to define the comparative effects of different anaesthetic agents on the leucocyte function. Therefore, the effect of equipotent concentrations (MAC 1) of isoflurane, enflurane, halothane, methoxyflurane and 70 per cent nitrous oxide, on the leucocyte chemotactic migration was investigated in vitro. The chemotactic migration of neutrophils and monocytes, with and without equilibration with MAC 1 concentrations of different volatile anaesthetics and 70 per cent nitrous oxide, was compared by using a modification of Boyden's method. Chemotactic migration of both cell types was unaffected by isoflurane, but a significant depression of chemotactic migration was observed with enflurane, halothane, methoxyflurane and nitrous oxide (p less than 0.05). The severity of depression of migration was maximal with nitrous oxide, followed by methoxyflurane, halothane and enflurane in order. It is concluded that equipotent concentrations of various anaesthetic agents produce different degrees of depression of leucocyte chemotactic migration in vitro.

Molecular mechanisms of general anaesthesia

Important constraints on possible molecular mechanisms of general anaesthesia are derived from a quantitative reappraisal of data on the potency of general anaesthetics on whole animals. Despite their popularity, theories that invoke lipids as the prime target do not look at all promising, and available data point much more plausibly to a direct effect on particularly sensitive proteins. Structural changes of proteins on binding general anaesthetics are probably small but may be sufficient to perturb normal function; alternatively, anaesthetics may compete with an endogenous ligand. The phenomenon of pressure reversal of anaesthesia may simply be due to anaesthetics being squeezed away from their target sites.

Chloral hydrate mediated inhibition of cell division and of proton synthesis

Chloral hydrate (along with other anaesthetics and hypnotics) is an inhibitor of cell division. We have shown that chloral hydrate is also an inhibitor of protein synthesis. This inhibition is unlikely to be a result of either of the disruption of cell division or of interference with the function of microtubules. The ability of chloral hydrate to inhibit cell division may result from its ability to inhibit protein synthesis.

Action of anionic and cationic nerve-blocking agents: experiment and interpretation

Barbiturates and anesthetics similar to procaine bind to phospholipids in vitro. The former increase the binding of calciumn to the phospholipids; the latter decrease it. The data can be correlated with the effects of these drugs Otl peripheral nerve. The nonpolar portion of the narcotic agents may lie between the lipid chains of the membrane, with the charged region in close approximation to the polar heads of the phospholipids.

Electrostatic aspects of physical adsorption: implications for molecular sieves and gaseous anesthesia

The equations of electrostatics are applied to the adsorption of gases on molecular sieves; separations on sieves are caused not by the size of molecules but by electrostatic forces between the gases and the strong electric fields of the sieves. Electrostatic interactions can also explain the phenomenon of general anesthesia.

Membrane Permeability: Monolayer Relationships

A model of permeation of living membranes is proposed in which penetration by polar molecules takes place through islands composed of limited numbers of lipoidal molecules in a state comparable to that of certain compressed monolayers. These islands are visualized as scattered within a rigid, relatively impervious matrix. Relationships for penetration of monolayers by gases have been applied to this membrane model. Calculations on this basis demonstrate that the permeabilities relative to water are described at least as well by this model as by that assuming rigid pores of 4.25 A radius.