William C. Holland

Effects of temperature, Na and K concentration and quinidine on transmembrane flux of K42 and incidence of atrial fibrillation.

Experimental data is presented and discussed on the effects of temperature, K and Na concentration, and quinidine on transmembrane ion fluxes and the incidence of fibrillation in isolated rabbit atria.

Fibrillation and Potassium Influx

Absolute influx and efflux of potassium-42 have been measured in isolated rabbit atria during acetylcholine-induced fibrillation. The efflux of potassium was increased three to four times; influx was not changed. The data are interpreted as indicating that an inhibition of active K uptake is not involved in the initiation of fibrillation, and that the process results from a marked increase in Na permeability.

The synthesis of acetylcholine by human erythrocytes.

Abstract Human erythrocytes synthesize acetylcholine. Implications of these findings are discussed.

Acetyicholine and Electrolyte Metabolism in the Various Chambers of the Frog and Turtle Heart

Evidence has accumulated suggesting acetylcholine may he involved in initiation of the heart heat. Acetylcholine and electrolyte metabolism in the various chambers of the heart have been studied. The area of highest intrinsic rhythm (sinus) contained greater amounts of acetylcholine equivalents, true cholinesterase, choline acetylase and sodium; all of these decreasing in amount in areas of lower intrinsie rhythm. It is concluded that intrinsic rhythm may he directly correlated with overall acetylcholine metabolism and sodium content and inversely related to overall energy metabolism and potassium concentration.

Studies on permeability. VI. Increased permeability of dog erythrocytes caused by cholinesterase inhibitors

Abstract 1. 1. The effects of several inhibitors of cholinesterase activity on the permeability of dog erythrocytes have been studied. The following drugs were investigated: physostigmine, prostigmine, caffeine, and choline. 2. 2. Permeability effects were noted only with drugs in concentrations that produced 50% or more inhibition of cholinesterase activity. 3. 3. Acetyl choline in concentrations of 10 −2 -10 −5 M produced significant increases in resistance of dog erythrocytes to hemolysis, the magnitude of the effects varying with the concentration of drug.

Effect of the D- and L-isomers of Isoamidone on the Permeability of Dog Erythrocytes.

Summary The theory that the acetyl-choline-cholinesterase system is concerned with membrane permeability is further substantiated by the finding that the L-isomer of isoamidone which has a greater inhibitory action on cholinesterase than has the D-isomer also changes permeability of dog erythrocytes to a different degree than does the D-isomer. The conditions under which the L has a greater effect than the D-isomer on permeability are a medium containing a high proportion of K ions relative to Na ions.

Application of the free electron model to the study of light absorption of enzyme-substrate complexe

Summary The free-electron model as developed by Kuhnm Bayliss, and others is briefly discussed. The model appears to be particularly well suited for the interpretation of spectral shifts that occur on formation of enzymesubstrate compounds.