The effect of ethanol on the passive Ca permeability of human red cell ghosts measured by means of arsenazo III

Influence of age on the stability of human erythrocyte membranes

This work evaluated the dependence of erythrocyte membrane stability on age, temperature (26, 32, 37, 42 and 47 degrees C), nutritional status, red cell count, red cell distribution width (RDW) and mean corpuscular volume (MCV) in human females (n = 67, 20-94 years). Erythrocyte membrane resistance to hypotonic lysis was expressed as the NaCl concentration (H(50)) capable of promoting 50% haemolysis. A nutritional evaluation was performed using the Mini Nutritional Assessment (MNA) instrument, which showed that 76.1% of the study group were well nourished and 23.9% were at risk of malnutrition. H(50) demonstrated a negative correlation with age at all temperatures. H(50) showed no correlation with either MNA scores or with any haematological indices. The power and significance of the correlations improved when we censored from the analyses those individuals at risk of malnutrition. The thermal dependencies lines for H(50) demonstrated higher values for females 20-39 years of age compared with those more than 60 years of age. These results suggest that erythrocyte resistance to hypotonicity (erythrocyte membrane stability), increased with age of study volunteers. This increased stability was more pronounced among well-nourished individuals.

Acute effect of ethanol on lens cation homeostasis

This study examined the effect of ethanol on the calcium homeostasis of the bovine lens. After acute exposure of the whole lens to physiologically related ethanol concentration, the calcium content of the lens cortex increased from 0.345 +/- 0.075 to 0.476 +/- 0.047 micromol/g (p < 0.05). In contrast, other cation levels such as sodium, potassium, and magnesium did not change. In the study of the lens calcium transport, ethanol caused an increase in the calcium permeability of the lens lipid membrane by about 12% at 30 mM ethanol. Ethanol did not alter the calcium pump activity at ethanol concentration up to 400 mM. Above 600 mM ethanol, the calcium pump was almost completely inhibited. It has been suggested that moderate to heavy alcohol consumption is a risk factor for cataracts. This study indicates that acute ethanol exposure can cause a loss in the lens calcium homeostasis, which maybe one of the cellular mechanisms to contribute to the cataract development in the alcoholic individual.

Increase of the anion and proton permeability of Saccharomyces carlsbergensis plasmalemma by n-alcohols as a possible cause of its de-energization

The effect of n-alcohols on ATP-dependent generation of delta pH and Em across the plasma membrane vesicles of the yeast Saccharomyces carlsbergensis was investigated. The alcohols were shown to collapse delta pH and Em in the order C2 less than C3 less than C4 less than C5 less than or equal to C6 greater than or equal to C7 greater than C8 greater than C11, the dissipation of Em being more pronounced. Inhibition of the plasmalemma H(+)-ATPase was insignificant; at low alcohol concentrations its activity even increased. The basic reason for the toxic effect of the alcohols on the yeast cells was suggested to be due to the increase in the anion and proton permeability of the plasma membrane. Mg2+ partially prevented the increase in the plasmalemma ion permeability by the alcohols investigated.

Acute hypocalcemic effect of ethanol in dogs

Ethanol has been shown to reduce serum calcium in multiple animal studies. However, in human studies done using lower doses of alcohol, only inconclusive results have been obtained. This study was undertaken to evaluate the effects of varying doses of oral ethanol on total serum calcium. Fifteen adult mongrel dogs (17-25 kg) were divided into three groups which differed in the dosage of ethanol given. Group I animals received 0.5 g/kg of ethanol; Group II, 1.0 g/kg ethanol; and Group III, 2.0 g/kg of ethanol. Venous blood was sampled for estimation of concentrations of total serum calcium and ethanol. In the animals in Group I, serum calcium levels were unchanged by the ethanol. In both Groups II and III, significant reductions in serum calcium were demonstrated, which occurred within 5 min of intoxication. The mean decrease in serum calcium in Group III animals was significantly greater than that in either Group I and II. We conclude that the rapid hypocalcemic effect requires a threshold amount of ethanol before it becomes chemically evident. This critical value in dogs approximated 1 g/kg which results in a mean peak serum alcohol concentration of 117 +/- 6 mg/dl.

Increases in internal Ca2+ and decreases in internal H+ are induced by general anesthetics in squid axons

Squid axons were injected with arsenazo III and treated with sea water containing compounds usually classified as general anesthetics, (pentanol-decanol and a variety of hydrocarbons and their derivatives). Such treatment led to an increase in absorbance by arsenazo III at wavelengths sensitive to [Ca]i. The effect was independent of the presence or absence of Ca++ in sea water and it was not modified by substances that release Ca from internal stores. The effect was easily reversible. In axons injected with phenol red or impaled with a glass electrode sensitive to H+, a similar treatment led to an alkalinization that was also readily reversible. Both Ca release and the change to an alkaline pH had identical time courses. The dose required for action by all of the chemical agents studied could be predicted from a knowledge of their fractional saturation in sea water, i.e. from their thermodynamic activity. For compounds with 8-10 carbon atoms, Ca-release effects can occur at concentration less than those necessary to block either conduction or Na/Ca exchange. A special chemical agent was octylamine, which induced a marked rise in pHi and in addition its nonionic form produced the typical Ca release associated with general anesthetics.