[Temperature dependence of the acetylcholinesterase activity in synaptic membranes of the rat brain].

The temperature dependence (5-40 degrees C) of the acetylcholinesterase activity in synaptic membranes of the rat brain at different substrate concentrations was studied. At low substrate concentrations, the Arrhenius plot has two linear sections. At high concentration, there is one linear section throughout the temperature range.

[The effect of hypothermia on kinetic characteristics of the rat brain synaptic membrane Na,K-ATPase].

The effect of profound hypothermia (acute or prolonged) on Km for ATP, Vm and strophanthine K affinity to Na,K-ATPase in the rat brain synaptosomal membranes was investigated. The temperature dependence of Na,K-ATPase activity in temperature range 5-40 degrees C was also studied. Hypothermia decreases Km and Vm, and increases affinity of strophanthine K to the enzyme.

Effect of hypothermia on kinetic characteristics of acetylcholine esterase in rat erythrocyte membranes.

We studied kinetic and thermodynamic characteristics of acetylcholine esterase in rat erythrocyte membrane after whole-body hypothermia (20 degrees C) of different duration. Hypothermia increased the degree of substrate inhibition for acetylcholine esterase, maximum rate, and Michaelis constant. The temperature dependence of acetylcholine esterase activity remained practically unchanged.

[Effect of hypothermia on Na(+)-K(+)-ATPase activity and hemoglobin binding in the rat erythrocyte membranes].

The activity of Na+/K(+)-ATPase and hemoglobin binding in membranes of rat erythrocytes during hypothermia (20 degrees C) was studied. Hypothermia causes an increase in hemoglobin binding and a decrease in Na+/K(+)-ATPase activity. It was found in in vitro experiments that the addition of hemoglobin to the membranes does not affect the Na+/K(+)-ATPase activity in control animals and decreases the activity of the enzyme in hypothermia.