Effects of T3, T4 and methyltiouracile short-term treatments on plasma and liver lipid levels in rats (author's transl)

The effects of short-term administration of thyroid hormones (T3 and T4) and methyltiouracile (MTU) on liver and plasma lipid levels in female rats have been comparatively studied T3 increases the levels of all the studied liver lipids and decreases the plasma lipids. T4 produces smaller and even, in some cases (liver triglycerides and cholesterol esters), opposite effects. The administration of MTU produces, in general, opposite effects to T3 and T4.     

Kinetics of renin reaction in rat plasma (author's transl)]

Important kinetic aspects of renin reaction were studied in order to evaluate the parameters that regulate the formation rate of angiotensin I. This rate decreased throughout the incubation period of normal rat plasma and it showed a linear increase when plasma was incubated with renin-substrate. When renin was added to normal rat plasma a plateau in the angiotensin I formation rate occurred after 4-6 hours. When plasma samples containing increasing amounts of renin-substrate were incubated, the velocity of their reaction increased in proportion to the renin-substrate concentration. Under these incubation conditions, the reaction between endogenous renin and renin-substrate in normal rat plasma, proved to be a first kinetic order with respect to the substrate.     

Effect of mexiletine on glucose and oxygen uptake in rat brain, liver and myocardial tissue in vitro (author's transl)

The effect of mexiletine on oxygen and glucose consumption was studied both in homogenate and slices of brain, liver and myocardium of Wistar rats. Oxygen consumption was detected by means of Warburg's manometric techniques, and glucose utilization by the enzymatic method of glucose oxidase. Whilst glucose uptake was not modified in any of the studied preparations, mexiletine promoted a significant increase of oxygen consumption in the homogenized slices, and an inhibition in the intact tissue.     

Purine catabolism in rat brain (author's transl)

In soluble rat brain fraction, the specific activities of purine nucleoside phosphorylase, guanine deaminase, 5'Nucleotidase and adenosine deaminase, decrease in their mentioned order. A kinetic parameter comparison between these enzymes shows that 5'Nucleotidase with AMP has the lowest KM and the greatest Vmax values, while purine nucleoside phosphorylase has its lowest KM and its greatest Vmax values with guanosine and with inosine, respectively. The enzymes activity is not modified by the metabolic intermediates differently from their own reaction products which behave as competitive inhibitors.