Aging and food restriction: effect on lipids of cerebral cortex.

In experimental animals dietary restriction reduces the body weight increase due to aging, increases longevity and delays the onset of age-related physiological deterioration, including age-related changes in serum lipids. Little is known about the influence of food restriction on brain lipids, whose concentration and composition have been shown to change with age. We studied whether some biochemical and biophysical parameters of rat brain membranes, known to be modified with age, were affected by a diet low in calories, in which 50% of lipids and 35% of carbohydrates have been replaced by fibers. The diet was started at weaning and maintained throughout the animal's entire life span. Animals fed the low calorie diet survived longer and gained less body weight than standard diet fed rats. Age-related increases in microviscosity, cholesterol/phospholipid and sphingomyelin/phosphatidylcholine ratios were reduced or restored to the levels of young animals in cortex membranes of 32 old rats fed the low calorie diet, while the age-related increase in mono- to polyunsaturated fatty acid ratios in phospholipids was further raised. In conclusion we have shown that a diet low in calories and high in fibers affects lipid composition in the rat brain, in a direction opposite to that normally believed to reduce age-related deterioration of brain functions.

Tissue distribution of propafenone in the rat after intravenous administration.

Tissue distribution of propafenone has been studied in the rat. Measurement of propafenone was made in several tissues: plasma, heart, kidney, lung, liver, muscle, fat and brain, after i.v. administration of 2 mg/kg of the drug. The plasma propafenone kinetics profile can be described by a two-compartmental model. The pharmacokinetic parameters, derived from plasma levels, showed a t1/2 beta of 55.4 min, the central Vd/kg of 2.4 ml/kg, the Cl of 62.8 ml/min.kg and the AUC0-oo of 31.6 micrograms.min/ml. The analysis of the propafenone tissue distribution showed the highest concentration of drug in the lung, followed by the heart and kidneys. A significant concentration was found in brain, muscle and adipose tissue, with concentration ratios (tissue/plasma) above 1. The half-life values obtained for individual organs and tissues are similar to those obtained in plasma, around 1 h. In the post-distributive phase, plasma and tissue concentrations decline in parallel.

Effect of ambroxol on rabbit eustachian tube surfactant.

The effect of ambroxol administration on phospholipid and phosphatidyl-choline contents of rabbit eustachian tube and lung washings and on [14C]-choline incorporation by rabbit eustachian tube and lung tissue has been studied. Despite minor differences, the drug exerts the same activating effect in both locations. The results add a further piece of evidence to the several similarities existing between the lung surfactant and the surface-active substances present on the eustachian tube.

Disaturated phosphatidylcholine in rabbit eustachian tube surfactant.

A chemical analysis of phospholipids in rabbit Eustachian tube and in its lavages shows phosphatidylcholine (PC) as being the predominating compound, followed by sphingomyelin and phosphatidylethanolamine. As in the lung surfactant, the majority of tubal PC is represented by its disaturated form dipalmitoylphosphatidylcholine (DPPC), known as a powerful surface-active agent. The concentration of PC and DPPC is higher in tubal washing than in the whole tissue, suggesting the existence of an active secretory process. Incubation of tubal mucosa with 14C-choline resulted in the biosynthesis of radiolabelled PC and DPPC at a ratio similar to the lung. These data provide further evidence for the existence of a surface-active agent in the Eustachian tube, chemically similar to the lung surfactant and probably produced through similar metabolic pathways.