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Biomedical subjects

G Back

Publications and source records attributed to G Back.

6 recordsLinked to original sources

Harmine action in rats with lymphostatic encephalopathy.

In rats with lymphostatic encephalopathy the duration of harmine tremor was lengthened, and the brain concentrations of harmine decreased more slowly than in sham-operated controls. The tremor began simultaneously in both rat groups at coinciding brain concentrations of harmine. In rats with lymphostatic encephalopathy harmine concentrations in brain at the termination of tremor lay in the same range as in sham-operated controls. The plasma concentrations of harmine were not changed by the disease. It is concluded that during lymphostatic encephalopathy the lymphatic drug elimination from brain is impaired whereas--at least for harmine--the blood-brain barrier functions as normal.

Alkaloids

Effects of caffeine and ethanol on the blood-brain barrier in rats.

In rats, pretreatment with caffeine or ethanol shortens the duration of the harmine tremor and decreases the brain concentrations of this alkaloid. Caffeine and ethanol do not influence the plasma concentration of harmine, its plasma protein binding and its cerebral concentration at the termination of the tremor. The findings are regarded as indicative of a reduction by caffeine and ethanol of the blood-brain barrier permeability to harmine.

Animals

Seasonal variations of cardiac output in rats.

Cardiac output of rats shows seasonal variations with low values in spring and summer and high ones in autumn and winter. The stroke volume was much more implicated in these changes than the heart rate. The seasonal changes of cardiac output are probably due to changes of thyroid function.

Animals

Effect of antiphologistics on blood-brain barrier in lymphostatic encephalopathic and in normal rats.

Injection of the tremorigenic alkaloid harmine into lymphostatic encephalopathic rats leads to a longer duration of tremor and higher brain concentrations than in sham-operated controls. In lymphostatic encephalopathic as well as in normal rats different antiphlogistics shorten the tremor duration and decrease harmine concentration in brain. The antiphlogistics do not influence the plasma concentration of harmine, its protein binding and its tremorend concentration in brain. The effect of antiphlogistics in lymphostatic encephalopathic rats is considered as a consequence of the reduced blood-brain barrier permeability. Obviously in sick animals the blood-brain barrier permeability for harmine is not increased; the prolonged harmine tremor and the increased alkaloid concentration in the brain are consequences of the impaired cerebral lymphatic drainage only.

Alkaloids

The effect of aprotinin on the harmine-induced tremor in lymphostatic encephalopathic and normal rats.

In normal and lymphostatic encephalopathic rats, aprotinin pretreatment alters the duration of the harmine tremor and the cerebral concentration of the alkaloid; low doses shorten the tremor and decrease the concentration, a high dose causes the opposite. Aprotinin may decrease or increase the blood-brain barrier permeability of harmine. Because the findings are similar in both groups of rats the blood-brain barrier for harmine is assumed to be intact in lymphostatic encephalopathy. However, sick rats possibly suffer from an impaired cerebral elimination of harmine.

Alkaloids