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Biomedical subjects

E Gäbler

Publications and source records attributed to E Gäbler.

7 recordsLinked to original sources

Modulation of locomotor activity by substance P in rats.

The effects of intraperitoneally or intracerebrally (DA A-10 area) administered substance P (SP) on locomotor activity of rats were studied in an exact 12-h light/12-h dark cycle changing from dark to light at 6 a.m. SP was administered either at 11 a.m. (light phase, minimal locomotor activity) or at 7 p.m. (dark phase, maximal locomotor activity). The effects of 12.5 micrograms/kg SP intracerebral and 125 micrograms/kg SP intraperitoneal were very similar. In the light phase SP produces excitation but inhibition of locomotion in darkness. Hence, the effect of SP depends on the internal mechanisms controlling motor activity and tends to level off the spontaneous circadian oscillation. We found a long lasting SP effect during both the light and dark period. The present experiments led us to the conclusion that SP has a levelling effect on locomotor activity. Probably this effect might be explained as SP's action on the dopaminergic pathway or dopamine metabolism, because the dopamine content in neurons also has a circadian rhythm.

Animals

[Effect of morphine on polyphosphoinositides of erythrocytes of spontaneously hypertensive rats].

Morphine (1 X 10(-5) mol/l) did not affect the incorporation of 32P into the phosphoinositides of erythrocytes from spontaneously hypertensive and normotensive Wistar Kyoto rats, whereas the content of triphosphoinositides was decreased. In spontaneously hypertensive rats the content of total phospholipids was decreased in the same ratio. Thus, the effect of morphine (at this concentration) on the membrane phospholipids of spontaneously hypertensive rats seems to be unspecific.

Animals

Cooperativity concepts in protein binding models--problems of cooperativity definition, detection, identification and measuring.

Cooperativity in protein-ligand binding cannot yet be treated as a urinary phenomenon (neither in investigating nor in modelling), although imaginable to rest upon some few general principles only. Knowledge of atomic details of protein-ligand interactions is still limited. Instead of a physico-chemical explanation and definition of cooperativity, a series of schematic concept has been established throughout the literature. Some dominating or merely observable features are isolated and intermixed with plausibly invented mechanistic details. These cooperativity concepts are put together and partly generalized here. From comparing these concepts with the state of binding theory on the one hand and with the nature of measured binding data on the other, some problems of understanding cooperative effects and of detecting, measuring and identifying them are pointed out. For special cases, suitable criteria and measures are recommended and graphic and mathematical techniques discussed. The limited significance and generality of current cooperativity terms is emphasized. Some different levels of understanding have to be distinguished.

Ligands