Search PubMed⌕ Search

Biomedical subjects

G Franck

Publications and source records attributed to G Franck.

At least 127 records · Page 7Linked to original sources
PubMed1979

Effect of K+ ions on kinetic properties of the (Na+, K+)-ATPase (EC 3.6.1.3) of bulk isolated glial cells, perikarya and synaptosomes from rabbit brain cortex.

Progress curves of the enzymatic reactions show that ATPases of bulk isolated glial cells, perikarya and synaptosomes exhibit hysteretic change. Initial velocities of enzyme activities were therefore obtained according to the equation valid for the hysteretic model. The (Na+, K+)-ATPase activities of the same brain fractions were measured before or after NaI treatment. Only glial and synaptosomal enzyme could be adequately extracted by using this procedure. Attempts to purify the (Na+, K+)-ATPase from brain perikarya by NaI extraction were unsuccessful. In order to determine the effect of the K+ ions on enzymic physiological efficiency (phys. eff.; i.e., the ratio Vmax/Kmapp) the variation of (Na+, K+)-ATPase activities from each brain fraction was measured as a function of Mg.ATP2- concentration in the presence of 5 and 20 mM K+ ions. High K+ ion concentrations (20 mM) increased the physiological efficiency of glial enzyme and decreased the same kinetic parameter in neuronal (perikaryal as well as synaptosomal) enzyme preparations. Results are discussed in relation to a possible distribution of distinct enzyme in different brain cell populations as well as a possible role of glial cells in an active regulation of K+ ion extracellular fluid in the CNS.

Adenosine Triphosphatases↗
PubMed1979

The autoregulation of cerebral blood flow, the cerebrovascular reactivity and their interaction in the Shy-Drager syndrome.

The experimental study of the autoregulation of cerebral blood flow (CBF), of the cerebrovascular reactivity and of their interaction is performed in a confirmed case of Shy-Drager syndrome, by means of the xenon-clearance technique. The basal mean regional CBF is slightly depressed. The cerebrovascular reactivities to variation in paCO2 and to local cerebral activation are maintained. The inferior threshold of breaking of autoregulation is raised. A competition between the effects on CBF of autoregulation loss and of metabolic regulation is demonstrated. The latency of operation of the autoregulation is evoked by the analysis of the CBF measurements and is confirmed by the simultaneous EEG study.

Aged↗