Neurobiology 7. (1999)

2. szám - Research reports

Sixth Annual Meeting of HNS 329 tentacles and this way can affect the heart functions as neurohormone. CCAP as neurohormone may have also a remote control on the circulatory system and the whole body musculature. This work was supported by DAAD and a grant from OTKA. Grant No. 16015. DYSTROPHIN IMMUNOREACTIVITY IN PKRIVASCULAR ASTROCYTES OF THE DEVELOPING RAT BRAIN Jancsik, V. and Hajós, F. Department of Anatomy and Histology, University of Veterinary Science, Budapest, Hungary The faulty expression of the 427 Kd member of the dystrophin family proteins is responsible for muscular dystrophy through an action on the neuromuscular junction. Dystrophin has been demonstrated to be present also in CNS synapses and in astroglia cells. The present work was focused on the particularly intense dystrophin immunoreactivity observed in the pericapillary astrocyte processes. Using a monoclonal antibody we investigated the postnatal appearance of dystrophin-immunoreactivity in the cytoplasm of astrocytes and around the capillaries of the hippocampus and cerebral cortex. In the adult, the scarce ribosomal apparatus of astrocytes gives a faint immunostaining, whereas the pericapillary processes are densely packed with immunoprecipitate. Until postnatal day 10, no pericapillary stainig was observed. At this age, staining occurred on the pericapillary astrocyte membrane facing the basal lamina of the capillary endothelium. On postnatal day 20, staining became more widespread and by day 30 it was similar to that in the adult. The topography and time course of appearance of the pericapillary dystrophin immunoreactivity suggests an association of dystrophin family proteins with the formation of the blood-brain-barrier. MEMBRANE CURRENTS OF SENSORY NEURONS - A COMPUTER MODEL STUDY JANDÓ, G. and CZÉH, G. Institute of Physiology and Neuropharmacology Research Group, Institute of Pharmacology, Univ. Med. School of Pécs, Hungary Theoretical background and interpretation of ramp-command voltage induced membrane currents is less firm than that of the voltage clamp data obtained with classical step-commands. Step commands clamp the membrane potential at a desired level for a period of time and allow to study the time and voltage dependence of the step-elicited membrane currents. Data obtained with this technique can be interpreted in the framework of Hodgkin-Huxley theory. Disadvantages of the technique include contribution of capacitive currents involved in the rapid voltage changes at the onset of steps, and the long time required to collect sets of data needed for detailed 1-V functions. Ramp commands eliminate problems of capacitive transients and quickly produce very detailed data on voltage dependence of membrane currents but leave time-dependent properties of the membranes obscure. We have developed a computer model which can describe the individual properties of the recordings obtained from patch-clamped sensory neurons. Proper setting of quantitative values of the model makes it able to generate curves similar to that obtained from voltage clamped sensory neurons. The model parameters were found with a gradient descent algorithm based on the least

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