No abstract

No abstract

We studied the effect of "chemical" (induced by the action of sodium thiosulfate, STS) hypoxia on the potassium conductance of the membrane of pheochromocytoma cells. Application of 1 to 10 mM STS decreased in a dose-dependent manner the amplitude of integral potassium current without changes in the voltage dependence of its activation. The concentration dependence of the action of STS on the amplitude of potassium current was estimated using the Boltzmann equation. The value of concentration for 50% inhibition was 2.7 ± 0.2 mM, while the slope coefficient was 0.9 ± 0.2 mM −1 . In the presence of 10 mM STS, the decrease in the amplitude of potassium current reached, on average, 55%. Therefore, "chemical" hypoxia influences rather significantly the potassium conductance of the membrane of pheochromocytoma РС12 cells.

PAGE THE PROBLEM To evaluate the efficacy of reduction in media serum availability as a technique for indueinq neural differentiation and formation of neuron-I ike axonal and Junctional processes in cultured neuroblastoma ceils. THE FINDINGS Culture morphological characteristics were monitored for 96 hours after sub-cultivation in support media containing varying concentrations of available serum. Cultivation in media with reduced serum concentrations increased overall proportion of differentiated cells, increased the yield of extended neurite processes, increased the length of the neurites, increased the number of varicosities on the neurites, and increased the number of sites where varicosities on neurites from different cells overlapped or abutted. The results suggest that media serum starvation is an effective technique for inducing growth characteristics in neuroblastoma cell cultures sufficient for neurophysiological study of induced synapogenesis in the culture. APPLICATION The results indicate that we can readily grow neuroblastoma cultures which exhibit characteristics usually found only in natural nervous tissue. The induced characteristics include multiple interactions at sites on the neurites occupied by varicosities, as well as overall Increases in neuritogenesis. These induced characteristics will enable us to attempt to demonstrate induction of functional synaptic junctions between the cells at the sites of varicosity Interaction, ADMINISTRATIVE INFORMATION This investigation was conducted under NMRDC Work Unit No. 61153N. MR04101.001-5014, "(U) Cell culture modeling of neurophysiological pathology and brain associative processes." It ABSTRACT Previous studies have demonstrated that cultured cloned ceils extend neurites after exposure to media supplemented with reduced concentration of serum. The present experiment on cloned neuroblastoma cells (Neuro-2a) corroborates and extends the past studies. N2A cells were cultivated in media containing 10% fetal bovine serum (FBS). After 24 hrs the cells were subcultivated into media containing either 10%, 5%, or 1% FBS; or media containing 10%, 5%, or 1% NU-SERUM V (NSV). The cells were morphologically characterized after 24, 48, 72 and 96 hours incubation. Reduced media serum concentrations increased the proportion of neurally differentiated cells, increased the overall neurite yield, increased the length of the neurites, increased the number of varicoslties on the neurites, and increased the number of potentially interactive sites where varicosities on neurites from different cells overlapped or abutted. For all measures, NSV supplementation was found to reliably induce more neuritogenesis than for equal concentrations of FBS, The present experiment suggested that morphological features suitable for long term neurophysiolo^ical investigation could be induced by incubation in media containing either 1% NSV or 1% FBS.