Developmental changes of potassium currents of embryonic leech ganglion cells in primary culture

Meis, Susanne; Deitmer, Joachim W.

doi:10.1002/(sici)1097-4547(19971215)50:6<967::aid-jnr7>3.0.co;2-b

Cited by 4 publications

(1 citation statement)

References 55 publications

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“…Enzymatic treatment followed by mechanical dissociation of the subesophageal ganglion complex was performed according to a previously described procedure (Ivic et al, 1995). Previous research has shown that an approach using only mechanical trituration of isolated leech ganglia provides for the presence of only neurons in primary culture (Meis and Deitmer, 1997). Thus, we decided to follow the procedure involving enzymatic treatment of the snail ganglion using the proteolytic enzyme pronase to separate neurons from glial cells (Balaban et al, 1990).…”

Section: Methodsmentioning

confidence: 99%

Modification of Glial Response in Hibernation

et al. 2014

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Hibernation is a dormant state of some animal species that enables them to survive harsh environmental conditions during the winter seasons. In the hibernating state, preservation of neuronal rhythmic activity at a low level is necessary for maintenance of suspended forms of behavior. As glial cells support rhythmic activity of neurons, preservation of brain function in the hibernating state implies accompanying modification of glial activity. A supportive role of glia in regulating neuronal activity is reflected through the activity of inwardly rectifying K+ channels (Kir). Therefore, we examined electrophysiological response, particularly Kir current response, of glial cells in mixture with neurons acutely isolated from active and hibernating land snail Helix pomatia. Our data show that hibernated glia have significantly lower inward current density, specific membrane conductance, and conductance density compared with active glia. The observed reduction could be attributed to the Kir currents, since the Ba2+-sensitive Kir current density was significantly lower in hibernated glia. Accordingly, a significant positive shift of the current reversal potential indicated a more depolarized state of hibernated glia. Data obtained show that modification of glial current response could be regulated by serotonin (5-HT) through an increase of cGMP as a secondary messenger, since extracellular addition of 5-HT or intracellular administration of cGMP to active glia induced a significant reduction of inward current density and thus mimicked the reduced response of hibernated glia. Lower Kir current density of hibernated glia accompanied the lower electrical activity of hibernated neurons, as revealed by a decrease in neuronal fast inward Na+ current density. Our findings reveal that glial response is reduced in the hibernating state and suggest seasonal modulation of glial activity. Maintenance of low glial activity in hibernation could be important for preservation of brain rhythmic activity and survival of the animal.

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Section: Methodsmentioning

confidence: 99%

Modification of Glial Response in Hibernation

et al. 2014

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Development of ionic currents of zebrafish slow and fast skeletal muscle fibers

et al. 2006

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Voltage-gated Na+ and K+ channels play key roles in the excitability of skeletal muscle fibers. In this study we investigated the steady-state and kinetic properties of voltage-gated Na+ and K+ currents of slow and fast skeletal muscle fibers in zebrafish ranging in age from 1 day postfertilization (dpf) to 4-6 dpf. The inner white (fast) fibers possess an A-type inactivating K+ current that increases in peak current density and accelerates its rise and decay times during development. As the muscle matured, the V50s of activation and inactivation of the A-type current became more depolarized, and then hyperpolarized again in older animals. The activation kinetics of the delayed outward K+ current in red (slow) fibers accelerated within the first week of development. The tail currents of the outward K+ currents were too small to allow an accurate determination of the V50s of activation. Red fibers did not show any evidence of inward Na+ currents; however, white fibers expressed Na+ currents that increased their peak current density, accelerated their inactivation kinetics, and hyperpolarized their V50 of inactivation during development. The action potentials of white fibers exhibited significant changes in the threshold voltage and the half width. These findings indicate that there are significant differences in the ionic current profiles between the red and white fibers and that a number of changes occur in the steady-state and kinetic properties of Na+ and K+ currents of developing zebrafish skeletal muscle fibers, with the most dramatic changes occurring around the end of the first day following egg fertilization.

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