Cell-type specific depression of neuronal excitability in rat hippocampus by activation of ATP-sensitive potassium channels.

The contribution of ATP-sensitive potassium (K(ATP)) channels to neuronal excitability was studied in different types of pyramidal cells and interneurones in hippocampal slices prepared from 9- to 15-day-old rats. The presence of functional K(ATP) channels in the neurones was detected through the sensitivity of whole-cell currents to diazoxide, a K(ATP) channel opener, and to tolbutamide, a K(ATP) channel inhibitor. The percentages of neurones with K(ATP) channels increase in the sequence: CA1 pyramidal cells (37%)< View Article and Find Full Text PDF

Differential activation of ATP-sensitive potassium channels during energy depletion in CA1 pyramidal cells and interneurones of rat hippocampus.

In the hippocampus, pyramidal cells are more vulnerable than granule cells and interneurones to energy depletion during hypoxia and ischaemia. The aim of the present study was to explore whether this difference is related to the lower expression of adenosine 5'-triphosphate-sensitive potassium (K(ATP)) channels in pyramidal cells compared to other hippocampal neurones. Hippocampal slices were prepared from 10- to 13-day-old rats, and CAI pyramidal cells and interneurones of the stratum radiatum were visually and electrophysiologically identified.

Cell-type specific expression of ATP-sensitive potassium channels in the rat hippocampus.

1. The distribution of ATP-sensitive K+ channels (KATP channels) was investigated in four cell types in hippocampal slices prepared from 10- to 13-day-old rats: CA1 pyramidal cells, interneurones of stratum radiatum in CA1, complex glial cells of the same area and granule cells of the dentate gyrus. The neuronal cell types were identified visually and characterized by the shapes and patterns of their action potentials and by neurobiotin labelling.

Endogenous trypsin receptors in Xenopus oocytes: linkage to internal calcium stores.

The effects of the protease trypsin, externally applied to full-grown oocytes of Xenopus laevis, were studied using electrophysiology and fluorometry. The following results were obtained: trypsin in concentrations of 0.1 microgram/ml to 1 mg/ml liberated Ca2+ from internal stores and evoked large transient currents of up to 5 microA in bath solutions containing 1 mM or no Ca2+.

Inhibition of ATP-sensitive K+ channels of mouse skeletal muscle by disopyramide.

Single ATP-sensitive K+ channels (KATP channels) were studied in inside-out membrane patches excised from mouse skeletal muscle. The class Ia antiarrhythmic, disopyramide (5-100 microM), applied to the cytoplasmic membrane surface inhibited KATP channels at -40 and +40 mV. Channel inhibition by disopyramide started slowly and reached an almost stationary level within 1 min.