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M Madeja

Publications and source records attributed to M Madeja.

41 records · Page 3Linked to original sources
PubMed1992

Time course of glutamate receptor expression in individual oocytes of Xenopus laevis after injection of rat brain RNA.

1. The receptor for the neurotransmitter glutamate was functionally expressed in oocytes of Xenopus laevis after microinjection of rat brain RNA. The functional differentiation of this receptor type was further analyzed. 2. The development of the sensitivity to the agonists showed a time course which was differential for the various ligands in individual oocytes. 3. Sensitivity appeared after one day for kainate (KA), after two days for alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) and quisqualate (QA), and after five days for N-methyl-D-aspartate (NMDA). 4. The KA response was markedly reduced by simultaneous application of AMPA. This was even found on the first day when an agonistic AMPA reaction was not detectable. 5. NMDA and non-NMDA receptors can clearly be differentiated by their delay of expression.

Animals↗
PubMed1991

Membrane currents elicited by the epileptogenic drug pentylenetetrazole in the native oocyte of Xenopus laevis.

The effects of the epileptogenic agent pentylenetetrazole (PTZ) on membrane currents of native oocytes of Xenopus laevis were studied. PTZ elicits a response that consists of two inward currents. The first one is interpreted to be due to a decrease of potassium permeability since: (1) the input resistance is increased; (2) the equilibrium potential is near that of potassium; (3) the current is decreased during administration of potassium channel blocking agents; and (4) the PTZ response can be mimicked by blocking potassium channels without PTZ application. The second one is interpreted to be due to an increase of chloride permeability since: (1) the input resistance is decreased; (2) the equilibrium potential is near that of chloride; and (3) the response is decreased during administration of chloride blocking agents. These findings correspond to some extent with those made in neurons.

Animals↗
PubMed1991

Inward currents elicited by stream of fluid during transmitter-induced current oscillations in RNA-injected oocytes of Xenopus laevis.

A stream of fluid elicited an inward current in RNA-injected oocytes of Xenopus laevis during transmitter-induced current oscillations (stream evoked inward current, Ii,st). The Ii,st showed the following characteristics: (1) amplitude and duration (half width time) ranged between 10 and 300 nA and 1 and 3 s, respectively. (2) The Ii,st could be evoked only during transmitter-induced current oscillations; with blockade of the oscillations the Ii,st disappeared. (3) The induction of the Ii,st was independent of the composition of the washing fluid.

Animals↗