K+ differentially affects the excitatory amino acids- and carbachol-elicited inositol phosphate formation in rat brain synaptoneurosomes

A Specific Trarisduction Mechanism for the Glutamate Action on Phosphoinositide Metabolism via the Quisqualate Metabotropic Receptor in Rat Brain Synaptoneurosomes: I. External Na+ Requirement

“…Our results indicate that known depolarizing agents (K', veratridine, and monensin), as well as others (some amiloride derivatives), whatever their mode of action on the membrane potential, stimulate the metabolism of IPS (Fig. 2 and Tables 1 and 2) (Guiramand et al, 1989). These observations are in agreement with those of other authors showing that in addition to K+, veratridine, and monensin, ouabain, scorpion toxins, pumiliotoxin B, batrachotoxin, and aconitine also increase accumulation of IPS in various experimental models (Kendall and Nahorski, 1984;Habermann and Laux, 1986;Gusovsky et al, 1986;Audigier et al, 1988;Gusovsky and Daly, 1988ab;Baird andNahorski, 1989, 1990; Benuck et al, 1989ab).…”

“…These data strongly suggest that Glu and K+ share at least a common step in their mechanism of activation of phosphoinositide breakdown, whereas Glu and Carb seem to use independent ways to stimulate production of Ips (Guiramand et al, 1989). The most likely common intermediate step of the mechanisms of Glu-and K+-induced formation of IPS is depolarization and/or Na+ flux.…”

“…One can thus suppose that QA and muscarinic receptors are not coupled to phosphoinositide breakdown by the same GTP-binding protein (Nicoletti et al, 1988;Ambrosini and Meldolesi, 1989). In the same line, we demonstrated that K+ differentially affects the formation of IPS induced by Glu and carbachol (Carb), a muscarinic agonist, in rat forebrain synaptoneurosomes (Guiramand et al, 1989). Increasing the concentration of K+ induced production of IPS that is not cumulative with that evoked by Glu but is more than additive with that elicited by Carb.…”

Excitatory amino acid-, except 1S,3R-ACPD, induced transient high stimulation of phosphoinositide metabolism during hippocampal neuron development

“…The fact that Glu weakly activated NMDA receptors in hippocampal culture probably stems from a desensitization of this receptor by Glu at high concentration. 25,29 In this case, therefore, Glu action preferentially reflects an ionotropic action on AMPA/KA receptors, and a minor action via NMDA receptors. The remaining response originates from Glu metabotropic receptor activation.…”

Involvement of Calcium Influx in Muscarinic Cholinergic Regulation of Phospholipase C in Cerebellar Granule Cells

“…However, exper-E. del Rio, D . G. Nicholls, and C. P. Downes 535 iments using brain slices or synaptoneurosome preparations have shown that depolarisation induced by KC1 has a marked Ca t+ -mediated effect on neurotransmitter-stimulated inositol phosphate responses (Baird and Nahorski, 1989 ;Guiramand et al ., 1989 ;Fisher et al ., 1992) . Moreover, in permeabilized SK-N-SH neuroblastoma cells, Ca 2+ in the range 10-100 nM markedly potentiates agonist-and GTPyS-activated inositol phosphate accumulation (Fisher et al ., 1989) .…”