K+ differentially affects the excitatory amino acids- and carbachol-elicited inositol phosphate formation in rat brain synaptoneurosomes.
K+, excitatory amino acids (EAAs) and carbachol (Carb) were tested separately or in pairs for their ability to stimulate inositol phosphate (IPs) formation in rat forebrain synaptoneurosomes. K+ ions per se, stimulate IPs synthesis (158% of the control value) as well as EAAs and Carb. The glutamate (Glu)- and quisqualate (QA)-elicited IPs formation is not additive with that evoked by K+. Inversely, K+ ions (up to 30 mM) potentiate the Carb-induced IPs accumulation. These results indicate that QA (or Glu) and Carb enhance IPs formation independently and that QA- and K+ -induced IPs responses are interdependent. This suggests that they share a 'common intermediate' step in the multistep mechanism which leads from receptor activation to the IPs synthesis. This 'common intermediate' step may be depolarization and/or Na+ influx.
Guiramand
J
J
Centre CNRS-INSERM de Pharmacologie-Endrocrinologie, Montpellier, France.
Nourigat
A
A
Sassetti
I
I
Recasens
M
M
D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001923:Brain Chemistry / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology*; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism*; D005971:Glutamates / Q000494:pharmacology; D018698:Glutamic Acid; D007295:Inositol Phosphates / Q000378:metabolism*; D016202:N-Methylaspartate; D010069:Oxadiazoles / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D016318:Quisqualic Acid; D051381:Rats; D013403:Sugar Phosphates / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*
D000596:Amino Acids; D005971:Glutamates; D007295:Inositol Phosphates; D010069:Oxadiazoles; D013403:Sugar Phosphates; D001224:Aspartic Acid; D018698:Glutamic Acid; D016202:N-Methylaspartate; D016318:Quisqualic Acid; D002217:Carbachol; D011188:Potassium