Spermine and philanthotoxin potentiate excitatory amino acid responses of Xenopus oocytes injected with rat and chick brain RNA.
The effects of spermine and a synthetic analogue (PhTX-343) of the polyamine amide toxin, delta-philanthotoxin, on the responses of Xenopus oocytes to application of amino acids were examined using voltage clamp. The oocytes were injected with either total rat brain RNA or chick cerebrum, poly(A+)RNA. The responses to N-methyl-D-aspartate and L-kainate were potentiated by low concentrations (10(-11)-10(-7) M) of PhTX-343 and by 10(-5)-10(-4) M spermine. There was variability between oocytes in terms of their responsiveness to these compounds and recovery from their effects was slow and often incomplete. Prolonged or repeated applications of PhTX-343 and spermine eventually resulted in inhibition. Higher concentrations of these compounds always inhibited the responses to acidic amino acids. Low concentrations of PhTX-343 and spermine also potentiated the responses to nicotine and gamma-aminobutyric acid. These results are discussed in terms of the postulated polyamine binding site on the N-methyl-D-aspartate receptor.
Brackley
P
P
Department of Zoology, University of Nottingham, U.K.
Goodnow
R
R
Nakanishi
K
K
Sudan
H L
HL
Usherwood
P N
PN
D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001514:Bee Venoms / Q000494:pharmacology*; D001921:Brain / Q000502:physiology*; D002645:Chickens; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008845:Microinjections; D016202:N-Methylaspartate; D009498:Neurotoxins / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010069:Oxadiazoles / Q000494:pharmacology; D011061:Poly A / Q000008:administration & dosage / Q000235:genetics; D011073:Polyamines; D016318:Quisqualic Acid; D012313:RNA / Q000008:administration & dosage / Q000235:genetics*; D012333:RNA, Messenger; D051381:Rats; D011919:Rats, Inbred Strains; D013096:Spermine / Q000502:physiology*; D014862:Wasp Venoms / Q000494:pharmacology*; D014981:Xenopus
D000596:Amino Acids; D001514:Bee Venoms; D009498:Neurotoxins; D010069:Oxadiazoles; D011073:Polyamines; D012333:RNA, Messenger; D014862:Wasp Venoms; D011061:Poly A; D013096:Spermine; D001224:Aspartic Acid; D012313:RNA; D016202:N-Methylaspartate; C034092:delta-philanthotoxin; D016318:Quisqualic Acid; D007608:Kainic Acid