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Titolo:
PHARMACOLOGICAL CHARACTERIZATION OF THE VOLTAGE-DEPENDENT CA2-NERVOUS-SYSTEM( CHANNELS PRESENT IN SYNAPTOSOMES FROM RAT AND CHICKEN CENTRAL)
Autore:
MAUBECIN VA; SANCHEZ VN; SIRI MDR; CHERKSEY BD; SUGIMORI M; LLINAS R; UCHITEL OD;
Indirizzi:
UNIV BUENOS AIRES,FAC MED,SCH MED,INST BIOL CELULAR,PARAGUAY 2155,2 PISO RA-1121 BUENOS AIRES DF ARGENTINA UNIV BUENOS AIRES,FAC MED,SCH MED,INST BIOL CELULAR RA-1121 BUENOS AIRES DF ARGENTINA NYU,MED CTR,DEPT PHYSIOL & NEUROSCI NEW YORK NY 10016
Titolo Testata:
Journal of neurochemistry
fascicolo: 6, volume: 64, anno: 1995,
pagine: 2544 - 2551
SICI:
0022-3042(1995)64:6<2544:PCOTVC>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
OMEGA-CONOTOXIN GVIA; CALCIUM CHANNELS; P-TYPE; FUNCTIONAL EXPRESSION; BRAIN; NEURONS; RELEASE; TOXIN; DEPOLARIZATION; DIVERSITY;
Keywords:
CA2+ UPTAKE; CHICKEN BRAIN SYNAPTOSOMES; RAT SYNAPTOSOMES; TOXINS; VOLTAGE-DEPENDENT CA2+ CHANNELS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
42
Recensione:
Indirizzi per estratti:
Citazione:
V.A. Maubecin et al., "PHARMACOLOGICAL CHARACTERIZATION OF THE VOLTAGE-DEPENDENT CA2-NERVOUS-SYSTEM( CHANNELS PRESENT IN SYNAPTOSOMES FROM RAT AND CHICKEN CENTRAL)", Journal of neurochemistry, 64(6), 1995, pp. 2544-2551

Abstract

The voltage-dependent calcium channels present in mammalian and chicken brain synaptosomes were characterized pharmacologically using specific blockers of L-type channels (1,4-dihydropyridines), N-type channels (omega-conotoxin GVIA), and P-type channels [funnel web toxin (FTX) and omega-agatoxin IVA], K+-induced Ca2+ uptake by chicken synaptosomes was blocked by omega-conotoxin GVIA (IC50 = 250 nM). This toxin at 5mu M did not block Ca2+ entry into rat frontal cortex synaptosomes. FTX and omega-agatoxin IVA blocked Ca2+ uptake by rat synaptosomes (IC50 = 0.17 mu l/ml and 40 nM, respectively). Likewise, in chicken synaptosomes, FTX and omega-agatoxin IVA affected Ca2+ uptake. FTX (3 mu l/ml) exerted a maximal inhibition of 40% with an IC50 similar to the oneobtained in rat preparations, whereas with omega-agatoxin IVA saturation was not reached even at 5 mu M. In chicken preparations, the combined effect of saturating concentrations of FTX(1 mu l/ml) and different concentrations of omega-conotoxin GVIA showed no additive effects. However, the effect of saturating concentrations of FTX and omega-conotoxin GVIA was never greater than the one observed with omega-conotoxinGVIA. We also found that 60% of the Ca2+ uptake by rat and chicken synaptosomes was inhibited by omega-conotoxin MVIID (1 mu M), a toxin that has a high index of discrimination against N-type channels. Conversely, nitrendipine (10 mu M) had no significant effect on Ca2+ uptake in either the rat or the chicken. In conclusion, Ca2+ uptake by rat synaptosomes is potently inhibited by different P-type Ca2+ channel blockers, thus indicating that P-type channels are predominant in this preparation. In contrast, Ca2+ uptake by chicken synaptosomes is sensitiveto omega-conotoxin GVIA, FTX, omega-agatoxin IVA, and omega-conotoxinMVIID. This suggests that a channel subtype with a mixed pharmacologyis present in chicken synaptosomes.

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Documento generato il 25/11/20 alle ore 18:38:07