Effect of MANT-nucleotides on L-type calcium currents in murine cardiomyocytes.
Naunyn Schmiedebergs Arch Pharmacol
; 383(6): 573-83, 2011 Jun.
Article
em En
| MEDLINE
| ID: mdl-21484439
ABSTRACT
Membranous adenylyl cyclases play a major role in G-protein-coupled receptor signalling and regulate various cellular responses, such as cardiac contraction. Cardiac apoptosis and development of cardiac dysfunction is prevented in mice lacking AC 5, a predominant isoform in the heart. In the search for a potent and selective AC 5 inhibitor, we recently identified 2'(3')-methylanthraniloyl-inosine-5'-triphosphate(MANT-ITP) as the most potent AC 5 inhibitor with a K ( i ) of 13 nM. Therefore, AC inhibition of MANT-ITP was assessed in ventricular cardiomyocytes and compared to three other MANT-nucleotides to evaluate its effect on cardiac signalling. Basal and isoproterenol-induced L-type calcium currents (I (Ca,L)) in murine ventricular cardiomyocytes were recorded by whole-cell patch-clamp technique, using four different MANT-nucleotides. The effects of the MANT-nucleotides on I (Ca,L) were unexpectedly complex. All MANT-nucleotides exhibited an inhibitory effect on basal I (Ca,L). Additionally, several MANT-nucleotides, i.e., MANT-ITPγS, MANT-ATP, and MANT-ITP, caused a strong initial increase in basal I (Ca,L) within the first 2.5 min that appeared to be unrelated to AC 5 inhibition. However, we detected a significant reduction on isoproterenol-induced I (Ca,L) with MANT-ITP, supporting the notion that AC 5 plays an important role in agonist-stimulated activation of I (Ca,L). Collectively, MANT-nucleotides are useful tools for the characterization of recombinant ACs, for fluorescence studies and crystallography, but in intact cardiomyocytes, caution must be exerted since MANT-nucleotides apparently possess additional effects than AC 5 inhibition, limiting their usefulness as tools for intact cell studies.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Canais de Cálcio Tipo L
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Miócitos Cardíacos
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Inibidores de Adenilil Ciclases
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Nucleotídeos de Inosina
Limite:
Animals
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article