Characterization of the cyclic nucleotide phosphodiesterase subtypes involved in the regulation of the L-type Ca2+ current in rat ventricular myocytes.

ABSTRACT: The effects of several phosphodiesterase (PDE) inhibitors on the L-type Ca current (I(Ca)) and intracellular cyclic AMP concentration ([cAMP]i) were examined in isolated rat ventricular myocytes. The presence of mRNA transcripts encoding for the different cardiac PDE subtypes was confirmed by RT-PCR. IBMX (100 microM), a broad-spectrum PDE inhibitor, increased basal I(Ca) by 120% and [cAMP]i by 70%, similarly to a saturating concentration of the beta-adrenoceptor agonist isoprenaline (1 microM). However, MIMX (1 microM), a PDE1 inhibitor, EHNA (10 microM), a PDE2 inhibitor, cilostamide (0.1 microM), a PDE3 inhibitor, or Ro20-1724 (0.1 microM), a PDE4 inhibitor, had no effect on basal I(Ca) and little stimulatory effects on [cAMP]i (20-30%). Each selective PDE inhibitor was then tested in t

SUBMITTER: Verde I 

PROVIDER: S-EPMC1565993 | biostudies-literature | 1999 May

REPOSITORIES: biostudies-literature