Cellular distribution and pharmacological sensitivity of low K(m) cyclic nucleotide phosphodiesterase isozymes in human cardiac muscle from normal and cardiomyopathic subjects

P. J. Silver, P. Allen, J. H. Etzler, L. T. Hamel, R. G. Bentley, E. D. Pagani

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Cyclic nucleotide phosphodiesterase (PDE) isozymes isolated by DEAE-Sephacel or Mono-Q High Performance Liquid Chromatography from cardiac left ventricular tissue of normal subjects and patients with end-stage heart failure have been compared. With both seperation techniques, four major peaks of PDE activity were evident in the soluble fractions; only one peak of activity was present in particulate fractions. The specific activity of the particulate PDE from myopathics was approximately 30-50% of that of normals while the specific activity of a soluble form of this PDE (peak IIIa) was reduced by 30% in myopathics. No differences in comparison of the other peaks of PDE activity were evident. The particulate PDE isozyme has a low K(m) for cAMP (0.27-0.29 μM), is inhibited by cGMP (60-80% at 1 μM), is sensitive to inhibition by submicromolar concentrations of CI-930 but not rolipram, and is competitively inhibited by milrinone (K(i) = 0.3 μM). The first soluble peak of the PDE activity hydrolyzes both cAMP and cGMP and is stimulated by calmodulin while cyclic AMP hydrolysis by peak II PDE is stimulated by cGMP. The other soluble peak III fractions (IIIa and IIIb) hydrolyze cAMP; peak IIIa is inhibited by cGMP or by CI-930 and milrinone, whereas peak IIIb is also inhibited by rolipram when the cardiotonic sensitive PDE is inhibited by CI.930. Thus, cardiotonic-sensitive, cGMP-inhibitable, low K(m) cAMP PDE is present in both the soluble and particulate fractions of human cardiac left ventricular muscle of hearts from normal and cardiomyopathic subjects while the rolipram-sensitive PDE is present in the soluble fraction. The major differences in PDE activity of myopathic relative to normal left ventricular tissue are a reduced specific activity and V(max) of particulate PDE and one of the soluble peak III PDEs.

Original languageEnglish (US)
Pages (from-to)13-25
Number of pages13
JournalSecond Messengers and Phosphoproteins
Volume13
Issue number1
StatePublished - 1990
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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