Protein kinase C isoforms and A 1 adenosine receptors in porcine coronary smooth muscle cells

Abstract

We have previously reported that prolonged exposure of porcine coronary arteries to adenosine agonists upregulates protein kinase C (PKC) through the activation of adenosine A 1 receptor-coupled to pertussis toxin sensitive G-protein(s) [Am. J. Physiol. 264 (1993) H1465; Am. J. Physiol. 269 (1995) H1619]. The mechanism(s) by which A 1 adenosine receptor upregulates PKC (isoforms) are not yet clearly understood. In the present study, we identified the α, β 1, β 2, γ, ε, and ζ PKC isoforms that were upregulated by adenosine A 1 receptor agonist as a possible mechanism(s) involved for this upregulation. Incubation of porcine coronary smooth muscle cells (PCSMC) with adenosine A 1 receptor agonist (2s)- N 6-[2-endo-norbornyl]adenosine (ENBA) caused an upregulation of PKC (isoforms), which were blocked by adenosine A 1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). Western blot analysis using specific antibodies to PKC isoforms indicated that all the isoforms tested (α, β I, β II, μ, γ, δ, ε, and ζ) were present in the primary cultured smooth muscle cells from porcine coronary artery. Western blot studies indicated that PKC α, β I, β II, γ, ε, and ζ isoforms were upregulated in a dose dependent manner by adenosine agonist (ENBA) and PKC δ and μ were not altered.