FIG. 5.

Cardiac myocyte cAMP–PKA signaling. Cardiac myocytes were isolated from control (C) mice and from mice that had received AAV8.UCn2 (UC) gene transfer 6 weeks previously. Cyclic AMP and protein kinase A (PKA) activity were assesses in the unstimulated (basal) state and after stimulation with isoproterenol (Iso, 10 μM, 10 min) and, in separate experiments, NKH477 (NKH, 10 μM, 10 min). NKH477 is a water-soluble forskolin analog that stimulates adenylate cyclase independently of β-adrenergic receptors. Numbers in columns denote group size. Left: cAMP production. No group differences were seen in basal or NKH477-stimulated cAMP production. However, β-adrenergic receptor-dependent cAMP production was increased after UCn2 gene transfer (Iso; p=0.04). Columns and error bars denote means and SE; numbers in columns denote group size; numbers above the columns indicate p values determined by Student t test (unpaired, two-tailed). Middle: PKA activity. PKA activity was assessed in cardiac myocytes pooled from each group; the means of five replicates are shown. PKA activity appeared to show small increases (22–34%) in PKA activity after UCn2 gene transfer. Right: PKA expression. No group differences in the expression or phosphorylation of the PKA catalytic subunit (PKA-C) were seen.