Comparison of basal and cAMP-stimulated protein kinase A activity in VSMC extracts prepared from cells expressing either eGFP or PKIα-eGFP
| PKA activity1-a | ||||
|---|---|---|---|---|
| eGFP | PKIα-eGFP | |||
| (−)-Antet | (+)-Antet | (−)-Antet | (+)-Antet | |
| pmol/min/mg of protein | ||||
| Basal | 197 ± 231-d | 315 ± 281-d | 65 ± 281-d | 187 ± 631-d |
| + 50 μmcAMP | 1875 ± 3101-b | 1643 ± 2611-b | 178 ± 82c,e | 1113 ± 5551-b |
The cells were grown in the absence (−) or presence (+) of 100 nm Antet for 24 hr and not otherwise stimulated with agonists before preparing extracts and measuring PKA activity. Basal activity thus results from endogenous cAMP levels in the extracts, whereas experiments not shown indicate that in vitro PKA activity is stimulated maximally by 50 μm cAMP in this preparation. The data were inspected statistically using one-way analysis of variance and Tukey’s multiple comparison test using the GraphPAD suite of software. Each value represents the mean ± standard error of three independent experiments, each performed in triplicate.
↵1-a Defined as total kemptide kinase activity observed in the extracts less the activity found when 1 μm PKI(6–22) is added to the assay buffer.
↵1-b Significantly (p < 0.05) different from basal activity in the respective extract.
1-c Significantly different (p < 0.05) from 50 μM cAMP-stimulated PKA activity in all other extracts.
↵1-d Not significantly different (p > 0.05) from basal PKA activity in all other extracts.
1-e Not significantly different (p > 0.05) from basal activity in the respective extract.