Table 2 cAMP levels and protein kinase A (PKA) activity in liver tissue are not affected by the bile acids taurolithocholic acid (TLCA) and tauroursodeoxycholic acid (TUDCA)
Bile acidInhibitorcAMP (pmol/g liver)pCREB (AE)
DMSO30.6 (3.5)0.52 (0.07)
DMSOST+H8930.1 (10.6)0.25 (0.04)**
TUDCA24.9 (7.7)0.37 (0.15)
TUDCAST+H8929.6 (7.4)0.26 (0.11)
TLCA30.8 (8.7)0.34 (0.11)
TLCAST+H8936.6 (3.3)0.22 (0.07)
TLCA+TUDCA31.7 (6.5)0.36 (0.22)
TLCA+TUDCAST+H8939.5 (14.0)0.32 (0.14)

  • cAMP levels and phosphorylated cAMP response-element binding protein (pCREB) levels as a readout of PKA activity were determined with an enzyme-linked immunosorbent assay and by immunoblotting, respectively, in shock-frozen liver tissue after perfusion with the bile acids TLCA (10 μmol/l) and/or TUDCA (25 μmol/l) or their carrier, dimethyl sulfoxide (DMSO; 0.1%, v/v) in the presence or absence of the potent PKC inhibitor staurosporine (ST, 10 nmol/l) and the PKA inhibitor H89 (100 nmol/l; see fig 1 and table 1). Significant reduction of pCREB, but not cAMP in the presence of H89 in control livers depicts the specificity of action of this PKA inhibitor. For details, see Materials and methods. Mean (SD) of four to five experiments, each.

  • **p<0.001 vs inhibitor-free perfusion; Student t test.