Increased skeletal muscle expression of PKC-θ but not PKC-α mRNA in type 2 diabetes: inverse relationship with in-vivo insulin sensitivity

BACKGROUND Increases in PKC-theta (the major isoenzymic form of PKC in skeletal muscle) protein and isozyme activity have been reported in skeletal muscle from patients with type 2 diabetes mellitus (T2DM) and dietary-induced rodent models of insulin resistance, but the underlying biochemical mechanism is unclear and muscle PKC-theta mRNA expression has not been previously reported in patients with T2DM or in relation to in-vivo measurements of insulin sensitivity. METHODS Diet-only treated patients with T2DM (n=7) and healthy nondiabetic controls (n=7) of similar BMI attended the clinical research unit on two occasions, 1 week apart, for a skeletal muscle biopsy 2 h after a 75-g oral glucose load and measurement of whole-body insulin sensitivity using the euglycaemic hyperinsulinaemic clamp. RESULTS Type 2 DM patients were insulin resistant (M-value 3.0 +/- 0.4 vs. 8.6 +/- 0.8 mg glucose kg(-1) min(-1)) with fasting hyperinsulinaemia (306 +/- 116 vs. 34 +/- 9 pmol L(-1), P