Expression of cytochrome P450-4A isoforms in the rat cremaster muscle microcirculation.

Objective: This study sought to identify any specific cytochrome P450 (CYP450) -4A enzyme isoforms expressed in arterioles and/or the surrounding parenchymal tissue of the rat cremaster muscle.
Methods: RT-PCR was used to detect the presence of specific CYP450-4A isoforms in isolated muscle fibers and arterioles from the cremaster muscle of Sprague-Dawley rats; CYP450-4A protein expression was determined by Western blotting.
Results: CYP450-4A3 mRNA was expressed in isolated muscle fibers and in cremasteric arterioles, while CYP450-4A8 mRNA was expressed only in cremasteric arterioles. CYP450-4A1 and CYP450-4A2 mRNA were not expressed in arterioles and skeletal muscle cells, although all four isoforms were strongly expressed in the liver. CYP450-4A protein was detected in both the isolated muscle fibers and in the isolated arterioles.
Conclusions: The present study identifies the specific pattern of cytochrome P450-4A isoform expression in arterioles and parenchymal cells of the skeletal muscle microcirculation, and supports the hypothesis that the cytochrome P-450 enzymes may play a role in the regulation of microvascular function in the skeletal muscle microcirculation.