IN-SITU IDENTIFICATION OF NEURONAL NITRIC-OXIDE SYNTHASE (NOS-I) MESSENGER-RNA IN MOUSE AND RAT SKELETAL-MUSCLE

Skeletal muscle provides a major source of the signaling molecule nitr ic oxide (NO) however in situ identification of NO-synthase (NOS) mRNA has not been verified. We have used NOS-I (neuronal NOS) probes prepa red from plasmid DNA by reverse transcription-polymerase chain reactio n (RT-PCR) to detect mRNA transcripts in skeletal muscle cells and myo fibers of rat and mouse. Mouse C2C12 myoblasts and myotubes reveal str ong cytosolic in situ hybridization (ISH) signals in vitro. In adult a nimals, ISH signals are detectable in striated myofibers at subsarcole mmal and perinuclear regions whilst the myofibrillar compartment is de void of signals. Expression of NOS-I mRNA in fusion-competent myoblast s suggests that the NOS/NO system is of relevance to myogenic differen tiation. Compartmentalization of NOS-I mRNA may reflect spatiofunction al actions between NOS message and protein and the putative subcellula r NO targets. (C) 1998 Elsevier Science Ireland Ltd.