Parathyroid hormone-related protein is rapidly up-regulated in blood vessels of rat skeletal muscle by low-frequency stimulation.
To identify early changes in gene expression of fast-twitch rat muscle exposed to chronic low-frequency stimulation, differential display was applied comparing mRNA patterns between control and 12-h stimulated tibialis anterior (TA) muscles. Among the signals of differentially expressed mRNAs, a cDNA of approximately 300 bp was identified as specific to the parathyroid-hormone-related protein (PTHrP). As verified by semi-quantitative reverse transcriptase polymerase chain reaction, this mRNA was present at low levels in normal slow-twitch soleus and fast-twitch TA muscles, but was approximately 80-fold elevated in TA muscles after 12 h of low-frequency stimulation. With ongoing stimulation for 2 or 4 days PTHrP mRNA returned to basal levels. PTHrP was located exclusively in blood vessels of both control and stimulated muscles. PTHrP immunohistochemistry revealed enhanced capillarization in 8-day stimulated muscles. In view of its vasodilative effect the up-regulation of PTHrP could be an important initial step related to enhanced capillarization in response to increased contractile activity.
Schneider
A G
AG
Faculty of Biology, University of Konstanz, Germany.
Leuthäuser
K
K
Pette
D
D
D000818:Animals; D001808:Blood Vessels / Q000378:metabolism*; D003001:Cloning, Molecular; D004558:Electric Stimulation; D004591:Electrophoresis, Polyacrylamide Gel; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000096:biosynthesis*; D044162:Parathyroid Hormone-Related Protein; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000502:physiology*
D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D012333:RNA, Messenger