TRANSCRIPTION RATES OF SERCA AND PHOSPHOLAMBAN GENES CHANGE IN RESPONSE TO CHRONIC STIMULATION OF SKELETAL-MUSCLE

Chronic low frequency stimulation of predominantly fast-twitch skeleta l muscles decrease the levels of SERCA1 (fast-twitch sarco(endo)plasmi c reticulum Ca2+-ATPase) mRNA, and increase the levels of SERCA2 (slow -twitch sarco(endo)plasmic reticulum Ca2+-ATPase) and phospholamban mR NAs. To assess the role of transcription in these changes in mRNA leve ls, nuclei were isolated from chronically stimulated canine latissimus dorsi muscles and transcription rates were estimated by nuclear run-o n assays. Decreases in the rates of SERCA1 gene transcription matched the fall in its mRNA level and increases in the rates of SERCA2 and ph ospholamban gene transcription matched the increases in their mRNAs. ( C) 1998 Elsevier Science B.V.