MODIFICATION OF SKELETAL-MUSCLE SARCOPLASMIC-RETICULUM FATTY ACYL COMPOSITION DURING AROUSAL FROM HIBERNATION

The fatty acyl composition of sarcoplasmic reticulum was analyzed in s keletal muscle from hibernating and aroused Richardson's ground squirr els, Spermophilus richardsonii. Total levels of monounsaturated fatty acyl groups increased in the phosphatidylcholine (PC), phosphatidyleth anolamine (PE) and phosphatidylinositol (PI) fractions of aroused anim als. Docosahexaenoic acid (22:6n-3) was lower in all phospholipids whi le the ratio 20:4/22:6 was higher in aroused animals. These changes in fatty acyl composition have the potential to alter SR Ca2(+)-ATPase a ctivity and Ca2+ uptake efficiency during the energetically demanding arousal process.