Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9882275 | Archives of Biochemistry and Biophysics | 2005 | 9 Pages |
Abstract
Phospholipase D (PLD2) produces phosphatidic acid (PA), which is converted to 1,2 diacylglycerol (DAG) by phosphatidate phosphohydrolase (PAP2). Since PA and DAG regulate Ca2+ movements, we examined PLD2 and PAP2 in the sarcolemma (SL) and sarcoplasmic reticular (SR) membranes from hearts subjected to ischemia and reperfusion (I-R). Although SL and SR PLD2 activities were unaltered after 30Â min ischemia, 5Â min reperfusion resulted in a 36% increase in SL PLD2 activity, whereas 30Â min reperfusion resulted in a 30% decrease in SL PLD2 activity, as compared to the control value. SR PLD2 activity was decreased (39%) after 5Â min reperfusion, but returned to control levels after 30Â min reperfusion. Ischemia for 60Â min resulted in depressed SL and SR PLD2 activities, characterized with reduced Vmax and increased Km values, which were not reversed during reperfusion. Although the SL PAP2 activity was decreased (31%) during ischemia and at 30Â min reperfusion (28%), the SR PAP2 activity was unchanged after 30Â min ischemia, but was decreased after 5Â min reperfusion (25%) and almost completely recovered after 30Â min reperfusion. A 60Â min period of ischemia followed by reperfusion caused an irreversible depression of SL and SR PAP2 activities. Our results indicate that I-R induced cardiac dysfunction is associated with subcellular changes in PLD2 and PAP2 activities.
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Authors
Girma Asemu, Melissa R. Dent, Tushi Singal, Naranjan S. Dhalla, Paramjit S. Tappia,