Document Detail

Myocardial calcium-independent phospholipase A2 activity during global ischemia in isolated rabbit hearts.
MedLine Citation:
PMID:  8759249     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: To study calcium-independent phospholipase A2 activity during global ischemia in isolated rabbit hearts by measuring the hydrolysis of the endogenous choline phospholipids. METHODS: Langendorff perfused rabbit hearts were exposed to global ischemia for 15 or 60 min, or control perfusion for the same length of time. The hearts were then rapidly frozen in liquid nitrogen and lyophilized. Calcium-independent phospholipase A2 activity in the lyophilized tissue was studied by measuring accumulation of lysophospholipids resulting from hydrolysis of both the choline diacylphospholipid and the choline plasmalogen pool. RESULTS: The calcium-independent phospholipase A2 activity showed the same pH, temperature and calcium sensitivity in control and ischemic (15 min of ischemia) lyophilized myocardial tissue. Incubation of control and ischemic tissue showed no difference in the rate of accumulation of lysophospholipids when the ischemic tissue was obtained from hearts exposed to 15 min of ischemia (107 +/- 4 vs 111 +/- 7 nmol/g dry wt x min, ischemia versus control, mean +/- s.e.m., n = 8), but a significant decrease was noticed in tissue from hearts that had been exposed to 60 min of ischemia (31 +/- 9 vs 86 +/- 18 nmol/g dry wt x min, P < 0.05, n = 4). The decreased phospholipase A2 activity in tissue exposed to 60 min of ischemia was not due to enhanced metabolism of the lysophospholipids (84 +/- 15 vs 79 +/- 8 nmol/g dry wt x min, n = 4). The calcium-independent phospholipase A2 activity was considerably lower in fresh myocardial tissue compared with lyophilized tissue, but comparison of control and ischemic fresh tissue gave results comparable to those found using lyophilized tissue. The myocardial calcium-independent phospholipase A2 activity showed no plasmalogen selectivity in either control or ischemic myocardium. CONCLUSIONS: In isolated perfused rabbit hearts we found no evidence for activation of calcium-independent phospholipase A2 activity during global ischemia. With prolonged time of ischemia there was a significant decrease in calcium-independent phospholipase A2 activity.
O Vesterqvist; C A Sargent; G J Grover; M L Ogletree
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Cardiovascular research     Volume:  31     ISSN:  0008-6363     ISO Abbreviation:  Cardiovasc. Res.     Publication Date:  1996 Jun 
Date Detail:
Created Date:  1996-10-11     Completed Date:  1996-10-11     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  932-40     Citation Subset:  IM    
Department of Pharmacology, Bristol-Myers Squibb Pharmaceutical Research Insititute, Princeton, NJ 08543-4000, USA.
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MeSH Terms
Calcium / metabolism
Chromatography, High Pressure Liquid
Lysophospholipids / metabolism
Myocardial Ischemia / enzymology*
Myocardium / enzymology*,  metabolism
Phospholipases A / analysis,  metabolism*
Phospholipases A2
Time Factors
Reg. No./Substance:
0/Lysophospholipids; 7440-70-2/Calcium; EC 3.1.1.-/Phospholipases A; EC A2

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