Deinhibition of cardiac Na/sup +/-K/sup +/-ATPase after exposure to exogenous phospholipase A/sub 2/
After 2 h of exogenous phospholipase A/sub 2/ (PLA/sub 2/) exposure, membrane phospholipid decreased from 3.22 +/- 0.31 to 1.06 +/- 0.13 ..mu..mol/mg (33% of control). All classes of phospholipid, except sphingomyelin, were hydrolyzed, whereas total cholesterol content was unaffected. Increases in nonesterified fatty acids (NEFA) were reflected primarily in oleic (18:1), linoleic (18:2), and arachidonic (20:4). Na/sup +/-K/sup +/-adenosinetriphosphatase (ATPase) activity was inhibited to 29% of control by 2 h of PLA/sub 2/ treatment, and this inhibition was reversed (albeit, not completely after 5 min of PLA/sub 2/ treatment) by removal of the hydrolysis products with 0.1% bovine serum albumin (BSA). In contrast, the apparent binding capacity for (/sup 3/H)ouabain was not affected by PLA/sub 2/ treatment. Unmasking of latent (/sup 3/H)ouabain binding by alamethicin was utilized to estimate changes in the proportion of sealed vesicles present before and after PLA/sub 2/ treatment. PLA/sub 2/ treatment resulted in a time-dependent loss of sealed vesicles that paralleled the time course of phospholipid hydrolysis and was not reversed by washing with BSA. These studies demonstrate that cardiac Na/sup +/-K/sup +/-ATPase activity is inhibited by accumulation of endogenously produced lysophospholipids and NEFA. In contrast, loss of vesicle integrity may result from both accumulation of endogenously produced hydrolysis products and membrane phospholipid depletion.
- Research Organization:
- Univ. of Connecticut Health Center, Farmington
- OSTI ID:
- 6470290
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 252:1
- Country of Publication:
- United States
- Language:
- English
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ATP-ASE
BIOCHEMISTRY
LIPASE
OUABAIN
UPTAKE
TRITIUM COMPOUNDS
DOGS
HEART
INHIBITION
ISCHEMIA
MYOCARDIUM
PHOSPHOLIPIDS
SARCOPLASMIC RETICULUM
ACID ANHYDRASES
ANIMALS
BODY
CARBOHYDRATES
CARBOXYLESTERASES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CARDIOVASCULAR DISEASES
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CHEMISTRY
DISEASES
DRUGS
ENZYMES
ESTERASES
ESTERS
GLYCOSIDES
HYDROLASES
LABELLED COMPOUNDS
LIPIDS
MAMMALS
MUSCLES
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANOIDS
ORGANS
PHOSPHOHYDROLASES
STROPHANTHINS
VASCULAR DISEASES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques