Quantification of the interactions among fatty acid, lysophosphatidylcholine, calcium, dimyristoylphosphatidylcholine vesicles, and phospholipase A2

Aggregation-inhibiting protein (AIP: Curtis & Greaves, 1965), which diminishes the adhesiveness of cells, particularly at low temperatures, is identified in the present paper as phospholipase A2 (EC. 3.1.1.4). Our reasons for this identification are because phospholipase activity parallels AIP activity on cell adhesion, and because various inhibitors and sera act in a parallel manner on adhesion in the presence of AIP or phospholipase. We suggest that the enzyme acts on adhesion by producing lysolecithin and other lysolipids in the plasmalemma. Addition of lysolipids diminishes cell adhesion in a manner similar to phospholipase A. Incubation of cells in Hanks' medium at 37 degrees C has a parallel effect. Conditions which would be expected to stimulate reacylation of lysolipids in the plasmalemma, i.e. incubation of cells in the external presence of CoA, ATP and a fatty acid, lead to a recovery or maintenance of adhesion after or during Hanks' incubation at 37 degrees C. All these results suggest that lipid components of the cell, probably in the plasmalemma, are of importance in adhesion. The results are discussed in relation to the long-standing controversy about the effects of low temperatures and trypsinization on cell adhesion, for phospholipase treatment of cells affects adhesion in a manner similar to trypsinization.

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Long-Chain Fatty Acid Transport at the Blood-Brain Barrier and Incorporation into Brain Phospholipids: A New In Vivo Method for Examining Neuroplasticity, and Brain Second Messenger Systems Involving Phospholipase A2 Activation

New Concepts of a Blood—Brain Barrier ◽

10.1007/978-1-4899-1054-7_13 ◽

1995 ◽

pp. 119-140 ◽

Cited By ~ 4

Author(s):

S. I. Rapoport ◽

P. J. Robinson

Keyword(s):

Fatty Acid ◽

Phospholipase A2 ◽

Blood Brain Barrier ◽

Second Messenger ◽

Chain Fatty Acid ◽

Fatty Acid Transport ◽

Acid Transport ◽

Long Chain Fatty Acid ◽

Long Chain

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Effect of chronic ethanol administration on energy metabolism and phospholipase A2 activity in rat liver

Biochemical Journal ◽

10.1042/bj1780023 ◽

1979 ◽

Vol 178 (1) ◽

pp. 23-33 ◽

Cited By ~ 52

Author(s):

P I Spach ◽

J W Parce ◽

C C Cunningham

Keyword(s):

Fatty Acid ◽

Phospholipase A2 ◽

Phospholipid Fatty Acid ◽

Respiratory Control ◽

Liver Mitochondria ◽

Liquid Diet ◽

Male Rats ◽

Ethanol Administration ◽

Phospholipid Fatty Acid Composition ◽

Apparent Lack

1. For a period of 31 days male rats were given a liquid diet containing 36% of its energy as ethanol. Liver mitochondria from these animals demonstrated lowered respiratory control with succinate as substrate, a diminished energy-linked anilinonaphthalene-sulphonic acid fluorescence response, and lowered endogenous ATP concentrations. The phospholipid/protein ratio in mitochondria from these animals was unchanged; only minor alterations in the phospholipid fatty acid composition were observed. 2. In experiments where mitochondria were incubated at 18 degrees C in iso-osmotic sucrose (aging experiments), the above energy-linked properties were lost at an earlier time in organelles from ethanol-fed animals. Phospholipase A2 acitivty was depressed in mitochondria from control animals until respiratory control was lost and ATP was depleted. In contrast, no lag in the expression of phospholipase activity was observed in mitochondria from ethanol-fed rats. This loss of control of the phospholipase resulted in an earlier degradation of membrane phospholipids under the conditions of the aging experiments. 3. The ATPase (adenosine triphosphatase) activities, measured in freshly prepared tightly coupled mitochondria and in organelles uncoupled with carbonyl cyanide p-trifluoromethoxyphenylhydrazone, were not significantly different in ethanol-fed and liquid-diet control animals. When the mitochondria were aged at 18 degrees C, the activity increased with time of incubation in organelles from both groups of animals. A lag was observed, however, as the ATPase activity increased in control preparations. This lag was not present as APTase activity increased in mitochondria from ethanol-fed animals. 4. The significantly lowered values observed for energy-linked functions with succinate as an energy source demonstrate that ethanol elicits an alteration in liver mitochondria that affects the site II-site III regions of the oxidative-phosphorylation system. The apparent lack of control of the phospholipase A2 and ATPase activities in mitochondria from ethanol-fed animals suggests that the membrane microenvironment of these enzymes has been altered such that they can exert their catabolic effects more readily under conditions of mild perturbation. The fatty acid analyses demonstrate that the observed alterations both in the energy-linked functions and in control of the phospholipase and ATPase are not mediated through changes in the acyl chain composition of bulk-phase phospholipids.

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Formation of Prostaglandin Cyclo-Peroxides and Prostaglandins by Phospholipase A2 in Platelets of Normal and Essential Fatty Acid Deficient Rats

10.1055/s-0039-1680762 ◽

1977 ◽

Author(s):

J.E. Vincent ◽

F.J. Zijlstra

Keyword(s):

Fatty Acid ◽

Platelet Aggregation ◽

Phospholipase A2 ◽

Essential Fatty Acid ◽

Essential Fatty Acid Deficient ◽

Incubation Periods ◽

Rat Platelets

Phospholipase A2 has a biphasic action upon rat platelet aggregation, enhancing after shorter and inhibiting after longer incubation periods. The first effect is inhibited by indomethacin.Cycloperoxides and thromboxane-like substances and prostaglandins are formed on incubation with the enzyme in the same amounts whether aggregation is induced or not. Formation of cycloperoxides and thromboxanes is not leading to aggregation. Phospholipase A2 enhances the aggregation of the platelets of essential fatty acid deficient rats. Only very small amounts of cycloperoxides and thromboxane-like substances are formed. It is concluded that cycloperoxides and thromboxanes can enhance, but not induce aggregation in rat platelets.

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