scholarly journals Net activity of phospholipase A2 in brain and the lack of stimulation of the phospholipase A2-acylation stem

1977 ◽  
Vol 164 (1) ◽  
pp. 287-288
Author(s):  
C E Rowe
Keyword(s):  
Cerebral Cortex ◽  
Cyclic Amp ◽  
Guinea Pig ◽  
Phospholipase A2 ◽  
Synaptic Membranes ◽  
Rapid Hydrolysis ◽  
Hydrolysis Of ◽  
Stimulation Of

Certain observations reported previously from this laboratory have not proved reproducible. These are (1) the relatively rapid hydrolysis of added phosphatidylcholine by phospholipase A2 of tissue from the cerebral cortex of the guinea pig and (2) the stimulation by 10 micron-noradrenaline and by 1.0nM-cyclic AMP of the phospholipase A2-acylation system of isolated synaptic membranes.

scholarly journals The stimulation of the phospholipase A2-acylation system of synaptic membranes of brain by cyclic nucleotides

1975 ◽  
Vol 148 (3) ◽  
pp. 567-581 ◽  
Author(s):  
R J Gullis ◽  
C E Rowe
Keyword(s):  
Cyclic Amp ◽  
Phospholipase A2 ◽  
Cyclic Nucleotides ◽  
Membrane Lipid ◽  
Synaptic Membranes ◽  
Choline Glycerophospholipids ◽  
Hydrolysis Of ◽  
Cyclic Ump ◽  
Cyclic Cmp ◽  
Stimulation Of

Hydrolysis of phosphatidylcholine by phospholipase A2 of synaptic membranes i n Tris-CHl buffer was stimulated by cyclic AMP, cyclic GMP, cyclic CMP, cyclic UMP and adenosine (0.1 mm). In the presence of 1 mm-NaF and cofactors, the same cyclic nucleotides and adenosine (10 mm) stimulated the incorporation of added oleate into the choline glycerophospholipids of synaptic membranes. Cyclic AMP and noradrenaline stimulated the incorporation of added oleate into position 2 of choline glycerophospholipid. Stimulation of net acylation was increased by preincubation in conditions which stimulated hydrolysis of phosphatidylcholine. Cyclic AMP only slightly stimulated the transfer of oleate from oleoyl-CoA into choline glycerophospholipid. The optimum concentration of CaCl2 for the stimulation of hydrolysis by phospholipase A2 by cyclic AMP was 1 mum. Stimulation of the incorporation of added oleate was maximal in the CaCl2 concentration range 1 mum-1mm. MgCl2 also enhanced stimulations, maximum effects being obtained with concentrations of 10 mum and 0.5 mm for hydrolysis by phospholipase A2 and incorporation of added oleate respectively. ATP enhanced the stimulation of incorporation of oleate but had no effect on the cyclic nucleotide stimulation of hydrolysis of added phosphatidylcholine by phospholipase A2. Adenosine, guanosine, ADP and 5′-AMP (all at 1 mm) inhibited the stimulation of incorporation of oleate by cyclic nucleotides and inhibited the transfer of oleate from oleoyl-CoA to phospholipid. They did not inhibit the stimulation of hydrolysis of added phosphatidylcholine (by phospholipase A2) by cyclic nucleotides, but inhibited the stimulation by noradrenaline, acetylcholine, 5-hydroxytryptamine, dopamine (3,4-dihydroxyphenethylamine) and histamine. Preincubation of synaptic membranes in the water or buffer increased the net activity of phospholipase A2. Preincubation with a mixture of ATP and MgCl2 increased the initial rate of acylation of membrane lipid.

scholarly journals Turnover of protein-bound serine phosphate in respiring slices of guinea-pig cerebral cortex. Effects of putative transmitters, tetrodotoxin and other agents

1973 ◽  
Vol 132 (3) ◽  
pp. 475-482 ◽  
Author(s):  
Martin Reddington ◽  
Richard Rodnight ◽  
Michael Williams
Keyword(s):  
Cerebral Cortex ◽  
Cyclic Amp ◽  
Guinea Pig ◽  
Electrical Pulses ◽  
Phosphorus Turnover ◽  
Serine Phosphate ◽  
Stimulation Of

1. The effect of various agents on the turnover of protein-bound phosphorus in respiring slices of cerebral cortex was studied. 2. Confirming previous work turnover was increased by the application of electrical pulses for 10s to the tissue. 3. Turnover was also increased by exposure of the slices for 10min to noradrenaline (0.5mm), 5-hydroxytryptamine (1μm) and histamine (0.1mm). 4. When slices were stimulated by electrical pulses in the presence of histamine the increase in turnover was the sum of the responses given by each agent above, suggesting that different phosphorylating systems were involved. 5. Tetrodotoxin (0.5μm) blocked the increased turnover due to electrical pulses, but not that due to histamine. Tetrodotoxin also prevented the increase in tissue cyclic AMP content caused by the application of electrical pulses. 6. Phosphoprotein turnover was not affected by adenosine, despite the increase in tissue cyclic AMP content given by this agent. 7. Adenosine blocked the phosphoprotein response to histamine, but did not affect the response to electrical pulses. 8. The results are discussed in relation to the hypothesis that the stimulation of protein phosphorus turnover by electrical pulses is secondary to the release of cyclic AMP in the tissue.

scholarly journals Stimulation of the production of unesterified fatty acids in nerve endings of guinea-pig brain in vitro by noradrenaline and 5-hydroxytryptamine

1972 ◽  
Vol 126 (3) ◽  
pp. 575-585 ◽  
Author(s):  
C. J. Price ◽  
C. E. Rowe
Keyword(s):  
Fatty Acids ◽  
Cerebral Cortex ◽  
Guinea Pig ◽  
Synaptic Vesicles ◽  
Nerve Endings ◽  
Synaptic Membranes ◽  
Pig Brain ◽  
Guinea Pig Brain ◽  
Stimulation Of

1. Noradrenaline (1mm) and 5-hydroxytryptamine (1mm) stimulated the production of unesterified palmitate, oleate, stearate and arachidonate in nerve endings (synaptosomes) isolated from combined guinea-pig cerebral cortex and cerebellum. 2. Iproniazid phosphate (0.36mm) increased the concentrations of the same acids in osmotically ruptured synaptosomes. Further addition of 1mm-noradrenaline or 1mm-5-hydroxytryptamine reversed this increase. 3. Noradrenaline (0.01mm) stimulated the production of unesterified fatty acids in isolated synaptic membranes. 5-Hydroxytryptamine (0.01mm) stimulated the production of unesterified fatty acids in synaptic membranes and synaptic vesicles.

scholarly journals The stimulation by transmitter substances and putative transmitter substances of the net activity of phospholipase A2 of synaptic membranes of cortex of guinea-pig brain

1975 ◽  
Vol 148 (2) ◽  
pp. 197-208 ◽  
Author(s):  
R J Gullis ◽  
C E Rowe
Keyword(s):  
Guinea Pig ◽  
Phospholipase A2 ◽  
Synaptic Vesicles ◽  
Optimum Concentration ◽  
Synaptic Membranes ◽  
Phospholipase A1 ◽  
Response Curves ◽  
Pig Brain ◽  
Hydrolysis Of ◽  
Guinea Pig Brain

1. The distribution of the hydrolyses of phosphatidylcholine by phospholipase A2 and phospholipase A1, and the hydrolysis of lysophosphatidylcholine by lysophospholipase, in subcellular and subsynaptosomal fractions of cerebral cortices of guinea-pig brain, was determined. 2. Noradrenaline stimulated hydrolysis by phospholipase A2 in whole synaptosomes, synaptic membranes and fractions containing synaptic vesicles. 3. Stimulation of hydrolysis by phospholipase A2 in synaptic membranes by noradrenaline was enhanced by CaCl2, and by a mixture of ATP and MgCl2. The optimum concentration of CaCl2, in the presence of ATP and MgCl2, for stimulation by 10 muM-noradrenaline was in the range 1-10muM. The optimum concentration for ATP-2MgCl2 in the presence of 1 muM-CaCl2 was in the range 0.1-1mM. 4. Hydrolysis by phospholipase A2 of synaptic membranes was also stimulated by acetylcholine, carbamoylcholine, 5-hydroxytryptamine, dopamine (3,4-dihydroxyphenethylamine), histamine, psi-aminobutyric acid, glutamic acid and aspartic acid. With appropriate concentrations of cofactors, sigmoidal dose-response curves were obtained, half-maximum stimulations being obtained with concentrations of stimulant in the range 0.1-1muM. 5. Taurine also stimulated hydrolysis of phosphatidylcholine by phospholipase A2. There were only slight stimulations with methylamine, ethylenediamine or spermidine. No stimulation was obtained with glucagon.

Hydrocortisone inhibits mucin secretion from guinea pig gallbladder

1984 ◽  
Vol 247 (4) ◽  
pp. G427-G431 ◽  
Author(s):  
J. R. Moore ◽  
B. S. Turner ◽  
J. T. LaMont
Keyword(s):  
Guinea Pig ◽  
Phospholipase A2 ◽  
Sodium Succinate ◽  
Inhibitory Effect ◽  
Membrane Phospholipids ◽  
Mucin Secretion ◽  
Basal Secretion ◽  
Prostaglandin Release ◽  
Hydrolysis Of

We studied the effects of hydrocortisone, an inhibitor of phospholipase A2, on the secretion of mucin and release of prostaglandins from guinea pig gallbladder explants. We measured mucin using [3H]glucosamine as a precursor and prostaglandins by radioimmunoassay of 6-keto-prostaglandin F1 alpha. Mucin secretion and prostaglandin release were studied under basal conditions and after arachidonate stimulation. Hydrocortisone sodium succinate reversibly inhibited basal secretion of mucin by 24% at 10(-5) M (P less than 0.05 compared with control) and 34% at 10(-4) M (P less than 0.01). Hydrocortisone, 10(-4) M, also reversibly inhibited arachidonate-stimulated secretion of mucin (P less than 0.01 compared with controls incubated with arachidonate alone). Release of prostaglandin F1 alpha was significantly inhibited by hydrocortisone under basal (P less than 0.01) and arachidonate-stimulated (P less than 0.01) conditions. The inhibitory effect of hydrocortisone was mediated by inhibition of hydrolysis of arachidonate from membrane phospholipids, suggesting that exogenous arachidonate is incorporated into membrane phospholipids prior to conversion to prostaglandins.

scholarly journals The catabolism of plasmenylcholine in the guinea pig heart

1986 ◽  
Vol 236 (2) ◽  
pp. 475-480 ◽  
Author(s):  
G Arthur ◽  
L Page ◽  
T Mock ◽  
P C Choy
Keyword(s):  
Guinea Pig ◽  
Phospholipase A2 ◽  
High Specificity ◽  
Experimental Conditions ◽  
Ph Optimum ◽  
Major Pathway ◽  
Guinea Pig Heart ◽  
Mitochondrial Fractions ◽  
Wide Range ◽  
Hydrolysis Of

The hydrolysis of the alkenyl bonds of plasmenylcholine and plasmenylethanolamine by plasmalogenase, followed by hydrolysis of the resultant lysophospholipid by lysophospholipase, has been postulated as the major pathway for the catabolism of these plasmalogens. However, the postulation was based solely on the presence of plasmalogenase activity towards plasmenylethanolamine and plasmenylcholine in the brain. In this study we have demonstrated the absence of plasmalogenase activity for plasmenylcholine in the guinea pig heart under a wide range of experimental conditions. Plasmenylcholine was hydrolysed by phospolipase A2 activities in cardiac microsomal, mitochondrial and cytosolic fractions. Phospholipase A2 activities in these fractions had an alkaline pH optimum and were enhanced by Ca2+. The enzymes also displayed high specificity for plasmenylcholine with linoleoyl or oleoyl at the C-2 position. Lysoplasmalogenase activity for lysoplasmenycholine was also detected and characterized in the microsomal and mitochondrial fractions. Since the cardiac plasmalogenase is only active towards plasmenylethanolamine but not plasmenylcholine, the catabolism of these two plasmalogens must be different from each other. We postulate that the major pathway for the catabolism of plasmenycholine involves the hydrolysis of the C-2 fatty acid by phospholipase A2, and hydrolysis of the vinyl ether group of the resultant lysoplasmenylcholine by lysoplasmalogenase.

Cyclic AMP and cyclic GMP independent stimulation of ventricular calcium current by peroxynitrite donors in guinea pig myocytes

2003 ◽  
Vol 197 (2) ◽  
pp. 284-296 ◽  
Author(s):  
Daniela Malan ◽  
Renzo Cesare Levi ◽  
Giuseppe Alloatti ◽  
Andrea Marcantoni ◽  
Ivano Bedendi ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Guinea Pig ◽  
Cyclic Gmp ◽  
Calcium Current ◽  
Stimulation Of
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