Stimulation of Hydrolysis of Phosphatidic Acid by Cholinergic Agents in Guinea Pig Synaptosomes

Adenine nucleotides of guinea-pig neocortical tissues were labelled by incubation with [14C]adenine and excess of adenine was then removed by superfusion with precursor-free medium. Adenine derivatives released from the tissue during continued superfusion, including a period of electrical stimulation of the tissue, were collected by adsorption and examined after elution and concentration. The stimulation greatly increased the 14C output, and material collected during and just after stimulation had a u.v. spectrum which indicated adenosine to be a major component. The additional presence of inosine and hypoxanthine was shown by chromatography and adenosine was identified also by using adenosine deaminase. Total adenine derivatives released from the tissue during a 10min period of stimulation were obtained as hypoxanthine, after deamination and hydrolysis of adenosine and inosine, and amounted to 159nmol/g of tissue. This corresponded to the release of approx. 7pmol/g of tissue per applied stimulus. The hypoxanthine sample derived from superfusate hypoxanthine, inosine and adenosine was of similar specific radioactivity to the sample of inosine separated chromatographically, and each was of higher specific radioactivity than the adenine nucleotides obtained by cold-acid extraction of the tissue.

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Inhibition of phosphatidylinositol synthesis and the inactivation of calcium entry after prolonged exposure of the blowfly salivary gland to 5-hydroxytryptamine

Biochemical Journal ◽

10.1042/bj1780059 ◽

1979 ◽

Vol 178 (1) ◽

pp. 59-69 ◽

Cited By ~ 129

Author(s):

M J Berridge ◽

J N Fain

Keyword(s):

Salivary Gland ◽

Phosphatidic Acid ◽

Salivary Glands ◽

Calcium Transport ◽

Prolonged Exposure ◽

Calcium Entry ◽

Ionophore A23187 ◽

Hydrolysis Of ◽

External Calcium ◽

Stimulation Of

The incorporation of [32P]Pi into all salivary-gland phospholipids except phosphatidic acid was inhibited by 5-hydroxytryptamine. The accumulation of [32P]Pi into phosphatidic acid was actually enhanced by 5-hydroxytryptamine. There was an inhibition of labelled inositol incorporation into phosphatidylinositol by 5-hydroxytryptamine, which seems to be mediated by calcium because it was mimicked by the ionophore A23187, but was prevented if glands were stimulated with 5-hydroxytryptamine in the absence of external calcium. Inhibition of synthesis together with stimulation of breakdown will decrease the concentration of phosphatidylinositol, which could account for the inactivation of calcium transport observed at high 5-hydroxytryptamine concentrations. When salivary glands were stimulated with 1 micrometer-5-hydroxytryptamine, there was a rapid increase in the transfer of 45Ca2+ from the medium into the saliva, but with time this transport declined to a low value. If the glands were washed free of 5-hydroxytryptamine and incubated in the presence of 2mM-inositol for 1 h, the increase in calcium transport caused by 5-hydroxytryptamine was restored. There was little recovery in the absence of inositol. If glands were stimulated with 5-hydroxytryptamine in the absence of external calcium, a condition which prevents the inhibition of phosphatidylinositol synthesis, calcium transport in response to 5-hydroxytryptamine was greater than in glands preincubated with 5-hydroxytryptamine in the presence of calcium. The inactivation of calcium transport may result from a decrease in phosphatidylinositol concentration. These results support the hypothesis that the hydrolysis of phosphatidylinositol plays some role in either the opening or closing of calcium ‘gates’.

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Acetylcholine stimulates hydrolysis of 32P-labeled phosphatidic acid in guinea pig synaptosomes

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(73)91335-1 ◽

1973 ◽

Vol 50 (3) ◽

pp. 934-941 ◽

Cited By ~ 35

Author(s):

Jochen Schacht ◽

Bernard W. Agranoff

Keyword(s):

Guinea Pig ◽

Phosphatidic Acid ◽

Hydrolysis Of

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Stimulation of phospholipase D activity and phosphatidic acid production by norepinephrine in rat aorta

AJP Cell Physiology ◽

10.1152/ajpcell.1993.264.3.c609 ◽

1993 ◽

Vol 264 (3) ◽

pp. C609-C616 ◽

Cited By ~ 23

Author(s):

A. W. Jones ◽

S. D. Shukla ◽

B. B. Geisbuhler

Keyword(s):

Phosphatidic Acid ◽

Phospholipase D ◽

Time Course ◽

Rat Aorta ◽

Functional Responses ◽

Phosphatidylinositol Bisphosphate ◽

Phosphatidylinositol Phosphate ◽

Transphosphatidylation Reaction ◽

Hydrolysis Of ◽

Stimulation Of

We sought to relate norepinephrine (NE) stimulation of phosphatidic acid (PA) production to functional responses of rat aorta and pathways for PA production. The time course for changes in PA was closely related to Ca-dependent tonic responses in 42K efflux and contraction. NE (30 microM for 1 min) increased PA and reduced phosphatidylcholine (PC) and phosphatidylinositol (PI) based on Pi analyses and 32P labeling of phospholipids. The 32P-to-Pi ratio in PA (0.8 +/- 0.2, n = 13) was similar to PC (0.8 +/- 0.1, n = 14) but was significantly lower (P < 0.001) than PI (4.6 +/- 0.5, n = 14). The 32P-to-Pi ratio in PA was also lower (P < 0.02) than phosphatidylinositol phosphate and phosphatidylinositol bisphosphate. NE also increased [3H]PA twofold (P < 0.05) when PC was selectively labeled with [3H]myristic acid. These observations are more consistent with PA being formed from the hydrolysis of PC by phospholipase D (PLD) than by the phosphorylation of diacylglycerol produced by the action of phospholipase C. PLD was assayed by the formation of phosphatidylethanol (PEt) via a transphosphatidylation reaction with ethanol (half-maximal stimulation at 0.4-0.5% vol/vol). The time course for PLD stimulation by NE was similar to PA, with significant increases (P < 0.002) during 10 s to 30 min exposure. Once formed, PEt was degraded slowly, with a half time > 3 h. It is concluded that NE stimulates PLD in rat aorta, which forms a significant amount of PA from the hydrolysis of PC.(ABSTRACT TRUNCATED AT 250 WORDS)

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Effects of hormones on Na and H2O transport and on phospholipid metabolism in toad bladder

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1964.206.1.136 ◽

1964 ◽

Vol 206 (1) ◽

pp. 136-142 ◽

Cited By ~ 4

Author(s):

Sarah Hestrin-Lerner ◽

Lowell E. Hokin

Keyword(s):

Phosphatidic Acid ◽

Sodium Transport ◽

Phosphatidyl Choline ◽

Phosphatidyl Ethanolamine ◽

Phosphatidyl Inositol ◽

Phospholipid Metabolism ◽

Significant Inhibition ◽

Toad Bladder ◽

Cholinergic Agents ◽

Stimulation Of

Incubation of tied paired lobes of bladder from Bufo marinus with 0.025–0.25 U/ml of oxytocin led to appreciable stimulations of both sodium transport and of water transport from the mucosal (luminal) to serosal side. Incubation with aldosterone led to a very slight stimulation of sodium transport, which was statistically significant, in one out of three series. P32 from orthophosphate was incorporated into phosphatidic acid, phosphatidyl ethanolamine, phosphatidyl choline, and phosphatidyl inositol. There were no statistically significant stimulations in the incorporation of P32 into phosphatidic acid, phosphatidyl choline, or phosphatidyl inositol at any concentration of oxytocin. However, there was a statistically significant stimulation of P32 incorporation into phosphatidyl ethanolamine with 0.025 U/ml oxytocin. There was a statistically significant inhibition in incorporation in phosphatidyl choline and phosphatidyl inositol with 0.25 U/ml oxytocin. Cholinergic agents did not produce statistically significant stimulations of either water or sodium transport in toad or turtle bladders, but they led to significant stimulations of incorporation of P32 into some of the phosphatides (phosphatidic acid, phosphatidyl choline, and phosphatidyl inositol in the toad bladder, and phosphatidic acid and phosphatidyl inositol in turtle bladder). On the basis of the fine structure of the epithelium of the toad bladder it is suggested that the phospholipid effect in response to cholinergic agents may be related to stimulation of the secretion of an organic material by the epithelial and/or goblet cells.

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

Biochemical Journal ◽

10.1042/bj1640287 ◽

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.

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Biosynthesis of Mitochondrial Phospholipids Using Endogenously Generated Diglycerides

Canadian Journal of Biochemistry ◽

10.1139/o75-106 ◽

1975 ◽

Vol 53 (7) ◽

pp. 784-795 ◽

Cited By ~ 23

Author(s):

W. C. McMurray

Keyword(s):

Endoplasmic Reticulum ◽

Phosphatidic Acid ◽

Phospholipase C ◽

Rat Liver ◽

De Novo ◽

Liver Mitochondria ◽

Rat Liver Mitochondria ◽

Isolated Mitochondria ◽

Hydrolysis Of ◽

Stimulation Of

When isolated mitochondria or microsomes from rat liver were treated with phospholipase C, the incorporation of radioactive phospholipid precursors was markedly enhanced, presumably as a result of production of diglycerides by hydrolysis of endogenous phospholipids. Incorporation of CDP[14C]choline into lecithin in rat liver or BHK-21 mitochondria could be attributed to residual contamination from elements of the endoplasmic reticulum, with added diglycerides or with endogenous diglycerides produced by the phospholipase C treatment. A similar stimulation of [γ32P]ATP incorporation into phospholipids was observed with exogenous or endogenous diglycerides, but the mitochondrial diglyceride kinase in either case was also related to the degree of microsomal contaminants. It was concluded that previous studies showing negligible capacity of mitochondria for lecithin biosynthesis de novo were not explainable on the basis of limited accessibility of added diglycerides, and that formation of phosphatidic acid by diglyceride kinase was not of significance in rat liver mitochondria.

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Evidence for receptor and G-protein regulation of a phosphatidylethanolamine-hydrolysing phospholipase A1 in guinea-pig heart microsomes: stimulation of phospholipase A1 activity by DL-isoprenaline and guanine nucleotides

Biochemical Journal ◽

10.1042/bj3120805 ◽

1995 ◽

Vol 312 (3) ◽

pp. 805-809 ◽

Cited By ~ 5

Author(s):

K Badiani ◽

G Arthur

Keyword(s):

Guinea Pig ◽

Hydrolytic Activity ◽

Receptor Activation ◽

Phospholipase A1 ◽

Guinea Pig Heart ◽

Phospholipases A2 ◽

Adrenergic Antagonist ◽

Beta 2 ◽

Hydrolysis Of ◽

Stimulation Of

While evidence has been presented for the receptor-mediated activation of phospholipases A2, C and D, the activation of phospholipase A1 subsequent to receptor activation has not been established. Phospholipase A1-catalysed hydrolysis of 1-palmitoyl-2-linoleoyl-glycerophosphoethanolamine (GPE) by guinea-pig heart microsomes was stimulated 40-60% by isoprenaline. This isoprenaline-mediated increase in activity was blocked by propranolol and butoxamine, a specific beta 2-adrenergic antagonist, but not by atenolol, a specific beta 1-adrenergic antagonist. Neither clonidine nor phenylephrine, alpha 1- and alpha 2-adrenergic agonists respectively, had a stimulatory effect on the hydrolysis of the PE substrate. Guanosine 5′(-)[gamma-thio]triphosphate (GTP[S]) and guanosine 5′(-)[beta, gamma-imido]triphosphate, but not guanosine 5′(-)[beta-thio]diphosphate (GDP[S]) or adenosine 5′(-)[gamma-thio]triphosphate, stimulated the hydrolysis of 1-palmitoyl-2-linoleoyl-GPE by phospholipase A1. GDP[S] inhibited the isoprenaline-mediated stimulation of phospholipase A1 activity. Phospholipase A1 hydrolysis of 1-palmitoyl-2-linoleoyl-GPE was not dependent on cations; however, the stimulatory effects of isoprenaline and GTP[S] on the hydrolytic activity were abolished by cation chelators. The above data suggest that phospholipase A1 activity in guinea-pig heart microsomes is activated by the binding of isoprenaline to beta 2-adrenergic receptors. Furthermore the stimulation of phospholipase A1 activity by the agonist may be mediated via activation of G-proteins.

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Interaction of Vasopressin with Human Blood Platelets: Dependency on Mg2+

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661662 ◽

1986 ◽

Vol 56 (03) ◽

pp. 260-262 ◽

Cited By ~ 6

Author(s):

Isabella Roos ◽

Fabrizia Ferracin ◽

Alfred Pletscher

Keyword(s):

Phosphatidic Acid ◽

Human Blood ◽

Arginine Vasopressin ◽

Specific Binding ◽

Blood Platelets ◽

Bivalent Cations ◽

Platelet Membranes ◽

Maximal Rise ◽

Human Blood Platelets ◽

Stimulation Of

SummaryArginine-vasopressin (AVP) in the presence of Mg2+ but not in the absence of bivalent cations led to accumulation of [32P]-phosphatidic acid ([32P]-PA) in human blood platelets. Mg2+ also enhanced the specific binding of [3H]-AVP to intact platelets. The concentrations of the cation which enabled AVP to cause half maximal rise of [32P]-PA and those inducing half maximal [3H]-AVP-binding were of the same order. It is concluded that the stimulation of phosphatidyl inositide breakdown by AVP in presence of Mg2+ is at least partially due to a Mg2+-induced enhancement of specific AVP-binding to the platelet membranes.

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