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E Costa

Publications and source records attributed to E Costa.

At least 559 records · Page 31Linked to original sources
PubMed1976

Induction of tyrosine 3-monooxygenase in adrenal medulla: role of protein kinase activation and translocation.

The transsynaptic induction of tyrosine 3-monooxygenase (TH) in rat adrenal medulla is preceded by an early increase in the ratio of cyclic adenosine monophosphate (AMP) to cyclic guanosine monophosphate, an activation of cytosol cyclic AMP-dependent protein kinase, and a subsequent translocation of protein kinase catalytic subunits from cytosol to subcellular particles. As a result of this translocation, nuclear protein kinase activity increases during the induction of TH. Transection of splanchnic nerve reverts these events and prevents the induction of TH. Thus, adrenal medulla activation and translocation of cyclic AMP-dependent protein kinase may act as a long-range messenger for the genetic regulation of TH synthesis.

Adrenal Medulla↗
PubMed1976

Enhanced template activity in chromatin from adrenal medulla after phosphorylation of chromosomal proteins.

Translocation of protein kinase to the nucleus had been implicated earlier in the transsynaptic control of gene expression mediated by cholinergic nerves in adrenal medulla. Phosphorylation of chromosomal proteins by adenosine 3',5'-monophosphate-dependent protein kinase and adenosine 3',5'-monophosphate enhances the template activity of chromatin from adrenal medulla. When homologous RNA polymerase II is used the relative activation is greater than that obtained with Escherichia coli RNA polymerase. The substrate for such phosphorylation does not seem to be RNA polymerase II. Phosphorylation of specific acidic protein probably mediates this enhancement of template activity.

Adenosine Triphosphate↗
PubMed1976

Mass fragmentographic quantitation of glutamic acid and gamma-aminobutyric acid in cerebellar nuclei and sympathetic ganglia of rats.

A method for the simultaneous quantitation of glutamic acid and gamma-aminobutyric acid (GABA) in tissue by mass fragmentography has been developed. The amino and carboxylic groups of the two amino acids were in a convenient one-step reaction derivatized with pentafluoropropionic anhydride and hexafluoroisopropanol. Deuterium-labeled glutamic acid and GABA and a homologue of GABA have been used as internal standards. The usefulness of the technique has been demonstrated by measurements in parts of rat cerebellum and in the superior cervical ganglion.

Aminobutyrates↗
PubMed1976

A kinetic analysis of the cyclic nucleotide phosphodiesterase regulation by the endogenous protein activator. A study of rat brain and frog sympathetic chain.

The effect of the endogenous protein activator on the kinetic characteristics of a highly purified, activator-deficient rat brain phosphodiesterase (EC 3.1.4.-) of a highly purified, activator-deficient rat brain phosphodiesterase (EC 3.1.4-) was studied. This enzyme preparation has only a high Km for cyclic AMP and a low Km for cyclic GMP. In the presence of 20 muM Ca2+, saturating concentrations of the activator decreased the Km of this enzyme for cyclic AMP from 350 muM to about 80 muM, without changing the V. The phosphodiesterase activator did not change the Km of phosphodiesterase for cyclic GMP; however, amoderate increase of V was seen. The activator lacks species specificity; the activator isolated from the bullfrog sympathetic chain produced the same qualitative and comparable quantitative changes in the kinetic properties of the purified rat brain phosphodiesterase. Cyclic GMP is a potent competitive inhibitor of the phosphodiesterase activation by the activator (Ki=1.8 muM), using cyclic AMP as a substrate. Cyclic AMP inhibits slightly the hydrolysis of cyclic GMP by phosphodiesterase in the presence of activator (Ki=155 muM) only.

Animals↗
PubMed1976

Association between the increase of cAMP content and the trans-synaptic induction of tyrosine hydroxylase in rat adrenal medulla. Studies with dexamethasone and reserpine.

When dexamethasone 0.25 or 2.5 mumole/kg i.p. was injected 2 h before reserpine (16 mumol/kg i.p.) the time course of the increase in cAMP content of rat adrenal medulla was changed. Reserpine alone caused a monophasic increase lasting between 1-2 h; reserpine after dexamethasone caused a biphasic increase: the immediate response, lasting between 15 and 30 min, was followed by a secondary increase beginning 2-3 h after reserpine and lasting for several hours. The overall increase in cAMP content elicited by reserpine during the 8 h following injection remained unchanged or was even increased, depending on the dose of dexamethasone. Pretreatment with dexamethasone, which delayed the increase in cAMP, also delayed the activation and translocation of protein kinase and the induction of tyrosine hydroxylase caused by reserpine in adrenal medulla. The action of reserpine on the cAMP content of adrenal medulla required an intact innervation and did not appear to be related to increased secretion of ACTH from pituitary. In denervated adrenals reserpine failed to increase the cAMP content of the medulla but not that of the cortex.

Adrenal Cortex↗
PubMed1976

Regional changes in the rate of turnover of acetylcholine in rat brain following diazepam or muscimol.

Muscimol (8.8 mumol/kg i.v.) and diazepam (7.04 mumol/kg i.p.) decreased the rate of turnover of acetylcholine in midbrain and cortex of rat brain but failed to change acetylcholine turnover in striatum and hippocampus. The similarity in the profile of the action of diazepam and muscimol on acetylcholine turnover in various brain structures adds support to the view that GABA participates in mediating the actions of diazepam. Since the striatum contains an abundance of GABA neurones and intrinsic cholinergic neurones, it is inferred that the metabolism of acetylcholine, and presumably the activity of striatal cholinergic neurones are not regulated by the activation of GABA receptors. Similar considerations apply to the cholinergic pathway projecting from the septum to the hippocampus.

Acetylcholine↗
PubMed1976

Regulation of transsynaptically elicited increase of 3':5'-cyclic AMP by endogenous phosphodiesterase activator.

Experiments with cold exposure confirmed previous studies indicating that the endogenous protein acitvator of phosphodiesterase (PDEA) isolated by Cheung participates in the in vivo regulation of 3':5'-cyclic adenosine monophosphate (cAMP) in adrenal medulla. This activator of cAMP phosphodiesterase (PDE) (3':5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17) is present in the particulate as well as the soluble fractions of rat brain. It was found that a purified cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37), in the presence of ATP and cAMP, stimulates 3-fold the release of PDEA from the particulate fraction of rat brain and adrenal medulla. The substrate for this phosphorylation could be either a membrane protein that binds PDEA or PDEA itself. In vivo evidence, however, obtained by injecting rats intraventricularly with [gamma-32P]ATP, indicates that the PDEA does not contain radioactive phosphate in its structure. Also, PDEA could not be phosphorylated by protein kinase in vitro. The following mechanism is postulated: when the intracellular content of cAMP increases it activates a protein kinase which phosphorylates a PDEA-binding membrane protein and releases PDEA. In turn this binds to activator-deficient high Km PDE and decreases its Km to facilitate the hydrolysis of the increased concentration of cAMP.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1976

Activation and nuclear translocation of protein kinase during transsynaptic induction of tyrosine 3-monooxygenase.

The tyrosine-3-monooxygenase activity [L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2] of rat adrenal medulla is induced 20-24 hr after the injection of reserpine (16 mumol/kg intraperitoneally). This and other inducing stimuli increase the 3': 5'-cyclic AMP (cAMP) content in the medulla for longer than 60 min and activate the cAMP-dependent protein kinase (ATP: protein phosphotransferase; EC 2.7.1.37) for several hours. Corticotropin (ACTH), dopamine, and propranolol do not induce the monooxygenase, but elicit an increase in the cAMP content of the medulla which fails to activate protein kinase and lasts less than 1 hr. A high- and low-molecular-weight protein kinase are separated by gel filtration from the 20,000 X g pellet extract of adrenal medulla homogenate. The activity of the low-molecular-weight enzyme is expressed as its ability to phosphorylate histone. The protein kinase activity of the pellet is increased between 3 and 17 hr after reserpine injection. Our evidence indicates that this increase is due to a translocation from cytosol to subcellular structures of a kinase that utilizes lysine-rich histone as phosphate acceptor. The protein kinase activity that is extracted from a purified nuclear fraction prepared from the adrenal medulla of rats injected 7 hr previously with reserpine is greater than that extracted from medulla of saline-treated rats.

Adrenal Medulla↗