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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied modulation of the transient outward current in single canine Purkinje cells that were voltage clamped under Ca2+-free conditions using the patch pipette. The current showed two exponential time constants of inactivation (48, 352 ms at +58 mV and 53, 325 ms at +78 mV). Norepinephrine or isoproterenol modified the inactivation kinetics of this current without affecting the activation kinetics. The half maximum dose for norepinephrine effect was 1.9 x 10(-8) M and the effect was saturated at 10(-6) M. Norepinephrine or isoproterenol reduced the amplitude of the fast time constant component of inactivation, while increasing the amplitude of the slow component, without changing their time constants. They also increased the amplitude of a time-independent current component. The beta-antagonist, sotalol, blocked the norepinephrine effect on the transient outward current. On the other hand, both activation of adenyl cyclase by forskolin and increase of intracellular cAMP concentration produced the same effect as exposure to norepinephrine. Intracellular perfusion with the catalytic subunit of the cAMP-activated protein kinase reproduced the modulation of the current. These results suggest a role for neurotransmitter regulation of the transient outward current in cardiac cells, perhaps by channel phosphorylation.
J Mol Cell Cardiol 1989 Feb
PMID:Modulation of the cardiac transient outward current by catecholamines. 247 37

1. 3H-gamma-Aminobutyric acid (GABA) release elicited by a depolarizing K+ stimulus or by noradrenergic transmitter was examined in rat pineals in vitro. 2. The release of 3H-GABA was detectable at a 20 mM K+ concentration in medium and increased steadily up to 80 mM K+. 3. In a Ca2+-free medium 3H-GABA release elicited by 30 mM K+, but not that elicited by 50 mM K+, became blunted. 4. Norepinephrine (NE; 10(-6)-10(-4) M) stimulated 3H-GABA release from rat pineal explants in a dose-dependent manner. 5. The activity of 10(-5) M NE on pineal GABA release was suppressed by equimolecular amounts of prazosin or phentolamine (alpha 1- and alpha 1/alpha 2-adrenoceptor blockers, respectively) and was unaffected by propranolol (beta-adrenoceptor blocker). 6. The alpha 1-adrenoceptor agonist phenylephrine (10(-7)-10(-5) M) and the beta-adrenoceptor agonist isoproterenol (10(-5) M) mimicked the GABA releasing activity of NE, while 10(-7) M isoproterenol failed to affect it; the alpha 2-adrenoceptor agonist clonidine (10(-7)-10(-5) M) did not modify 3H-GABA release. 7. The addition of 10(-4) M GABA or of the GABA transaminase inhibitor gamma-acetylenic GABA or aminooxyacetic acid inhibited the melatonin content and/or release to the medium in rat pineal organotypic cultures. 8. GABA at concentrations of 10(-5) M or greater partially inhibited the NE-induced increase in melatonin production by pineal explants. 9. The depressant effect of GABA on melatonin production was inhibited by the GABA type A receptor antagonist bicuculline; bicuculline alone increased the pineal melatonin content. Baclofen, a GABA type B receptor agonist, did not affect the pineal melatonin content or release. 10. The decrease in serotonin (5-HT) content of rat pineal explants brought about by NE was not modified by GABA; GABA by itself increased 5-HT levels. 11. These results indicate that (a) GABA is released from rat pineals by a depolarizing stimulus of K+ through a mechanism which is partially Ca2+ dependent; (b) NE releases rat pineal GABA via interaction with alpha 1-adrenoceptors; (c) GABA inhibits melatonin production in vitro via interaction with GABA type A receptor sites; and (d) GABA's effect on NE-induced melatonin release does not correlate with the lack of effect on the NE-induced decrease in pineal 5-HT content.
Cell Mol Neurobiol 1989 Jun
PMID:Release and effect of gamma-aminobutyric acid (GABA) on rat pineal melatonin production in vitro. 247 90

Representative total DNA libraries of Bac. thuringiensis var. kurstaki (strain Dipel) and galleriae (strain 11-67) have been constructed on the basis of phasmid vector lambda pSL5. Recombinant phasmid clones, carrying delta-endotoxin-coding genes of both subspecies have been isolated by means of immunoenzyme screening. Restriction mapping and partial nucleotide sequence determination have demonstrated that phasmid lambda pOC2, isolated from var. kurstaki DNA library, contains the complete delta-endotoxin-coding gene, identical to the one, described by Schnepf H.E. et al. J. Biol. Chem. 1985. V. 260. P. 6264. Recombinant phasmids lambda pOC10 and 11 have been shown to contain the full-sized gene, coding delta-endotoxin of Bac. thuringiensis var. galleriae. The protein products of the cloned genes have been characterized by Western-blot analysis and bioassays. The absence of substantial homology of two genes, evidenced by Southern-blot hybridisation, correlates with sufficiently big differences in biological specificity of the corresponding proteins. This is in accordance with our previous data on N-terminal amino acid sequence determination of delta-endotoxins of those subspecies of Bac. thuringiensis.
Mol Biol (Mosk)
PMID:[Cloning and comparative characteristics of genes coding two structurally distant delta-endotoxins of Bacillus thuringiensis var. galleriae and kurstaki]. 254 94

A model of the beta 2-adrenergic receptor binding site is built from the primary structure of the receptor, experimental evidence for key binding residues and analogy with a homologous protein of partially determined structure. It is suggested that residues Trp-109, Thr-110 and Asp-113 are involved in ligand binding. Noradrenaline is successfully docked into this model, and the results of an INDO molecular orbital calculation on the complex indicate that a charge transfer interaction between Trp-109 and noradrenaline is possible.
J Comput Aided Mol Des 1989 Sep
PMID:A molecular modelling study of the interaction of noradrenaline with the beta 2-adrenergic receptor. 255 49

1. The pineal gland is regulated primarily by photoperiodic information attaining the organ through a multisynaptic pathway initiated in the retina and the retinohypothalamic tract. 2. Norepinephrine (NE) released from superior cervical ganglion (SCG) neurons that provide sympathetic innervation to the pineal acts through alpha1- and beta 1- adrenoceptors to stimulate melatonin synthesis and release. 3. The increase in cyclic AMP mediated by beta 1-adrenergic activation is potentiated by the increase in Ca2+ flux, inositol phospholipid turnover, and prostaglandin and leukotriene synthesis produced by alpha 1-adrenergic activation. 4. Central pinealopetal connections may also participate in pineal control mechanisms; transmitters and modulators in these pathways include several neuropeptides, amino acids such as gamma-aminobutyric acid (GABA) and glutamate, and biogenic amines such as serotonin, acetylcholine, and dopamine. 5. Secondary regulatory signals for pineal secretory activity are several hormones that act on receptors sites on pineal cells or at any stage of the neuronal pinealopetal pathway.
Cell Mol Neurobiol 1987 Dec
PMID:Cellular and molecular mechanisms controlling melatonin release by mammalian pineal glands. 289 78

Smooth lipopolysaccharide (sLPS) of Brucella abortus was prepared and fractionated by a modification of the procedures of Moreno et al. (J. Bac. 138:361-369, 1979). Washed B. abortus cells were disrupted by 21 freeze-quick thaw cycles with ultrasonication to separate the non-membrane-bound material. Ultrasonicated bacteria were used for preparation of membrane-bound sLPS (approximately f5, the main crude sLPS fraction described by Moreno et al.). Phenol extraction was repeated 3 times and then washed with H2O 10 times to remove most of the chromogen, polysaccharides and nucleic acids, eliminating the need for enzyme treatment as described previously. The membrane-bound sLPS was fractionated into 3 to 5 groups according to the extent of dialysis and centrifugation, these fractions required only 80 ng for positive ELISA, about 0.2 ng for positive Limulus lysate tests, and reacted well with precipitating antibodies in the serum from a strain 2308 infected cow. They had marked differences in precipitin curves and chemical composition. The protein content varied from 16% to 42% as determined by dye binding test and 17 to 60% by Lowry phenol method using bovine serum albumin as the standard, which implies that the proteins associated with LPS may also play important roles in the complex for the immunochemical interactions and the heterogeneity of B. abortus lipopolysaccharide protein complex. As compared with previous reports, a higher yield of sLPS, ranging from 3.6% to 7.7% of dried bacteria, was obtained. Group f5A, which had a standard bell shaped curve in the precipitin assay, is one of the major fractions in all three strains (1119.3, 19 and 2308). The amount of other subfractions obtained varied with batches or strains of B. abortus. These results provide a new profile of the immunochemical reactivities and the heterogeneity on B. abortus smooth membrane-bound endotoxins.
Mol Cell Biochem 1987 Jun
PMID:Immunochemical and partial chemical characterization of fractions of membrane-bound smooth lipopolysaccharide-protein complex from Brucella abortus. 311 18

A new technique for transformation of naturally noncompetent strains of Bac. cereus is proposed. Penetration of the DNA into recipient cells is based on two-step effect. At the first step of the process bacilli are affected by glycine in the early logarithmic phase of growth of the common periodic culture. At the second step the mixed DNA and recipient cells are frozen-thawed. The process permits the transforming DNA penetration via the outer membrane layer of the recipient cells having the affected permeability under the conditions of keeping bacillar recipient cells intact. The efficiency of transformation of Bac. cereus by the plasmids pUB110 and pBC16 DNA by the proposed technique is 1.10(4) and 3.10(3) of transformants per 1 mkg of the plasmid DNA.
Mol Gen Mikrobiol Virusol 1988 Nov
PMID:[Glycine-dependent cryotransformation of Bacillus cereus by plasmid DNA]. 314 60

Delayed afterdepolarizations and triggered activity occur in atrial cells of the canine coronary sinus in response to catecholamines. We studied the properties of the membrane current that causes the afterdepolarizations with the two-microelectrode voltage clamp technique in small preparations (about 0.5 x 1 mm). At a holding potential of -50 mV a transient inward current (TI) occurred after repolarization from a depolarizing step to between -40 and -20 mV in the absence of catecholamines. When the depolarizing pulse was made more positive or its duration increased the amplitude of the TI current increased and it reached peak amplitude faster. The current-voltage relationship of the TI current was studied by changing the voltage to which the membrane was repolarized after a depolarizing clamp pulse of fixed amplitude and duration. At repolarization levels positive to -30 mV there were current fluctuations without a distinct TI current. As the repolarization voltage was made more negative, a TI current occurred and its time to peak increased monotonically. The TI current amplitude increased and reached a maximum amplitude at around -60 to -70 mV, and then declined at more negative repolarization voltages. Norepinephrine increased the TI current while simultaneously augmenting the slow inward current. Elevating [Ca]0 increased the TI current amplitude. Caffeine (2 mM) increased the TI current amplitude, while caffeine (4 mM) increased and then decreased the current amplitude. The dependence of the TI current on the voltage and duration of the activating depolarizing step in these atrial cells are qualitatively similar to those of the TI current associated with digitalis toxicity in Purkinje fibers and ventricular muscle, although there are some quantitative differences. There is no distinct TI reversal in these atrial cells, similar to TI in ventricular muscle but dissimilar to TI in Purkinje fibers.
J Mol Cell Cardiol 1987 Nov
PMID:Characteristics of a transient inward current that causes delayed afterdepolarizations in atrial cells of the canine coronary sinus. 343 61

Ablation of premigratory trunk neural crest over somites 10 through 20 gives rise to chick hearts which lack sympathetic innervation. Norepinephrine, the neurotransmitter of the postganglionic sympathetic nerves, increases the rate of formation of cyclic AMP (cAMP) in cells. Cyclic AMP the modulator of certain key enzymes of metabolism, was decreased in sympathetically-aneural hearts. Six histochemical assays were used to investigate the metabolic profile of sympathetically aneural hearts as compared to control hearts. NADH-tetrazolium reductase activity (indicator of oxidative metabolism), glyceraldehyde 3-phosphate dehydrogenase activity (indicator of glycolytic rate), beta-hydroxybutyrate dehydrogenase (indicator of beta-oxidation of fatty acids), and oil red 0 assay (neutral lipid content) each demonstrated no difference between aneural and control hearts. Periodic acid-Schiff method for glycogen content, indicated greater stores of glycogen in aneural hearts compared to controls. alpha-Glucan phosphorylase, an enzyme responsible for glycogen hydrolysis, showed less activity in aneural hearts than in controls. The results indicate that the sympathetically aneural heart's metabolism is altered by decreased capability in the maximal rate of glycogen breakdown (decreased phosphorylase Vmax) and subsequent increased storage of the glycogen substrate. Enzymes of other energy transformation pathways were unaltered in the absence of sympathetic nerves.
J Mol Cell Cardiol 1987 Apr
PMID:Carbohydrate, lipid and oxidative metabolism in the sympathetically aneural chick heart. 361 18

Regional ventricular norepinephrine and myosin heavy chain concentrations were measured in two models of healed left ventricular myocardial infarction in cats. One model was characterized by a well-defined dense transmural scar (discrete myocardial infarction), while the other demonstrated a pattern of nontransmural diffuse patchy fibrosis in the infarct area (diffuse myocardial infarction). Norepinephrine and myosin heavy chain concentrations were measured in the scarred area, the non-infarcted zone surrounding the scar(s), and in sites remote from the scar. Corresponding tissue sites from unoperated animals and sham operated animals served as controls. Myosin heavy chain concentration was used as an index of surviving muscle mass to express norepinephrine concentration. Norepinephrine concentration, as a function of crude tissue mass, was significantly reduced in both the scarred tissues and the non-scarred tissues surrounding the scar in the discrete infarction model but was significantly reduced only in non-scarred tissues adjacent to the dense scar when expressed as a function of myosin heavy chain. The heavily scarred area of the discrete preparation approached normal values when corrected for myosin heavy chain content. The diffuse infarct preparation demonstrated normal norepinephrine concentration at all three sites studied, whether expressed as a function of tissue mass or myosin heavy chain. These data indicate a long-term regional reduction in norepinephrine concentration specific to non-infarcted tissues adjacent to a dense transmural myocardial infarction scar. This regional reduction in norepinephrine concentration corresponds to reported regions of increased sensitivity to sympathetic nerve stimulation in the discrete myocardial infarction model.
J Mol Cell Cardiol 1986 Apr
PMID:Regional reduction in ventricular norepinephrine after healing of experimental myocardial infarction in cats. 371 51


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