Membrane-cytoskeleton dynamics in rat parietal cells: mobilization of actin and spectrin upon stimulation of gastric acid secretion.

The gastric parietal (oxyntic) cell is presented as a model for studying the dynamic assembly of the skeletal infrastructure of cell membranes. A monoclonal antibody directed to a 95-kD antigen of acid-secreting membranes of rat parietal cells was characterized as a tracer of the membrane movement occurring under physiological stimuli. The membrane rearrangement was followed by immunocytochemistry both at the light and electron microscopic level on semithin and thin frozen sections from resting and stimulated rat gastric mucosa.

[Vasopressin, oxytocin and angiotensin receptors in mammals].

The synthesis of new radiolabelled compounds and the evolution of the techniques designed to study the hormonal receptors allow a better understanding of their properties. Three types of vasopressin receptors have been described: the V1a receptor of liver and blood vessels, the V1b receptor of hypophysis and the V2 receptor of kidney. Such a classification was based on two criteria: The structure of the binding site and the nature of the second messenger produced.

A marker of acid-secreting membrane movement in rat gastric parietal cells.

A monoclonal antibody (mab 146.14) marker of the movement of acid-secreting membranes in rat gastric parital cells has been produced and characterized. Mab 146.

Properties of membranous phospholipase C from WRK1 cell: sensitivity to guanylnucleotides and bacterial toxins.

As previously described, WRK1 plasma membrane possesses a vasopressin-sensitive phospholipase C [G. Guillon et al., 1986, FEBS Lett.

An endogenous ligand for the central sulfonylurea receptor.

An endogenous ligand for the rat central sulfonylurea receptor has been evidenced in the rat central nervous system. The characteristics of this ligand (extractibility, non-dialysability, chromatographic behaviour on different media, sensitivity to proteases) indicate that it is a neutral to slightly basic peptide.

Oxyntomodulin and glicentin: brain-gut peptides in the rat.

Glucagon-like materials and glucagon have been identified by immunoassay and immunocytochemistry in the mammalian central nervous system. However, the molecular forms relevant to brain glucagon-like immunoreactivity (GLI) have not been precisely defined. In the rat small intestine, more than 90% of GLI is constituted by two peptides: oxyntomodulin (OXM) and glicentin.

Complex interactions of agonists with alpha 1-adrenoceptors in intact cells.

1. The apparent Ki values of (-)-noradrenaline (NA), (+)- and (-)-adrenaline (Ad), phenylephrine and the mono-fluorinated NAs (in position 2, 5 or 6) for alpha 1-adrenoceptors of intact BC3H1 cells labelled with [3H]-prazosin were greatly dependent on the incubation temperature. 2.

A nonclassical 5-hydroxytryptamine receptor positively coupled with adenylate cyclase in the central nervous system.

A nonclassical 5-hydroxytryptamine (5-HT) receptor mediates the stimulation of adenylate cyclase activity in mouse embryo colliculi neurons in primary culture. The pharmacological profile characterized with agonists and antagonists suggests that this 5-HT receptor does not appear to correspond to a known 5-HT receptor. On this 5-HT receptor, 5-HT (EC50 = 109 +/- 17 nM) and 5-methoxytryptamine (5-MeOT) were equipotent agonists.

NMDA receptors activate the arachidonic acid cascade system in striatal neurons.

Receptors for excitatory amino-acid transmitters on nerve cells fall into two main categories associated with non-selective cationic channels, the NMDA (N-methyl-D-aspartate) and non-NMDA (kainate and quisqualate) receptors. Special properties of NMDA receptors such as their voltage-dependent blockade by Mg2+ (refs 3, 4) and their permeability to Na+, K+ as well as to Ca2+ (refs 5, 6), have led to the suggestion that these receptors are important in plasticity during development and learning. They have been implicated in long-term potentiation (LTP), a model for the study of the cellular mechanisms of learning.

G-proteins in skeletal muscle. Evidence for a 40 kDa pertussis-toxin substrate in purified transverse tubules.

In muscle, it has been established that guanosine 5'-[gamma-thio]triphosphate (GTP[S]), a non-hydrolysable GTP analogue, elicits a rise in tension in chemically skinned fibres, and that pretreatment with Bordetella pertussis toxin (PTX) decreases GTP[S]-induced tension development [Di Virgilio, Salviati, Pozzan & Volpe (1986) EMBO J. 5, 259-262]. In the present study, G-proteins were analysed by PTX-catalysed ADP-ribosylation and by immunoblotting experiments at cellular and subcellular levels.

Development of an oxyntomodulin/glicentin C-terminal radioimmunoassay using a "thiol-maleoyl" coupling method for preparing the immunogen.

Oxyntomodulin (OXM) and glicentin, two peptides processed from proglucagon, both contain the glucagon sequence and a C-terminal basic octapeptide, KRNRNNIA extension. A method to produce antibodies, directed specifically toward the C-terminal extension of these two peptides, was developed; it consisted of the use of thioled bovine serum albumin conjugated with the synthetic N-maleoyl C-terminal octapeptide as the immunogen. Three rabbits (FAN, LEG, and PIP) generated antisera with affinity constants close to 5 X 10(10) M-1.

Cholera-toxin and corticotropin modulation of inositol phosphate accumulation induced by vasopressin and angiotensin II in rat glomerulosa cells.

Vasopressin (VP) and angiotensin II (AT II) stimulate the production of inositol phosphates (IP) in rat glomerulosa cells. Guanosine 5'-[gamma-thio]triphosphate (GTP[S]), but not VP or AT II, stimulates IP production in a myo-[3H]inositol-prelabelled glomerulosa-cell membrane preparation. In combination with GTP[S], these hormones potentiate the response to GTP[S], indicating the existence of a G-protein involved in the coupling of the VP and AT II receptor with the phospholipase C.

5-HT1B receptors are negatively coupled with adenylate cyclase in rat substantia nigra.

We measured the inhibition of forskolin-stimulated adenylate cyclase by 5-hydroxytryptamine (5-HT) and other serotonin agonists in rat substantia nigra homogenates. 5-HT, 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)indole (RU 24969), 5-carboxamidotryptamine (5-CT), 1-(m-trifluoromethyl-phenyl)piperazine (TFMPP) and tryptamine inhibited forskolin-stimulated adenylate cyclase with EC50 of 67, 40, 83, 100 and 200 nM respectively. 8-Hydroxydipropylaminotetralin (8-OH-DPAT) and ipsapirone, both 5-HT1A-selective drugs, were respectively weak and ineffective to inhibit forskolin-stimulated adenylate cyclase.

Peptides mimicking the flap of human renin: synthesis, conformation, and antibody recognition.

Four peptides related to human renin flap region have been synthesized. Two of them are ring closed through appropriately designed disulfide bridges. Structure analysis involving IR and NMR techniques and recognition by polyclonal human renin antibodies provides support for a beta-hairpin secondary structure of the cyclized peptides identical with that presented by the flap section in the speculative human renin model [Blundell, T.

Multiple species and isoforms of Bordetella pertussis toxin substrates.

In purified G proteins from bovine brain cortex the ADP-ribosylated substrates of Bordetella pertussis toxin (PT) can be resolved in three polypeptides by polyacrylamide gel electrophoresis: a 39 kDa major substrate, corresponding to Go alpha and two others (40 and 41 kDa) assigned to alpha subunits of Gi-like proteins. These three polypeptides were also detected in membranes of normal cells or tissues from neuronal and endocrine origins. In contrast, in membranes from other origins, only two PT substrates at 41 and 40 kDa were resolved; the latter being the most abundant ADP-ribosylated substrate in human platelets and C6 glioma cells.

New probes for angiotensin II receptors. Synthesis, radioiodination and biological properties of biotinylated and haptenated angiotensin derivatives.

The present work delineates the basis for chemical modifications which can be introduced on the angiotensin II (AII) molecule to design probes suitable for indirect affinity techniques, especially for receptor purification. Using the solid-phase synthesis strategy, biotin or dinitrophenyl moieties have been added at the N-terminus of AII, with aminohexanoic acid as spacer arm. The resulting probes, (6-biotinylamido)hexanoyl-AII (Bio-Ahx-AII) and dinitrophenylaminohexanoyl-AII (Dnp-Ahx-AII), were prepared in their monoiodinated and highly labelled radioiodinated forms, with possible sulphoxidation of biotin.

Covalent labeling of vasopressin receptors from LLC-PK1 cells by the use of a bifunctional reagent.

The possibility of covalently attaching vasopressin to its receptors by the use of a bifunctional reagent was explored. Plasma membranes from the LLC-PK1 pig kidney cell line were purified by Percoll density gradient centrifugation. These membranes contained a single population of high affinity (Kd = 5.

125I-d(CH2)5[Tyr(Me)2, Tyr(NH2)9]AVP: iodination and binding characteristics of a vasopressin receptor ligand.

A radioiodinated vasopressin antagonist, d(CH2)5[Tyr(NH2)9]AVP has been prepared. Iodination was carried out at the phenyl moiety of the tyrosylamide residue at position 9, followed by HPLC purification. Non-radiolabelled monoiodinated antagonist was used as a reference for identification.

125I-labelled d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH2(9)]OVT: a selective oxytocin receptor ligand.

An oxytocic antagonist, [1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid,2-O-methyltyrosine,4-threonine, 8-ornithine,9-tyrosylamide]vasotocin (d(CH2)5[Tyr(Me)2, Thr4,Tyr-NH2(9)]OVT [corrected], was monoiodinated at the phenyl moiety of the tyrosylamide residue at position 9. 125I-labelling was performed with 1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenyl-glycoluril. Iodination resulted in an increased affinity for rat uterine oxytocin receptors.

Immunocytochemical localization of the guanine nucleotide-binding protein Go in primary cultures of neuronal and glial cells.

We have localized the guanine nucleotide-binding protein, Go, in primary cultures of pure neuronal and glial cells prepared from different mouse brain areas. Immunoblotting experiments with selective affinity-purified polyclonal rabbit antibodies to the 39 kDa alpha subunit of Go (Go alpha) indicated that Go is distributed in both neurons and glial cells. Go alpha accounts for 0.

Pharmacology of 5-hydroxytryptamine-1A receptors which inhibit cAMP production in hippocampal and cortical neurons in primary culture.

Serotonin (5-hydroxytryptamine, 5-HT) inhibited the formation of cAMP promoted by vasoactive intestinal polypeptide, plus forskolin, in mouse hippocampal and cortical neurons in primary culture. The rank order of potencies of classical 5-HT1 agonists in inhibiting cAMP formation in hippocampal neurons was 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) greater than 5-carboxamidotryptamine (5-CT) greater than d-lysergic acid diethylamide greater than 5-HT greater than 5-methoxy-N,N-dimethyltryptamine (5-MeO-N,N-DMT) greater than RU 24969 greater than ipsapirone greater than bufotenine greater than buspirone [half-maximal efficacy (EC50) = 7, 18, 30, 52, 90, 102, 100, 110, and 128 nM, respectively]. All the tryptamine derivatives substituted in position 5 of the indol were potent agonists [5-HT, 5-CT, 5-MeO-N,N-DMT, 5-methoxytryptamine, and bufotenine], whereas tryptamine, N-methyltryptamine, and N,N-dimethyltryptamine were poor agonists.

A new quisqualate receptor subtype (sAA(2)) responsible for the glutamate-induced inositol phosphate formation in rat brain synaptoneurosomes.

Inositol phosphate synthesis elicited by excitatory amino acids was measured in rat forebrain synaptoneurosomes in presence of Li(+). Quisqualate (QA) was the most potent excitatory amino acid inducing inositol phosphate formation. This QA action was not blocked by any of the usual antagonists [glutamate-amino-methyl-sulphonate (GAMS); glutamate-diethyl-ester (GDEE); ?-d-glutamyl-glycine (?-DGG)] known to inhibit the QA-induced depolarization.