Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The change of cytosolic Ca2+ concentration ([Ca2+]i) caused by vasopressin was examined in indo-1-loaded A7r5 smooth muscle cells by use of the high-performance laser cytometer and ratiometric fluorescence method. Vasopressin (100 nM) caused an initial rapid rise and a delayed increase in [Ca2+]i (n = 6). However, in the presence of tetraethylammonium chloride (10 mM), vasopressin consistently triggered sustained Ca2+ oscillations which were preceded by a large peak of [Ca2+]i. The latency for the development of this huge increase in [Ca2+]i prior to the occurrence of sustained Ca2+ oscillations was always the same. The frequency and amplitude of this type of Ca2+ oscillation varied depending upon the extracellular Ca2+ concentration. Ca(2+)-free solution did not completely suppress the sustained Ca2+ oscillations, but caffeine (20 mM) effectively abolished them. The present findings indicate that in A7r5 smooth muscle cells, the sustained Ca2+ oscillations triggered by vasopressin in the presence of tetraethylammonium chloride were mainly due to Ca2+ release from IP3-sensitive Ca2+ stores and Ca2+ influx from extracellular space, and did not require the pacemaker activity derived from the surface membrane. Moreover, the vasopressin-induced change in [Ca2+]i appeared to be linked to pertussis toxin-insensitive GTP-binding protein(s).
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PMID:Induction of Ca2+ oscillations by vasopressin in the presence of tetraethylammonium chloride in cultured vascular smooth muscle cells. 760 17

Vasopressin (AVP), the antidiuretic hormone, is a cyclic nonapeptide that acts through binding to G protein-coupled specific membrane receptors pharmacologically divided into three subtypes (V1a, V1b, and V2) linked to distinct second messengers. Within the family of human AVP receptors, the V2 AVP receptor has been cloned, but the structure of the human V1a and V1b AVP receptors remains unknown. We report here the structure and functional expression of a human V1a AVP receptor complementary DNA isolated from human liver cDNA libraries. Cloning and sequencing of a full-length clone isolated a 1472-nucleotide sequence encoding a 418-amino acid polypeptide with seven putative transmembrane domains typical of G protein-coupled receptors. Amino acid sequence identity with the rat liver V1a AVP receptor, the human and rat V2 AVP receptors, and the human oxytocin receptor was 72, 36, 37, and 45%, respectively. Functional characterization of the cloned receptor was done by transient expression in COS-7 cells and stable expression in Chinese hamster ovary cells. Localization of the expressed receptor at the cellular surface was illustrated by using the fluorescent linear analog phenylacetyl-D-Tyr(Et)-Phe-Gln-Asn-Lys-Pro-Arg-NH2 coupled to fluorescein-avidin by dodecabiotin. Competition binding experiments with phenylacetyl-D-Tyr(Et)-Phe-Val-Asn-Lys-Pro-[125I]Tyr-NH2 and AVP analogs revealed high affinity specific binding sites of the V1a subtype. Saturation binding experiments with [3H]AVP confirmed the presence of a single class of high affinity binding sites. Measurement of AVP-induced inositol phosphate production and calcium mobilization confirmed that the expressed V1a AVP receptor is coupled to phospholipase C via a pertussis toxin-insensitive pathway. Thus, the human V1a AVP receptor belongs to the superfamily of seven-transmembrane segment receptors with a significant sequence identity with the other members of the AVP-oxytocin family of receptors.
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PMID:Molecular cloning, sequencing, and functional expression of a cDNA encoding the human V1a vasopressin receptor. 810 69

The roles of heterotrimeric GTP-binding regulatory proteins (G-proteins) and inositol polyphosphates in the mechanism by which vasopressin stimulates Ca2+ inflow in hepatocytes were investigated by using single cells loaded with fura2 by microinjection. Vasopressin-stimulated Ca2+ inflow was mimicked by microinjection of guanosine 5'-[gamma-thio]triphosphate (GTP[S]) or guanosine 5'-[beta gamma-imido]triphosphate to the cells, but not adenosine 5'-[gamma-thio]triphosphate (ATP[S]) or guanosine 5'-[beta-thio]diphosphate (GDP[S]). Extracellular Gd3+ (5 microM) inhibited both vasopressin- and GTP[S]-stimulated Ca2+ inflow. GDP[S], but not GMP, administered to hepatocytes by microinjection, completely inhibited vasopressin-stimulated Ca2+ inflow and partially inhibited vasopressin-induced release of Ca2+ from intracellular stores. The microinjection of pertussis toxin had no effect either on the release of Ca2+ from intracellular stores or on Ca2+ inflow induced by vasopressin, but completely inhibited changes in these processes induced by epidermal growth factor (EGF). Hepatocytes isolated from rats treated with pertussis toxin for 24 h exhibited no vasopressin- or GTP[S]-stimulated Ca2+ inflow, whereas the vasopressin-stimulated release of Ca2+ from intracellular stores was similar to that observed for control cells. Heparin or ATP[S] inhibited, or delayed the onset of, both vasopressin-induced release of Ca2+ from intracellular stores and vasopressin-stimulated Ca2+ inflow. Vasopressin-induced oscillations in intracellular [Ca2+] were observed in some heparin-treated cells. It is concluded that the stimulation by vasopressin of Ca2+ inflow to hepatocytes requires inositol 1,4,5-trisphosphate (InsP3) and, by implication, the pertussis-toxin-insensitive G-protein required for the activation of phospholipase C beta [Taylor, Chae, Rhee and Exton (1991) Nature (London) 350, 516-518], and another G-protein which is slowly ADP-ribosylated by pertussis toxin and acts between InsP3 and the putative plasma-membrane Ca2+ channel. EGF-stimulated Ca2+ inflow involves at least one G-protein which is rapidly ADP-ribosylated and is most likely required for InsP3 formation.
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PMID:A slowly ADP-ribosylated pertussis-toxin-sensitive GTP-binding regulatory protein is required for vasopressin-stimulated Ca2+ inflow in hepatocytes. 817

We previously reported that pertussis toxin (PTX) had little effect on arginine vasopressin-induced formation of inositol trisphosphate (IP3) in rat aortic smooth muscle cells [Kondo et al.: Biochemical and Biophysical Research Communications 161:677-682, 1989]. In the present study, we investigated the mechanism of vasopressin-induced arachidonic acid release in rat aortic smooth muscle cells. Vasopressin stimulated both the release of arachidonic acid and the formation of IP3 dose dependently in the range between 10 pM and 1 microM. The effect of vasopressin on arachidonic acid release was more potent than that on the formation of IP3. Quinacrine, a phospholipase A2 inhibitor, significantly suppressed the vasopressin-induced arachidonic acid release but had little effect on the formation of inositol phosphates. NaF, a GTP-binding protein activator, mimicked vasopressin by stimulating the arachidonic acid release. The arachidonic acid release stimulated by a combination of vasopressin and NaF was not additive. PTX partially but significantly suppressed the vasopressin-induced arachidonic acid release. In the cell membranes, PTX catalyzed ADP-ribosylation of a protein with an M(r) of about 40,000. Pretreatment of membranes with 0.1 microM vasopressin in the presence of 2.5 mM MgCl2 and 100 microM GTP markedly attenuated this PTX-catalyzed ADP-ribosylation of the protein in a time-dependent manner. These results strongly suggest that PTX-sensitive GTP-binding protein is involved in the coupling of vasopressin receptor to phospholipase A2 in primary cultured rat aortic smooth muscle cells.
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PMID:Vasopressin induces arachidonic acid release through pertussis toxin-sensitive GTP-binding protein in aortic smooth muscle cells: independence from phosphoinositide hydrolysis. 822 89

Vasopressin stimulated GSH efflux from Hep G2 cells. The maximal effect was observed at 10nM. Pretreatment with pertussis toxin or cholera toxin for 18 hr increased GSH efflux. Vasopressin-mediated GSH efflux was observed even in the cells pretreated with those compounds. Dibutyryl-cAMP or dibutyryl-cGMP enhanced GSH efflux although an additive effect of vasopressin was not observed. Glucagon and a phorbol ester independently increased GSH efflux while both compounds decreased the effect of vasopressin. Staurosporine, an inhibitor of protein kinase C, inhibited vasopressin-mediated GSH efflux. The effect of vasopressin was observed even in the absence of extracellular Ca2+. Vasopressin stimulates GSH efflux from Hep G2 cells and protein kinase C-dependent pathway may play a significant role in vasopressin-mediated GSH efflux.
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PMID:Characterization of vasopressin-mediated GSH efflux from Hep G2 cells: significance of protein kinase C. 845 Jul 14

Vasopressin is the key regulator of water homeostasis in vertebrates. Central to its antidiuretic action in mammals is the redistribution of the water channel aquaporin 2 (AQP2) from intracellular vesicles to the apical membrane of kidney epithelial cells, an event initiated by an increase in cAMP and activation of protein kinase A. The subsequent steps of the signaling cascade are not known. To identify proteins involved in the AQP2 shuttle we exploited a recently developed cell line (CD8) derived from the rabbit cortical collecting duct and stably transfected with rat AQP2 cDNA. Treatment of CD8 cells with pertussis toxin (PTX) inhibited both the vasopressin-induced increase in water permeability and the redistribution of AQP2 from an intracellular compartment to the apical membrane. ADP-ribosylation studies revealed the presence of at least two major PTX substrates. Correspondingly, two alpha subunits of PTX-sensitive G proteins, Galphai2 and Galphai3, were identified by Western blotting. Introduction of a synthetic peptide corresponding to the C terminus of the Gi3 alpha subunit into permeabilized CD8 cells efficiently inhibited the cAMP-induced AQP2 translocation; a peptide corresponding to the alpha subunits of Gi1/2 was much less potent. Thus a member of the Gi family, most likely Gi3, is involved in the cAMP-triggered targeting of AQP2-bearing vesicles to the apical membrane of kidney epithelial cells.
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PMID:A heterotrimeric G protein of the Gi family is required for cAMP-triggered trafficking of aquaporin 2 in kidney epithelial cells. 971 91

In this study, the presence of Na(+)-permeable cation channels was determined and characterized in LLC-PK1 cells, a renal tubular epithelial cell line with proximal tubule characteristics derived from pig kidney. Patch-clamp analysis under cell-attached conditions indicated the presence of spontaneously active Na(+)-permeable cation channels. The channels displayed nonrectifying single channel conductance of 11 pS, substates, and an approximately 3:1 Na(+)/K(+) permeability-selectivity ratio. The Na(+)-permeable cation channels were inhibited by pertussis toxin and reactivated by G protein agonists. Cation channel activity was observed in quiescent cell-attached patches after vasopressin stimulation. The addition of protein kinase A and ATP to excised patches also induced Na(+) channel activity. Spontaneous and vasopressin-induced Na(+) channel activity were inhibited by extracellular amiloride. To begin assessing potential molecular candidates for this cation channel, both reverse transcription-PCR and immunocytochemical analyses were conducted in LLC-PK1 cells. Expression of porcine orthologs of the alphaENaC and ApxL genes were found in LLC-PK1 cells. The expression of both gene products was confirmed by immunocytochemical analysis. Although alphaENaC labeling was mostly intracellular, ApxL labeled to both the apical membrane and cytoplasmic compartments of subconfluent LLC-PK1 cells. Vasopressin stimulation had no effect on alphaENaC immunolabeling but modified the cellular distribution of ApxL, consistent with an increased membrane-associated ApxL. The data indicate that proximal tubular LLC-PK1 renal epithelial cells express amiloride-sensitive, Na(+)-permeable cation channels, which are regulated by the cAMP pathway, and G proteins. This channel activity may implicate previously reported epithelial channel proteins, although this will require further experimentation. The evidence provides new clues as to potentially relevant Na(+) transport mechanisms in the mammalian proximal nephron.
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PMID:Characterization of Na+-permeable cation channels in LLC-PK1 renal epithelial cells. 1498 25


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