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)

A microphysiometer was used to quantify the rate of extracellular acidification by C6 glioma cells and L fibroblasts expressing recombinant dopamine D2 receptors. The dopamine D2 receptor agonist, quinpirole, accelerated the rate of acidification of the medium by C6 cells expressing either the short or long form of D2 receptors, D2(415) and D2(444), but not by wild-type cells that were not transfected with a D2 receptor cDNA. The rate of acidification increased with increasing concentrations of quinpirole up to 100 nM. Inhibition of the response by the dopamine D2 antagonist, spiperone, provided additional evidence that the enhanced extracellular acidification resulted from stimulation of D2 receptors. To test the hypothesis that D2 receptor-stimulated extracellular acidification was due to transport of protons by a Na+/H+ antiporter and reflected intracellular alkalinization, the effect of two inhibitors of Na+/H+ exchange, amiloride and methyl-isobutyl-amiloride, was determined. Both compounds inhibited quinpirole-induced extracellular acidification at concentrations that did not alter D2 receptor-mediated inhibition of adenylylcyclase or radioligand binding to D2 receptors. In addition, quinpirole-induced extracellular acidification was greatly inhibited by removal of sodium from the extracellular medium, confirming the participation of Na+/H+ exchange in the extrusion of acid. Quinpirole (100 nM) also increased the rate of extracellular acidification by L cells expressing D2(415), LZR1 cells. Treatment with pertussis toxin (100 ng/ml for 18 h) had no effect on the quinpirole-induced acid extrusion by C6D2(415) and LZR1 cells, although the same pertussis toxin treatment regimen completely prevented inhibition of adenylylcyclase. We conclude that recombinant D2 receptors accelerate Na+/H+ exchange in C6 cells and L fibroblasts by a pathway that does not involve inhibition of adenylylcyclase or pertussis toxin-sensitive G proteins.
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PMID:Dopamine D2 receptor stimulation of Na+/H+ exchange assessed by quantification of extracellular acidification. 136 Nov 88

Pertussis toxin (PT) has previously been shown to affect a wide variety of immune responses and to cause lymphocyte proliferation. We have investigated the biochemical basis for the mitogenic activity of PT by using human peripheral blood lymphocytes. PT was found to induce a rapid rise in cytosolic free calcium concentration and an alkalinization of the cytosol through the Na+/H+ antiporter. The toxin was also found to induce expression of IL-2-receptor on CD3+ cells and to stimulate IL-2 production. PT induced proliferation of both CD4+ and CD8+ T cells in the presence (but not in the absence) of accessory cells. PT also stimulated IL-1 production by monocytes but neither IL-1, IL-6 alone nor a combination of the two lymphokines could replace accessory cells suggesting that cell:cell contact is required. Low doses of PT induced ADP-ribosylation of G proteins but this treatment did not affect significantly PHA-induced [Ca2+]i increase and IL-2-induced DNA synthesis suggesting that the substrates of the ADP-ribosyltransferase activity of PT are not involved in the signalling pathways leading to DNA replication.
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PMID:Pertussis toxin-induced mitogenesis in human T lymphocytes. 190 37

The role of protein kinase C in regulating Ca2+ channel activity was investigated using the whole-cell patch-clamp technique in the mouse pituitary tumor cell line AtT-20. The Ca2+ current was activated by depolarizing voltage steps from a holding potential of -80 mV. Extracellular application of the protein kinase C activator 1-oleoyl-2-acetylglycerol (OAG) reduced voltage-dependent Ca2+ current. This effect was reversible and dose dependent (10-100 microM). Pertussis toxin did not block the effect of OAG on Ca2+ current, suggesting that OAG does not affect Ca2+ channels via a pertussis toxin sensitive guanosine triphosphate binding protein. Na+-free solutions did not block the effect of OAG on Ca2+ channels, suggesting that this effect of OAG does not involve the Na+/H+ antiporter. The phorbol esters 12-deoxyphorbol-13-isobutyrate (10 microM) and phorbol-12,13-diacetate (100 microM) also reduced Ca2+ current. The results suggest that protein kinase C may be an inhibitory regulator of voltage-dependent Ca2+ channels.
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PMID:The protein kinase C activator 1-oleoyl-2-acetylglycerol inhibits voltage-dependent Ca2+ current in the pituitary cell line AtT-20. 244 24

The binding of interleukin 2 (IL 2) to specific cell surface receptors provides a unique proliferative stimulus to sensitive T-lymphocytes. The purpose of this investigation was to examine the hypothesis that IL 2 stimulus-response coupling in the IL 2-dependent murine T-lymphocyte clone CTLL-2 employed some of the intracellular second messengers used by other growth factors. No evidence was obtained to implicate changes in intracellular Ca2+ concentrations, protein kinase C activation, or stimulation of the Na+/H+ antiporter or the Na+/K+ ATPase as requirements for stimulation by recombinant human IL 2. Pertussis toxin did not inhibit IL 2-driven growth of CTLL-2, and while cholera toxin did inhibit growth, its effect was optimal 6 to 8 hr after addition of IL 2 and could be mimicked by increased intracellular cyclic-AMP. Thus, guanine nucleotide-binding regulatory proteins do not appear to be involved in stimulation by this lymphokine. Together, these data suggest that IL 2 may not use any of the same types of intracellular second messengers generated subsequent to the binding of antigen or mitogen by T-lymphocytes.
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PMID:Does interleukin 2 stimulus-response coupling result in generation of intracellular second messengers? 284 44

Preincubation with an alpha 2-adrenergic agonist sensitized subsequent forskolin- and vasoactive intestinal peptide-stimulated cyclic AMP production in HT29 cells, a human colonic adenocarcinoma cell line. Preincubation with somatostatin, another agonist negatively coupled to adenylate cyclase, sensitized forskolin-stimulated cyclic AMP production to a lesser extent. alpha 2-Adrenergic agonist preincubation also resulted in desensitization as indicated by a shift to the right in the dose-response curve of a subsequent challenge by an alpha 2-adrenergic agonist. In an effort to elucidate the mechanism for sensitization, we examined protein kinase C and the Na+/H+ antiporter. Whereas these components had marked effects on forskolin stimulation, there was no effect on sensitization. Changes in the concentration of extra-cellular Ca2+ or Mg2+ had no effect on either forskolin stimulation or sensitization. Pertussis toxin pretreatment caused a time-dependent decrease in sensitization, an attenuation of inhibition of cyclic AMP production, and a decrease in subsequent [32P]ADP-ribosylation by pertussis toxin. The time course for these three events was similar, implicating the inhibitory guanine nucleotide regulatory protein in the mechanism for alpha 2-adrenergic receptor-mediated sensitization of forskolin-stimulated cyclic AMP production. In addition, pertussis toxin dramatically decreased forskolin-stimulated cyclic AMP production, although with a different time course. These results suggest that the mechanism of sensitization is via an as yet undefined sequence of biochemical events that includes the inhibitory guanine nucleotide regulatory protein, but does not include inhibition of adenylate cyclase nor activation of the Na+/H+ antiporter.
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PMID:Characterization and possible mechanisms of alpha 2-adrenergic receptor-mediated sensitization of forskolin-stimulated cyclic AMP production in HT29 cells. 284 62

We stably expressed a rat D3 receptor cDNA in C6 glioma cells (C6-D3 cells), quantifying receptor expression with the radioligands [125I]epidepride (KD = 0.1 nM) and [3H]spiperone (KD = 0.7 nM). As reported previously for D2 receptors, quinpirole induced a 9-16% increase in the rate of extracellular acidification by C6-D3 cells. The acidification was inhibited by epidepride and by the Na+/H+ antiporter inhibitors, amiloride and methylisobutylamiloride, but pertussis toxin treatment had no effect on quinpirole-induced extracellular acidification. These data suggest that D3 receptor stimulation of Na+/H+ exchange in C6 glioma cells is not mediated by the pertussis toxin-sensitive G proteins, Gi or G(o). Overnight treatment of C6-D3 cells with N-propylnorapomorphine, dopamine, or quinpirole resulted in large concentration-dependent increases (up to 500%) in the density of D3 receptors on membranes prepared from the cells. Antagonists had smaller, variable effects on the density of D3 receptors in C6-D3 cells, except for domperidone, which significantly increased the density of D3 receptors. Treatment with pertussis toxin had no effect on the agonist-induced receptor up-regulation, indicating that an interaction with pertussis toxin-sensitive G proteins was not required. Densitometry analysis of Northern blots of RNA prepared from C6-D3 cells showed no significant N-propylnorapomorphine-induced increase in D3 receptor message. Treatment with cycloheximide, however, completely prevented receptor up-regulation by N-propylnorapomorphine. Pretreatment of C6-D2 cells with 10 microM DA resulted in a substantial heterologous sensitization, in which isoproterenol-stimulated adenylyl cyclase activity was enhanced more than twofold.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Regulation and functional characterization of a rat recombinant dopamine D3 receptor. 852 56

The efficacy of the antimigraine compound sumatriptan in migraine relief has been attributed to its interaction with 5-HT1B receptors in cerebral blood vessels causing cranial vasoconstriction, and/or on nerve endings of the trigeminovascular system in the dura mater inhibiting the inflammatory process by decreasing neuropeptide release. Otherwise, the metabolic effects following 5-HT1B receptor activation are largely unknown. In CHO-K1 cells expressing recombinant h5-HT1B receptors, activation of these receptors by sumatriptan and related agonists enhanced their metabolic rate by 34.9%, but not in wild-type cells. Treatment with pertussis toxin (100 ng/ml), addition of the 5-HT1B receptor antagonist GR127935 (30 nM), attenuation or substitution of the extracellular glucose supply, prevented the sumatriptan-mediated enhancement of the metabolic rate. This metabolic enhancement was also blocked by washout of extracellular Na+, independent of the blockade of the Na+/H+ antiporter by ethylisopropylamiloride. The Na(+)-dependent metabolic enhancement by sumatriptan suggests activated 5-HT1B receptors pilot cellular energy demand. This metabolic feature may contribute to the mode of action of 5-HT1B agonists in migraine relief.
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PMID:Na(+)-dependent metabolic coupling upon 5-HT1B receptor activation by sumatriptan and related agonists. 982 13

1. The operational characteristics of somatostatin (SRIF) sst4 receptors are poorly understood. In this study, we have characterized human recombinant sst4 receptors expressed in CHO cells (CHOsst4) by radioligand binding and microphysiometry. 2. Increasing concentrations SRIF or other SRIF receptor ligands inhibited specific [125I]-Tyr11-SRIF binding in CHOsst4 cell membranes with respective pIC50 values of SRIF (8.82), L-362855 (7.40), BIM-23027 (<5.5) and MK-678 (<5.5). 3. These ligands displayed agonist activity, producing concentration-dependent increases in rates of extracellular acidification (EAR) with pEC50 values of SRIF (9.6) and L-362855 (8.0), respectively. BIM-23027 and MK-678 were at least 1000 times weaker than SRIF. The SRIF maximum was about 40% of that observed with L-362855. 4. In the presence of SRIF (0.1-1 nM), concentration-effect curves to L-362855 were displaced to the right with a progressive reduction in the L-362855 maximum. 5. When cells were only exposed to a single maximally effective concentration of SRIF or L-362855, there was no difference in the magnitude of the agonist-induced increase in EAR. However, a second agonist challenge, 30 min later showed that responses to SRIF but not L-362855 were markedly desensitized. 6. When concentration-effect curves to SRIF and L-362855 were obtained by combining data from cells exposed to only a single agonist concentration, SRIF (pEC50 9.2) was approximately 20 times more potent than L-362855 (pEC50 8.0) but the maxima were the same. Responses to both SRIF and L-362855 were abolished by pertussis toxin. 7. SRIF and L-362855-induced increases in EAR were inhibited by N-ethyl isopropyl amiloride (10 microM) but were not modified by inhibitors of PKC (Go-6976), MAP kinase (PD-98059), tyrosine kinase (genistein) or tyrosine phosphatase (sodium orthovanadate). 8. The results suggest that SRIF-induced increases in EAR in CHOsst4 cells involved activation of the Na+/H+ antiporter and were mediated via Gi/Go G proteins. Responses to SRIF, but not L-362855, were subject to marked desensitization which may be a consequence of differential activation of receptor-effector coupling pathways.
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PMID:Differential agonist activity of somatostatin and L-362855 at human recombinant sst4 receptors. 983 22