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)

1. We have examined the effects of L-glutamate and gamma-aminobutyric acid (GABA) on the presynaptic membrane of spiny lobster by the use of intra-axonal recording near the nerve terminals. 2. Application of glutamate to the synaptic region produced hyperpolarization in the presynaptic membrane but depolarization in the postsynaptic membrane. The presynaptic glutamate potential (PGP) is generated by an activation of K+ channels, as evidenced by its dependence on external K+ concentration. 3. The PGP was not affected by a spider toxin (JSTX), which blocks the postsynaptic glutamate receptor. By contrast, pertussis toxin (IAP) effectively blocked the PGP without affecting the resting conductance channels or action potentials in the presynaptic membrane. 4. Guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), a hydrolysis-resistant analogue of GTP, blocked the PGP, suggesting the involvement of a G protein in the generation of K+ current. 5. Application of GABA induced depolarization or hyperpolarization in the presynaptic axon depending on the resting membrane potential. By reducing external Cl-, GABA-induced hyperpolarizations were converted to depolarizations, indicating that they are mainly mediated by Cl-. 6. In contrast to GABA, baclofen consistently induced hyperpolarization in low Cl- solution as well as in normal solution. Baclofen-induced hyperpolarization was blocked by IAP, indicating the mediation of G protein. 7. These results suggest that the presynaptic membrane of lobster neuromuscular synapse has entirely different types of amino-acid receptors from those in the postsynaptic membrane. Both the excitatory and the inhibitory axonal membrane have glutamate ("glutamateB") and GABAB receptors, which activate K+ channels via G protein.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:G protein is coupled to presynaptic glutamate and GABA receptors in lobster neuromuscular synapse. 215 71

Serotonin (5-hydroxytryptamine; 5-HT) and its analogs activate adenylate cyclase in membrane particles from neuroblastoma NCB.20 cells. Low concentrations of GTP (EC50 = 60 nM) were required for activation by serotonin. Guanosine 5'-O-(2-thiodiphosphate) inhibited serotonin-activated cyclase in these cells. The nonhydrolyzable GTP analogs guanosine 5'-O-(3-thiotriphosphate) (EC50 = 3 nM) and guanylyl-imidodiphosphate (EC50 = 100 nM) substituted for GTP in potentiating serotonin activation. Pretreatment of the cells with cholera toxin potentiated enzyme activation by serotonin, whereas pertussis toxin was found to have little effect, indicating the involvement of the alpha subunit of a stimulatory GTP-binding protein in enzyme activation. Homologous desensitization of the serotonin-stimulated adenylate cyclase was demonstrated in membranes prepared from intact cells pretreated with serotonin. Cell membrane particles that were desensitized to serotonin were still responsive to beta-adrenergic agonists and to prostaglandin E1. Evidence is presented indicating that serotonin stimulation of adenylate cyclase is mediated by receptors that are distinct from other positively coupled receptors (beta-adrenergic, histamine, and prostacyclin). Equilibrium binding analysis with [3H]serotonin, [3H]lysergic acid diethylamide, and [3H]dihydroergotamine suggested that the site density was below the level of detection of binding of these radioligands. The pharmacological characteristics of the serotonin-activated cyclases were analyzed in order to compare these serotonin receptors with the family of different receptor subtypes. Correlation analysis between the potencies of different agonists and antagonists at the cyclase in these cells and their reported relative potencies for different serotonin receptor subtypes showed no correlation with the 5-HT1A, 5HT1B, 5HT1D, 5-HT2, and 5-HT3 receptors. On the other hand, the analysis showed that the NCB.20 serotonin receptors are similar but not identical to the rat and pig brain 5-HT1C receptors and to the serotonin receptors coupled to adenylate cyclase in the trematodes Schistosoma mansoni and Fasciola hepatica. The results point to a novel serotonin receptor which has a low density in these cells.
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PMID:Serotonin receptor-mediated activation of adenylate cyclase in the neuroblastoma NCB.20: a novel 5-hydroxytryptamine receptor. 233 46

Sympathetic neurons dissociated from the superior cervical ganglion of 2-day-old rats were studied by whole-cell patch clamp and by fura-2 measurements of the cytosolic free Ca2+ concentration, [Ca2+]i. Step depolarizations in the presence of tetrodotoxin and hexamethonium triggered two Ca2+ currents that differed in the voltage dependence of activation and kinetics of inactivation. These currents resemble the L and N currents previously described in chicken sensory neurons [Nowycky, M. C., Fox, A. P. & Tsien, R. W. (1985) Nature (London) 316, 440-442]. Treatment with acetylcholine resulted in the rapid (within seconds), selective, and reversible inhibition of the rapidly inactivated, N-type current, whereas the long-lasting L-type current remained unaffected. The high sensitivity to blocker drugs (atropine, pirenzepine) indicated that this effect of acetylcholine was due to a muscarinic M1 receptor. Intracellular perfusion with nonhydrolyzable guanine nucleotide analogs or pretreatment of the neurons with pertussis toxin had profound effects on the Ca2+ current modulation. Guanosine 5'-[gamma-thio]triphosphate caused the disappearance of the N-type current (an effect akin to that of acetylcholine, but irreversible), whereas guanosine 5'-[beta-thio]diphosphate and pertussis toxin pretreatment prevented the acetylcholine-induced inhibition. In contrast, cAMP, applied intracellularly together with 3-isobutyl-1-methylxanthine, as well as activators and inhibitors of protein kinase C, were without effect. Acetylcholine caused shortening of action potentials in neurons treated with tetraethylammonium to partially block K+ channels. Moreover, when applied to neurons loaded with the fluorescent indicator fura-2, acetylcholine failed to appreciably modify [Ca2+]i at rest but caused a partial blunting of the initial [Ca2+]i peak induced by depolarization with high K+. This effect was blocked by muscarinic antagonists and pertussis toxin and was unaffected by protein kinase activators. Thus, muscarinic modulation of the N-type Ca2+ channels appears to be mediated by a pertussis toxin-sensitive guanine nucleotide-binding protein and independent of both cAMP-dependent protein kinase and protein kinase C.
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PMID:Activation of a muscarinic receptor selectively inhibits a rapidly inactivated Ca2+ current in rat sympathetic neurons. 243 97

Incubation of rabbit platelets with thrombin resulted in rapid accumulations of inositol trisphosphate (IP3) in [3H]inositol-labeled platelets, increases of [3H]arachidonic acid [( 3H]AA) release, and [3H]serotonin secretion from the platelets prelabeled with these labeled compounds. The experiments using phospholipase A2 or C inhibitor suggested that not only phospholipase C but also phospholipase A2 activity plays an important role in serotonin secretion. We then studied the regulatory mechanisms of phospholipase A2 activity. Guanosine 5'-(3-O-thio)triphosphate (GTP gamma S), guanyl-5'-(beta,gamma-iminio)triphosphate), or AlF4- caused a significant liberation of AA in digitonin-permeabilized platelets but not in intact platelets. Thrombin-stimulated AA release was not observed in permeabilized platelets, whereas thrombin acted synergistically with GTP or GTP analogs to stimulate AA release. GTP analog-stimulated AA release was inhibited by guanosine 5'-(2-O-thio)diphosphate) and was also inhibited by decreased Mg2+ concentrations. Thrombin-induced, GTP-dependent AA release, but not IP3 formation, was diminished by 100 ng/ml of pertussis toxin, associated with ADP-ribosylation of membrane 41-kDa protein(s). Thrombin-stimulated AA release from intact platelets and GTP gamma S-stimulated release from permeabilized platelets were both markedly dependent on Ca2+. However, Ca2+ addition could not enhance AA release without GTP gamma S even when Ca2+ was increased up to 10(-4) M in permeabilized platelets. The results show that thrombin-stimulated AA release from rabbit platelets is mainly mediated by phospholipase A2 activity, not by phospholipase C activity, and that Ca2+ is an important factor to the activation of phospholipase A2 but is not the sole factor to the regulation. GTP-binding protein(s) is involved in receptor-mediated activation of phospholipase A2.
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PMID:Pertussis toxin-sensitive GTP-binding proteins may regulate phospholipase A2 in response to thrombin in rabbit platelets. 250 76

Hormones have been demonstrated to activate phosphoinositide hydrolysis in plasma membranes in a manner dependent upon or potentiated by GTP. For thyrotropin-releasing hormone activation in GH3 cell membranes, stimulation persisted in membranes from pertussis toxin-treated cells. These observations indicate the presence of a membrane phospholipase C (PL C) and a novel GTP-binding protein (Gp); however, neither of these proteins has been characterized. In this paper, we report studies of GH3 membrane PL C utilizing [3H]phosphatidylinositol 4,5-bisphosphate liposome substrate. Guanosine 5'-O-(3-thiotriphosphate) (GTP[S]), but not other nucleotides, was found to stimulate PL C activity and required greater than 1 nM Ca2+. High concentrations of Ca2+ (10 microM) also activated the membrane PL C. Treatment of membranes with N-ethylmaleimide inhibited Ca2+-activated but not GTP[S]-activated PL C. Extraction of membranes with 1 M KCl solubilized the membrane PL C; however, the solubilized PL C was not GTP[S]-stimulated. N-ethylmaleimide-treated, KCl-extracted membranes were markedly deficient in GTP[S]-stimulated PL C activity; however, activity could be restored by incubation with the desalted extracted PL C. Reconstitution appeared to involve the recoupling of membrane-associated Gp with soluble 330- and 110-kDa forms of the PL C. Cytosolic PL Cs failed to substitute for the solubilized membrane PL C. These results indicate that the Gp-regulated PL C in GH3 cell membranes is an extrinsic membrane protein that can be extracted reversibly at high ionic strength. Moreover, the membrane PL C can be distinguished from cytosolic PL C isoenzymes.
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PMID:Reconstitution of a solubilized membrane but not cytosolic phospholipase C with membrane-associated Gp from GH3 cells. 251 86

Upon stimulation of human polymorphonuclear neutrophils with platelet-activating factor (PAF), arachidonic acid (AA) is released from membrane phospholipids. The mechanism for AA liberation, a key step in the synthesis of biologically active eicosanoids, was investigated. PAF was found to elicit an increase in the cytoplasmic level of free Ca2+ as monitored by fluorescent indicator fura 2. When [3H] AA-labeled neutrophils were exposed to PAF, the enhanced release of AA was observed with a concomitant decrease of radioactivity in phosphatidylinositol and phosphatidylcholine fractions. The inhibitors of phospholipase A2, mepacrine and 2-(p-amylcinnamoyl)-amino-4-chlorobenzoic acid, effectively suppressed the liberation of [3H]AA from phospholipids, indicating that liberation of AA is mainly catalyzed by the action of phospholipase A2. The extracellular Ca2+ is not required for AA release. However, intracellular Ca2+ antagonists, TMB-8 and high dose of quin 2/AM drastically reduced the liberation of AA induced by PAF, indicating that Ca2+ is an essential factor for phospholipase A2 activation. PAF raised the fluorescence of fura 2 at concentrations as low as 8 pM which reached a maximal level about 8 nM, whereas more than nM order concentrations of PAF was required for the detectable release of [3H]AA. Pretreatment of neutrophils with pertussis toxin resulted in complete abolition of AA liberation in response to PAF. However, the fura 2 response to PAF was not effectively inhibited by toxin treatment. In human neutrophil homogenate and membrane preparations, guanosine 5'-O-(thiotriphosphate) stimulated AA release and potentiated the action of PAF. Guanosine 5'-O-(thiodiphosphate) inhibited the effects of guanosine 5'-O-(thiotriphosphate). These results suggest several points: 1) PAF stimulates human polymorphonuclear neutrophils to liberate AA mainly by the action of phospholipase A2; 2) Ca2+ mobilization alone is not sufficient to stimulate AA release, although Ca2+ is the important factor for phospholipase A2 activation; and 3) a pertussis toxin-sensitive GTP-binding protein may be implicated in activation of phospholipase A2.
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PMID:Mechanism of arachidonic acid liberation in platelet-activating factor-stimulated human polymorphonuclear neutrophils. 254 86

Pretreatment with pertussis toxin inhibits angiotensin II-induced activation of polyphosphoinositide phosphodiesterase in rat renal mesangial cells [Pfeilschifter & Bauer (1986) Biochem. J. 236, 289-294]. Furthermore, activation of protein kinase C by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) and by 1-oleoyl-2-acetylglycerol (OAG) abolishes angiotensin II-induced formation of inositol trisphosphate (IP3) in mesangial cells [Pfeilschifter (1986) FEBS Lett. 203, 262-266]. Using membrane preparations of [3H]inositol-labelled mesangial cells we tried to obtain further insight as to the step at which protein kinase C might interfere with the signal transduction mechanism in mesangial cells. Angiotensin II (100 nM) stimulates IP3 formation from membrane preparations of [3H]inositol-labelled mesangial cells with a half-maximal potency of 1.1 nM. The angiotensin II-induced formation of IP3 is enhanced by GTP. This effect of angiotensin II is completely blocked by the competitive antagonist [Sar1,Ala8]angiotensin II. Guanosine 5'-[gamma-thio]triphosphate (GTP gamma S) and guanosine 5'-[beta gamma-imido]triphosphate (Gpp[NH]p), non-hydrolysable analogues of GTP, stimulate IP3 production in the absence of angiotensin II with Kd values of 0.19 microM and 2.4 microM, respectively. Angiotensin II augments the increase in IP3 formation induced by GTP gamma S. However, when mesangial cells were pretreated with TPA there was a dose-dependent inhibition of the synergistic action of angiotensin II on GTP gamma S-induced IP3 production. Comparable results are obtained with OAG, while the non-tumour-promoting phorbol ester 4 alpha-phorbol 12,13-didecanoate is without effect. These results suggest that activation of protein kinase C in mesangial cells does not impair phosphoinositide hydrolysis by stable GTP analogues but somehow seems to interfere with the stimulatory interaction of the occupied angiotensin II receptor with the transducing G-protein.
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PMID:Different effects of phorbol ester on angiotensin II- and stable GTP analogue-induced activation of polyphosphoinositide phosphodiesterase in membranes isolated from rat renal mesangial cells. 282 20

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. ADP-ribosylation with pertussis toxin (IAP) revealed the specific labelling of a single molecule of 41 kDa. No significant inhibition of VP- or AT II-stimulated IP accumulation was detected in intact cells when the whole 41 kDa molecule was endogenously ADP-ribosylated by IAP treatment. On the contrary, when glomerulosa cells were infected with cholera toxin (CT), both the VP- and AT II-stimulated IP accumulations were inhibited in a dose-dependent manner. Yet these effects were partial even at high concentrations of CT, and could not be related to the ADP-ribosylation of 'alpha s' molecules. Similarly, when the cells were infected with 1 microgram of CT/ml, the specific binding of VP and AT II decreased by 50-60%. Such results may signify that the treatment primarily affects the densities of the hormone receptors. When glomerulosa cells were incubated for 15 h in the presence of 10 nM-corticotropin (ACTH), a condition in which the intracellular concentration of cyclic AMP was increased 3-fold, the maximum IP response to 0.1 microM-VP or -AT II was decreased by 50%. When similar experiments were carried out only after a 15 min incubation period with the same concentration of ACTH, the increase in cyclic AMP was more pronounced, but no inhibition of hormone-induced IP accumulation was observed. Altogether, these results may suggest that CT exerts its action on the VP- or AT II-sensitive phospholipase C systems via a prolonged increase in intracellular cyclic AMP.
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PMID:Cholera-toxin and corticotropin modulation of inositol phosphate accumulation induced by vasopressin and angiotensin II in rat glomerulosa cells. 284 33

In Swiss 3T3 fibroblasts bradykinin stimulated inositol phosphate (InsP) formation and prostaglandin E2 (PGE2) synthesis. The EC50 values for stimulation of PGE2 synthesis and InsP formation by bradykinin were similar, 200 pM and 275 pM, respectively. Guanosine-5'-[gamma-thio]triphosphate stimulated PGE2 synthesis and InsP formation, and guanosine-5'-[beta-thio]diphosphate inhibited both PGE2 synthesis and InsP formation stimulated by bradykinin. Neither bradykinin-stimulated PGE2 synthesis nor InsP formation was sensitive to pertussis toxin. Phorbol ester, dexamethasone, and cycloheximide distinguished between bradykinin-stimulated PGE2 synthesis and InsP formation. Phorbol 12-myristate 13-acetate enhanced bradykinin-stimulated PGE2 synthesis but inhibited bradykinin-stimulated InsP formation. Pretreatment of cells with dexamethasone for 24 hr inhibited bradykinin-stimulated PGE2 synthesis but was without effect on bradykinin-stimulated InsP formation. Cycloheximide inhibited bradykinin-stimulated PGE2 synthesis but was without effect on bradykinin-stimulated InsP formation. When bradykinin was added to cells prelabeled with [3H]choline, the phospholipase A2 products lysophosphatidylcholine and glycerophosphocholine were generated. In cells pretreated with dexamethasone, lysophosphatidylcholine and glycerophosphocholine formation induced by bradykinin were inhibited. Treatment of cells with phorbol ester enhanced bradykinin-induced formation of these metabolites. The data suggest that bradykinin receptors are coupled by GTP-binding proteins to both phospholipase C and phospholipase A2 and that phospholipase A2 is the enzyme that catalyzes release of arachidonate for prostaglandin synthesis.
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PMID:Dissociation of bradykinin-induced prostaglandin formation from phosphatidylinositol turnover in Swiss 3T3 fibroblasts: evidence for G protein regulation of phospholipase A2. 288 13

Thyrotropin-releasing hormone (TRH) stimulated a rapid rise in inositol trisphosphate (IP3) formation and prolactin release from 7315c tumor cells. The potencies (half-maximal) of TRH in stimulating IP3 formation and prolactin release were 100 +/- 30 and 140 +/- 30 mM, respectively. Pretreatment of the cells with pertussis toxin (for up to 24 h) had no effect on either process. Pretreatment of the cells with cholera toxin (30 nM for 24 h) also failed to affect basal or TRH-stimulated IP3 formation. TRH was also able to stimulate IP3 formation with a half-maximal potency of 118 +/- 10 nM in a lysed cell preparation of 7315c cells; the TRH-stimulated formation of IP3 was enhanced by GTP. 5'-Guanosine gamma-thiotriphosphate (GTP gamma S) and 5'-guanylyl imidodiphosphate (Gpp(NH)p), nonhydrolyzable analogs of GTP, stimulated IP3 formation in the absence of TRH with half-maximal potencies of 162 +/- 50 and 7500 +/- 4300 nM, respectively. In contrast to the lack of effect of pertussis toxin on the TRH receptor system, treatment of 7315c cells with pertussis toxin for 3 h or longer completely abolished the ability of morphine, an opiate agonist, to inhibit either adenylate cyclase activity or prolactin release. During this 3-h treatment, pertussis toxin was estimated to induce the endogenous ADP ribosylation of more than 70% of Ni, the inhibitory GTP-binding protein. GTP gamma S and Gpp(NH)p inhibited cholera toxin-stimulated adenylate cyclase activity (presumably by acting at Ni) with half-maximal potencies of 25 +/- 9 and 240 +/- 87 nM, respectively. Finally, Gpp(NH)p was also able to inhibit the [32P]ADP ribosylation of Ni with a half-maximal potency of 300 nM. These results suggest that a novel GTP-binding protein, distinct from Ni, couples the TRH receptor to the formation of IP3.
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PMID:Coupling of the thyrotropin-releasing hormone receptor to phospholipase C by a GTP-binding protein distinct from the inhibitory or stimulatory GTP-binding protein. 301 86


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