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 secretion of alphaMSH from the intermediate lobe of the frog pituitary is regulated by multiple factors, including classical neurotransmitters and neuropeptides. In particular, acetylcholine (ACh), acting via muscarinic receptors, stimulates alphaMSH release from frog neurointermediate lobes (NILs) in vitro. The aim of the present study was to characterize the type of receptor and the transduction pathways involved in the mechanism of action of ACh on frog melanotrope cells. The nonselective muscarinic receptor agonists muscarine and carbachol both stimulated alphaMSH release from perifused frog NILs, whereas the M1-selective muscarinic agonist McN-A-343 was virtually devoid of effect. Both the M1>M3 antagonist pirenzepine and the M3>M1 antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide inhibited muscarine-induced alphaMSH release. Administration of a brief pulse of muscarine in the vicinity of cultured melanotrope cells provoked a 4-fold increase in the cytosolic calcium concentration ([Ca2+]i). Suppression of Ca2+ in the culture medium or addition of 3 mM Ni2+ abrogated the stimulatory effect of muscarine on [Ca2+]i and alphaMSH release. In contrast, omega-conotoxin GVIA and nifedipine did not significantly reduce the stimulatory effect of muscarine on [Ca2+]i and alphaMSH secretion. Exposure of NILs to muscarine provoked an increase in inositol phosphate formation, and this effect was dependent on extracellular Ca2+. The inhibitor of polyphosphoinositide turnover neomycin significantly attenuated the muscarine-evoked alphaMSH release. Similarly, pretreatment of frog NILs with phorbol ester markedly reduced the secretory response to muscarine. In contrast, the stimulatory effect of muscarine on alphaMSH release was not affected by the phospholipase A2 inhibitor dimethyl eicosadienoic acid or by the tyrosine kinase inhibitors lavendustin A, genistein, and tyrphostin 25. Muscarine at a high concentration (10(-4) M) only produced a 40% increase in cAMP formation. Preincubation of frog NILs with pertussis toxin did not significantly affect the muscarine-induced stimulation of alphaMSH release. These results indicate that frog melanotrope cells express a muscarinic receptor subtype pharmacologically related to the mammalian M3 receptor. Activation of this receptor causes calcium influx through Ni2+-sensitive Ca2+ channels and subsequent activation of the phopholipase C/protein kinase C transduction pathway.
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PMID:Pharmacological and functional characterization of muscarinic receptors in the frog pars intermedia. 968 4

In the present study, we describe the role of inositol trisphosphate in the signalling pathway that leads to the elevation of cytosolic-free Ca2+ in rat neutrophils stimulated with magnolol, a compound isolated from the cortex of Magnolia officinalis. Magnolol increased [Ca2+]i, by stimulating Ca2+ release from internal stores and Ca2+ influx across the plasma membrane, in a concentration-dependent manner. Ni2+ and [6-[[(17beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H -pyrrole-2,5-dione (U73122), but not pertussis toxin, inhibited the magnolol-induced Ca2+ influx. Measurement of cellular levels of inositol trisphosphate showed a clear increase upon exposure to magnolol. U73122 but not ryanodine suppressed the Ca2+ release from internal stores caused by magnolol. Pretreatment of cells with formyl-Met-Leu-Phe (fMLP) or cyclopiazonic acid greatly reduced the [Ca2+]i changes caused by the subsequent addition of magnolol. Collectively, these findings suggest that a pertussis toxin-insensitive inositol trisphosphate signalling pathway is involved in the magnolol-induced [Ca2+]i elevation in rat neutrophils.
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PMID:Magnolol induces cytosolic-free Ca2+ elevation in rat neutrophils primarily via inositol trisphosphate signalling pathway. 971 70

An efficient one-step affinity purification of bovine brain G protein betagamma subunits (betagamma's) is described. The betagamma's, in a detergent extract of brain membranes, are first dissociated from the alpha subunits (alpha's), reassociated with decahistidine-tagged alphail produced in bacteria, and then adsorbed onto Ni2+-nitrilotriacetic acid-agarose via the histidine tag. This mild adsorption retained the high activity of the ligand alpha's, in contrast to the commonly used chemical crosslinking methods. A wash step with a buffer containing chaotropic ions (SCN-) completely removed contaminating proteins that were refractory to washes with high concentrations of detergents, after which the highly purified betagamma's were eluted with a buffer containing Al3+, Mg2+, and F- ions. The obtained betagamma's were found to be fully functional, as assessed by their ability to support pertussis toxin-catalyzed ADP-ribosylation of alphail. Since the combination of the mild adsorption via the histidine tag and the wash with chaotropic ions can be easily applied to purifying betagamma's from various animal tissues, this new chromatographic method is expected to facilitate the purification of other membrane proteins that bind to Galpha and/or Galphabetagamma.
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PMID:One-step affinity purification of the G protein betagamma subunits from bovine brain using a histidine-tagged G protein alpha subunit. 1004 77

The mechanism of arginine vasopressin (AVP)-induced arachidonic acid (AA) release was examined in the cardiac myoblast cell line, H9c2. Stimulation of cells with AVP induced dose-dependent AA release, and this effect was completely inhibited by the V1 receptor antagonist, d(CH)5[Tyr(Me)2]AVP. AVP also produced dose-dependent stimulation of inositol phosphate formation; this was not affected by pertussis toxin, indicating the presence of the V1 receptor/Gq protein/PLCbeta pathway in H9c2 cells. The concentration-response curves for these two effects of AVP overlapped. AVP induced a rapid increase in [Ca2+]i, followed by a sustained increase. The Ca2+ ionophore, A23187 or ionomycin, mimicked the effect of AVP, whereas the protein kinase C (PKC) activator, TPA, only induced a slight increase in AA release. Both the AVP- or A23187-stimulated AA release and the AVP-induced sustained [Ca2+]i increase were completely blocked in the absence of external Ca2+. The receptor-operated Ca2+ channel blocker, SKF 96365, and the inorganic Ca2+ channel blockers, Ca2+ and Ni2+, also inhibited the AVP-induced AA release. Western blots demonstrated expression of PKCalpha, betaI, epsilon, delta, and zeta in H9c2 cells; PKC inhibitors (staurosporine or Ro 31-8220) or down-regulation of PKCalpha, betaI, epsilon, and delta by long-term (24 h) TPA treatment caused a partial blockade of the AVP-induced response, whereas the A23187-induced AA release was unaffected by down-regulation of these isoforms. AVP-induced, but not A23187-induced, AA release was partially blocked by the p42 MAPK cascade inhibitor, PD 98059. AVP and TPA, but not A23187, induced an increase in activity and tyrosine phosphorylation of p42 MAPK, together with a molecular weight shift, consistent with phosphorylation, of cytosolic PLA2. AVP- or TPA-induced activation and tyrosine phosphorylation of p42 MAPK were completely blocked by down-regulation of PKCalpha, betaI, epsilon, and delta, but still occurred, together with the cytosolic PLA2 mobility shift, in the absence of external Ca2+. These results show that AVP-induced AA release in H9c2 cells is secondary to activation of the V1 receptor/Gq protein/PLCP pathway, leading to an influx of extracellular Ca2+ and activation of PKCalpha, betaI, epsilon, and delta. The influx of extracellular Ca2- and DAG act, respectively, through PKC-/MAPK-independent or PKC-dependent MAPK pathways to mediate AA release.
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PMID:Signal transduction of arginine vasopressin-induced arachidonic acid release in H9c2 cardiac myoblasts: role of Ca2+ and the protein kinase C-dependent activation of p42 mitogen-activated protein kinase. 1009 98

1. Experiments were designed to differentiate the mechanisms and subtype of kinin receptors mediating the changes in intracellular Ca2+ concentration ([Ca2+]i) induced by bradykinin (BK) in canine cultured tracheal epithelial cells (TECs). 2. BK and Lys-BK caused an initial transient peak of [Ca2+]i in a concentration-dependent manner, with half-maximal stimulation (pEC50) obtained at 7.70 and 7.23, respectively. 3. Kinin B2 antagonists Hoe 140 (10 nM) and [D-Arg0, Hyp3, Thi5,8, D-Phe7]-BK (1 microM) had high affinity in antagonizing BK-induced Ca2+ response with pKB values of 8.90 and 6.99, respectively. 4. Pretreatment of TECs with pertussis toxin (100 ng ml(-1)) or cholera toxin (10 microg ml(-1)) for 24 h did not affect the BK-induced IP accumulation and [Ca2+]i changes in TECs. 5. Removal of Ca2+ by the addition of EGTA or application of Ca2+-channel blockers, verapamil, diltiazem, and Ni2+, inhibited the BK-induced IP accumulation and Ca2+ mobilization, indicating that Ca2+ influx was required for the BK-induced responses. 6. Addition of thapsigargin (TG), which is known to deplete intracellular Ca2+ stores, transiently increased [Ca2+]i in Ca2+-free buffer and subsequently induced Ca2+ influx when Ca2+ was re-added to this buffer. Pretreatment of TECs with TG completely abolished BK-induced initial transient [Ca2+]i, but had slight effect on BK-induced Ca2+ influx. 7. Pretreatment of TECs with SKF96365 and U73122 inhibited the BK-induced Ca2+ influx and Ca2+ release, consistent with the inhibition of receptor-gated Ca2+-channels and phospholipase C in TECs, respectively. 8. These results demonstrate that BK directly stimulates kinin B2 receptors and subsequently phospholipase C-mediated IP accumulation and Ca2+ mobilization via a pertussis toxin-insensitive G protein in canine TECs. These results also suggest that BK-induced Ca2+ influx into the cells is not due to depletion of these Ca2+ stores, as prior depletion of these pools by TG has no effect on the BK-induced Ca2+ influx that is dependent on extracellular Ca2+ in TECs.
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PMID:Bradykinin-induced phosphoinositide hydrolysis and Ca2+ mobilization in canine cultured tracheal epithelial cells. 1021 27

1. In isolated rat mesenteric artery with endothelium, NaF caused slowly developing hyperpolarization. The hyperpolarizing effect was unchanged in the presence of N(G)-nitro-L-arginine (L-NOARG) and indomethacin, but was markedly reduced by high K+. In Ca2+ -free medium or in the presence of Ni2+, NaF failed to produce hyperpolarization. 2. NaF-induced hyperpolarization was substantially unaffected by deferoxamine, an Al3+ chelator, okadaic acid and calyculin A, phosphatase inhibitors, and preincubation with pertussis toxin, suggesting that neither the action of fluoroaluminates as a G protein activator nor inhibition of phosphatase activity contributes to the hyperpolarizing effect. 3. The selective inhibitors of the Ca2+ -pump ATPase of endoplasmic reticulum, thapsigargin and cyclopiazonic acid, elicited hyperpolarization, whose properties were very similar to those of NaF. When intracellular Ca2+ stores had been depleted with these inhibitors, NaF no longer generated hyperpolarization. 4. In Ca2+ -free medium, NaF (or thapsigargin) caused a transient increase in the cytosolic Ca2+ concentration ([Ca2+]i) in cultured porcine aortic endothelial cells, and subsequent application of thapsigargin (or NaF) failed to increase [Ca2+]i. 5. In arterial rings precontracted with phenylephrine, NaF produced endothelium-dependent relaxation followed by sustained contraction even in the presence of L-NOARG and indomethacin. The relaxant response was abolished by high K+ or cyclopiazonic acid. 6. These results indicate that NaF causes endothelium-dependent hyperpolarization, thereby leading to smooth muscle relaxation of rat mesenteric artery. This action appears to be mediated by the promotion of Ca2+ influx into endothelial cells that can be triggered by the emptying of intracellular Ca2+ stores, as proposed for those of thapsigargin and cyclopiazonic acid.
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PMID:Relationship between NaF- and thapsigargin-induced endothelium-dependent hyperpolarization in rat mesenteric artery. 1032 88

The effect of 5-hydroxytryptamine (5-HT) on phospholipase C (PLC)-mediated phosphoinositide (PI) hydrolysis and intracellular Ca2+ ([Ca2+]i) changes was investigated in canine cultured aorta smooth muscle cells (ASMCs). 5-HT-stimulated inositol phosphate (IP) accumulation was time and concentration dependent with a half-maximal response (pEC50) and a maximal response at 6.4 and 10 microM, n = 6, respectively. Stimulation of ASMCs by 5-HT produced an initial transient peak followed by a sustained, concentration-dependent elevation in [Ca+]i. The half-maximal response (pEC50) values of 5-HT for the peak and sustained plateau were 7.1 and 6.9, respectively. Ketanserin and mianserin (1 and 3 nM), 5-HT2A antagonists, were equipotent and had high affinity in antagonising the 5-HT-induced IP accumulation and [Ca2+]i change with pK(B) values of 8.6-9.1 and 8.6-9.4, respectively. In contrast, the concentration-effect curves of 5-HT-induced IP and [Ca2+]i responses were not shifted until the concentrations of NAN-190 and metoctopramide (5-HT1A and 5-HT3 receptor antagonists, respectively) were increased to as high as 1 microM with pK(B) values of 5.7-6.3 and 6.1-6.6, respectively, indicating that the 5-HT receptor-mediated responses had low affinity for these antagonists. Pre-treatment of ASMCs with pertussis toxin (100 ng/mL, 24 h) caused a significant inhibition of 5-HT-induced IP accumulation and [Ca2+]i change in ASMCs. Depletion of external Ca2+ or removal of Ca2+ by addition of EGTA led to a significant attenuation of IP accumulation and [Ca2+]i change induced by 5-HT. Influx of external Ca2+ was required for the 5-HT-induced responses, because Ca2+-channel blockers--verapamil, nifedipine and Ni2+--partly inhibited the 5-HT-induced IP accumulation and Ca2+ mobilisation. The sustained elevation of [Ca2+]i response to 5-HT was dependent on the presence of external Ca2+. Removal of external Ca2+ by addition of 5 mM EGTA during the sustained phase caused a rapid decline in [Ca2+]i to lower than the resting level. The sustained elevation of [Ca2+]i could then be evoked by addition of 1.8 mM Ca2+ in the continued presence of 5-HT. These results demonstrate that 5-HT directly stimulates PLC-mediated PI hydrolysis and Ca2+ mobilisation, at least in part, through a pertussis toxin-sensitive G protein in canine ASMCs. 5-HT2A receptors may be predominantly mediating IP accumulation, and subsequently IP-induced Ca2+ mobilisation may function as the transducing mechanism for 5-HT-stimulated contraction of aorta smooth muscle.
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PMID:5-Hydroxytryptamine-induced phosphoinositide hydrolysis and Ca2+ mobilisation in canine cultured aorta smooth muscle cells. 1037 10

In a previous publication we provided evidence of a novel neuronal pathway for the control of GnRH secretion by bradykinin. The action of bradykinin appeared to be exerted through the bradykinin B2 receptor. In this study we demonstrated that the bradykinin B2 receptor is densely localized in the arcuate nucleus, median eminence, organum vasculosum of the lamina terminalis, and preoptic area, regions known to be critical for the control of GnRH secretion. To determine the mechanism of action of bradykinin in stimulating GnRH release, we used immortalized GnRH (GT1-7) cells in vitro. Bradykinin stimulation of GnRH secretion from GT1-7 cells appears to involve activation of the phospholipase C signaling pathway and mobilization of extracellular and intracellular calcium stores. Evidence to support this contention was derived from the observations that incubation of the phospholipase C inhibitor, U-73122 with bradykinin, blocked the ability of bradykinin to stimulate release from GT1-7 cells. This effect was specific, as a nitric oxide synthase inhibitor and a cyclooxygenase inhibitor were found to have no effect on bradykinin-induced GnRH secretion, suggesting that nitric oxide and PGs do not mediate bradykinin effects. Pertussis toxin also had no effect on bradykinin action. This suggests that the bradykinin B2 receptor may be coupled to a pertussis toxin-insensitive G protein in GT1-7 cells. With respect to calcium involvement in bradykinin action, fura-2 calcium indicator studies revealed that bradykinin can rapidly increase intracellular Ca2+ levels in GT1-7 cells. A role for intracellular Ca2+ in bradykinin action was further suggested by the finding that an intracellular calcium chelator, 1,2-bis(O-aminophenoxy)]ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester, significantly attenuated the effects of bradykinin on GnRH release. The elevation of intracellular calcium by bradykinin appears to be due to mobilization of calcium from the endoplasmic reticulum, as incubation of the Ca2+-adenosine triphosphatase inhibitor thapsigarin, which depletes endoplasmic reticulum Ca2+ stores, significantly attenuated bradykinin action on GnRH release. Extracellular calcium may also be involved in bradykinin action, as the L-type Ca2+ channel blockers verapamil and nifedipine had no effect on bradykinin-induced GnRH release, whereas the nonselective Ca2+ channel blocker, nickel chloride, attenuated bradykinin-induced GnRH release. Taken as a whole, these studies demonstrate that the bradykinin B2 receptor is densely localized in key hypothalamic nuclei responsible for regulation of GnRH release, and that the mechanism of bradykinin stimulation of GnRH secretion involves activation of the phospholipase C signaling pathway, with a critical role implicated for calcium in bradykinin action in GT1-7 cells.
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PMID:Bradykinin receptor localization and cell signaling pathways used by bradykinin in the regulation of gonadotropin-releasing hormone secretion. 1049 24

The pharmacological properties of bradykinin receptors were characterized in rat cultured vascular smooth muscle cells (VSMCs) using [3H]-bradykinin as a ligand. Analysis of binding isotherms gave an apparent equilibrium dissociation constant (K(D)) of 1.2 +/- 0.2 nM and a maximum receptor density (Bmax) of 47.3 +/- 4.4 fmol/mg protein. The specific binding of [3H]-bradykinin to VSMCs was inhibited by the B2 receptor-selective agonists (bradykinin and kallidin) and antagonists ([D-Arg0, Hyp3, Thi5, D-Tic7, Oic8]-bradykinin (Hoe 140) and [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin) with an order of potency as kallidin = bradykinin = Hoe 140 > [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin, but not by a B1 receptor-selective agonist (des-Arg9-bradykinin) and antagonist ([Leu8, des-Arg9]-bradykinin). Stimulation of VSMCs by bradykinin produced a concentration-dependent inositol phosphate (IP) accumulation, and initial transient peak of [Ca2+]i with half-maximal responses (pEC50) were 7.53 and 7.69, respectively. B2 receptor-selective antagonists (Hoe 140 and [D-Arg0, Hyp3, Thi(5,8), D-Phe7]-bradykinin) significantly antagonized the bradykinin-induced responses with pK(B) values of 8.3-8.7 and 7.2-7.9, respectively. Pretreatment of VSMCs with pertussis toxin (100 ng/ml, 24 h) did not alter the bradykinin-induced inositol phosphate accumulation and [Ca2+]i changes in VSMCs. Removal of external Ca2+ led to a significant attenuation of responses induced by bradykinin. Influx of external Ca2+ was required for the bradykinin-induced responses, since Ca2+-channel blockers, nifedipine, verapamil, and Ni2+, partially inhibited the bradykinin-induced IP accumulation and Ca2+ mobilization. These results demonstrate that bradykinin stimulates phosphoinositide hydrolysis and Ca2+ mobilization via a pertussis toxin-insensitive G-protein in rat VSMCs. Bradykinin B2 receptors may be predominantly mediating IP accumulation and subsequently induction of Ca2+ mobilization may function as the transducing mechanism for bradykinin-stimulated contraction of vascular smooth muscle.
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PMID:Pharmacological and functional characterization of bradykinin receptors in rat cultured vascular smooth muscle cells. 1065 93

The modulation of a transient T-type calcium current by the five muscarinic receptor subtypes, stably expressed in NIH 3T3 cells, was studied with the whole-cell patch-clamp technique. Voltage-step depolarizations applied to the NIH 3T3 cells revealed a low-voltage-activated (LVA) T-type calcium current that was inhibited by Ni2+ and unaffected by omega-conotoxin GVIA. In cells transfected with the m3 and m5 muscarinic receptors, application of acetylcholine (ACh) resulted in a pertussis-toxin-insensitive increase in peak T-type calcium current amplitude. The m3-induced atropine-sensitive increase in current amplitude was accompanied by a shift in the voltage dependence of activation to more hyperpolarized potentials. The increase in peak T-type calcium current amplitude and the shift in voltage dependence was mimicked by incubation with 500 microM 8-bromo-cAMP. Conversely, T-type calcium current amplitudes were reduced by incubation with 10 microM RpcAMPS, an inhibitor of cAMP-dependent protein kinase (PKA). Preincubation with 500 microM 8-bromo-cAMP or with 10 microM RpcAMPS abolished the increase in T-type calcium current amplitude previously noted on stimulation of the m3 muscarinic receptor by ACh. Application of ACh to NIH 3T3 cells stably transformed with the m1 muscarinic receptor resulted in no discernable change in T-type calcium current amplitude. However, on pre-incubation of the cells with calphostin C, an inhibitor of protein kinase C (PKC), application of ACh to the cells now resulted in a robust increase in T-type calcium current amplitude. Application of 500 nM PDBu, an activator of PKC, reduced the T-type calcium current amplitude. No significant changes in T-type calcium currents were observed on application of ACh to cells stably transfected with the m2 or m4 muscarinic receptors. However, after pre-incubation with forskolin, the m2 muscarinic receptor induced a decrease in T-type calcium current amplitude. Stimulation of the ml, m3 and m5 muscarinic receptors in the NIH 3T3 cell resulted in dose-dependent increases in the concentration of intracellular cAMP in comparison to control as determined by cAMP immunoassay. Conversely, stimulation of the m2 and m4 muscarinic receptors by carbachol resulted in a dose-dependent reduction in intracellular concentrations of cAMP, as compared with control basal levels. It is concluded that the m3 and m5 muscarinic receptors enhance T-type calcium channel activity. At least in the case of the m3 muscarinic receptor, the increased T-type channel activity appeared to be mediated via increased cAMP levels and subsequent activation of PKA. The lack of effect of the ml muscarinic receptor on the T-type calcium channel was probably due to the opposing actions of concomitant activation of both PKC and PKA. The physiological significance of these findings is discussed.
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PMID:Modulation of low-threshold T-type calcium channels by the five muscarinic receptor subtypes in NIH 3T3 cells. 1095 32


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