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)

Nitric oxide (NO) synthesized within mammalian sinoatrial cells has been shown to participate in cholinergic control of heart rate (HR). However, it is not known whether NO synthesized within neurons plays a role in HR regulation. HR dynamics were measured in 24 wild-type (WT) mice and 24 mice in which the gene for neuronal NO synthase (nNOS) was absent (nNOS-/- mice). Mean HR and HR variability were compared in subsets of these animals at baseline, after parasympathetic blockade with atropine (0.5 mg/kg i.p.), after beta-adrenergic blockade with propranolol (1 mg/kg i.p.), and after combined autonomic blockade. Other animals underwent pressor challenge with phenylephrine (3 mg/kg i.p.) after beta-adrenergic blockade to test for a baroreflex-mediated cardioinhibitory response. The latter experiments were then repeated after inactivation of inhibitory G proteins with pertussis toxin (PTX) (30 microgram/kg i.p.). At baseline, nNOS-/- mice had higher mean HR (711+/-8 vs. 650+/-8 bpm, P = 0.0004) and lower HR variance (424+/-70 vs. 1,112+/-174 bpm2, P = 0.001) compared with WT mice. In nNOS-/- mice, atropine administration led to a much smaller change in mean HR (-2+/-9 vs. 49+/-5 bpm, P = 0.0008) and in HR variance (64+/-24 vs. -903+/-295 bpm2, P = 0.02) than in WT mice. In contrast, propranolol administration and combined autonomic blockade led to similar changes in mean HR between the two groups. After beta-adrenergic blockade, phenylephrine injection elicited a fall in mean HR and rise in HR variance in WT mice that was partially attenuated after treatment with PTX. The response to pressor challenge in nNOS-/- mice before PTX administration was similar to that in WT mice. However, PTX-treated nNOS-/- mice had a dramatically attenuated response to phenylephrine. These findings suggest that the absence of nNOS activity leads to reduced baseline parasympathetic tone, but does not prevent baroreflex-mediated cardioinhibition unless inhibitory G proteins are also inactivated. Thus, neuronally derived NO and cardiac inhibitory G protein activity serve as parallel pathways to mediate autonomic slowing of heart rate in the mouse.
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PMID:Interaction between neuronal nitric oxide synthase and inhibitory G protein activity in heart rate regulation in conscious mice. 976 19

The endothelium plays an obligatory role in a number of relaxations of isolated arteries. These endothelium-dependent relaxations are due to the release by the endothelial cells of potent vasodilator substances [endothelium-derived relaxing factors (EDRF)]. The best characterized EDRF is nitric oxide (NO). Nitric oxide is formed by the metabolism of L-arginine by the constitutive NO synthase of endothelial cells. In arterial smooth muscle, the relaxations evoked by EDRF are explained best by the stimulation by NO of soluble guanylate cyclase that leads to the accumulation of cyclic GMP. The endothelial cells also release an unidentified substance that causes hyperpolarization of the cell membrane (endothelium-derived hyperpolarizing factor, EDHF). The release of EDRF from the endothelium can be mediated by both pertussis toxin-sensitive (alpha2-adrenergic activation, serotonin, thrombin, aggregating platelets) and insensitive (adenosine diphosphate, bradykinin) G-proteins. In blood vessels from animals with regenerated endothelium, and/or atherosclerosis, there is a selective loss of the pertussis-toxin sensitive mechanism of EDRF-release which favors the occurrence of vasospasm, thrombosis and cellular growth.
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PMID:Endothelial dysfunction and vascular disease. 980 82

Because several stimuli of microbial origin enhance the activity of nitric oxide synthase (NOS) in human cells of the myeloid lineage, we decided to investigate whether cellular damage induced by Aspergillus terreus mycotoxins could be associated with an increase in NOS activity. A pool of mycotoxins rather than individual toxins was tested so that the natural conditions could be mimicked. In the present study, we report that a crude extract of A. terreus induces cellular damage and increases NOS activity in K-562 cells, an erythroleukaemic cell line in which NOS is particularly active. The specificity of this association was further investigated by using NOS inhibitors and by comparing, in the same cellular model, the effects of the extract with the activity of other microbial toxins of a defined mechanism of action. Canavanine, an inhibitor of NOS, significantly reduced cell death in the presence of the extract, suggesting that cellular damage, induced by the mycotoxins of A. terreus is at least in part mediated by NOS activity. Moreover, Escherichia coli lipopolysaccharide (LPS), known to be a potent NOS inducer, increased NOS activity in our experimental model as well. In contrast, Bordetella pertussis toxin did not show any effect on NOS activity. The results of this study suggest that NOS may be involved in mycotoxicoses.
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PMID:Effect of Aspergillus terreus mycotoxins on nitric oxide synthase activity in human erythroid K-562 cells. 1019 7

1. Experiments were designed to determine whether anandamide affects cytosolic Ca2+ concentrations in endothelial cells and, if so, whether CB1 cannabinoid receptors are involved. To this effect, human umbilical vein-derived EA.hy926 endothelial cells were loaded with fura-2 to monitor changes in cytosolic Ca2+ using conventional fluorescence spectrometry methods. 2. Anandamide induced an increase in Ca2+ in endothelial cells which, in contrast to histamine, developed slowly and was transient. Anandamide caused a concentration-dependent release of Ca2+ from intracellular stores without triggering capacitative Ca2+ entry, contrary to histamine or the endoplasmic reticulum Ca2+ -ATPase inhibitor thapsigargin. 3. Anandamide pretreatment slightly reduced the mobilization of Ca2+ from intracellular stores that was evoked by histamine. The mobilization of Ca2+ from intracellular stores evoked by anandamide was impaired by 10 mM caffeine. 4. Anandamide and histamine each significantly increased NO synthase activity in EA.hy926 cells, as determined by the enhanced conversion of L-[3H]-arginine to L-[3H]-citruline. 5. The CB1 cannabinoid receptor antagonist SR141716A (1 microM) only produced a marginal reduction of the mobilization of Ca2+ produced by 5 microM anandamide. However, at 5 microM SR141716A elicited the release of Ca2+ from intracellular stores. This concentration strongly impaired the mobilization of cytosolic Ca2+ evoked by either anandamide, histamine or thapsigargin. 6. Pretreatment of the cells with either 200 microM phenylmethylsulphonyl fluoride (to inhibit the conversion of anandamide into arachidonic acid) or 400 ng ml(-1) pertussis toxin (to uncouple CB1 cannabinoid receptors from Gi/o proteins) had no significant effect on the mobilization of cytosolic Ca2+ evoked by either anandamide, or histamine. 7. Taken together the results demonstrate that anandamide mobilizes Ca2+ from a caffeine-sensitive intracellular Ca2+ store that functionally overlaps in part with the internal stores mobilized by histamine. However, a classical CB1 cannabinoid receptor-mediated and pertussis toxin-sensitive mechanism does not mediate this novel effect of anandamide in endothelial cells. 8. The mobilization of cytosolic Ca2+ in endothelial cells may account for the endothelium-dependent and NO-mediated vasodilator actions of anandamide. Due to its non-specific inhibition of Ca2+ signalling in endothelial cells, SR141716A may not be used to assess the physiological involvement of endogenous cannabinoids to endothelium-dependent control of vascular smooth muscle tone.
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PMID:Anandamide-induced mobilization of cytosolic Ca2+ in endothelial cells. 1032 91

The aim of this study was to determine the effect of ethanol on endothelial nitric oxide synthase (eNOS), the enzyme responsible for the production of the important vasoactive agent nitric oxide. The effect of ethanol (0.8-160 mM) on both basal and flow-stimulated eNOS activity was determined using cultured bovine aortic endothelial cells (EC). In "static" EC ethanol dose-dependently increased basal eNOS activity with a maximum response (approximately 2.0-fold increase) achieved at 40 mM in the absence of any effect on cell viability or nitric oxide synthase protein expression. Pertussis toxin (PTX) pretreatment significantly inhibited the ethanol-induced increase in basal eNOS activity. EC exposed to steady laminar flow exhibited a flow- and time-dependent increase in eNOS activity. Ethanol significantly enhanced the laminar flow-induced eNOS response from 0.62 +/- 0.1 to 1.06 +/- 0. 06 pmol [14C]citrulline/mg/min, a response that was inhibited by PTX. PTX-catalyzed ribosylation of Gialpha substrates, an index of G-protein functional activity, was increased in laminar flow-exposed EC compared with static controls and was further enhanced by ethanol treatment. Likewise, EC exposed to low ( approximately 0.5 dynes/cm2) and high ( approximately 12 dynes/cm2) pulsatile flow demonstrated increased eNOS activity, an effect that was associated with increased PTX-catalyzed ribosylation of Gialpha substrates. Ethanol enhanced the low flow response in a PTX-sensitive manner. These data demonstrate a stimulatory effect of ethanol on basal and flow-stimulated eNOS activity, mediated in part by a mechanism involving a PTX-sensitive G protein.
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PMID:Ethanol enhances basal and flow-stimulated nitric oxide synthase activity in vitro by activating an inhibitory guanine nucleotide binding protein. 1033 19

1. Experiments were made to investigate mechanisms by which adenosine 5'-trisphosphate (ATP) enhanced vasomotion in mesenteric lymphatic vessels isolated from young guinea-pigs. 2. ATP (10-8 - 10-3 M) caused a concentration-dependent increase of perfusion-induced vasomotion with the endothelium mediating a fundamental role at low ATP concentrations (10-8 - 10-6 M). 3. The response to 10-6 M ATP showed tachyphylaxis when applied at intervals of 10 min but not at intervals of 20 or 30 min. 4. Suramin (10-4 M) or reactive blue 2 (3x10-5 M) but not PPADS (3x10-5 M) abolished the excitatory response to 10-6 M ATP confirming an involvement of P2 purinoceptors. 5. The excitatory response to 10-6 M ATP was abolished by treatment with either pertussis toxin (100 ng ml-1), antiflammin-1 (10-9 M), indomethacin (3x10-6 M) or SQ29548 (3x10-7 M), inhibitors of specific G proteins, phospholipase A2, cyclo-oxygenase and thromboxane A2 receptors respectively. 6. ATP simultaneously induced a suramin-sensitive inhibitory response, which was normally masked by the excitatory response. ATP-induced inhibition was mediated by endothelium-derived nitric oxide (EDNO) as the response was abolished by NG-nitro-L-arginine (L-NOARG; 10-4 M), an inhibitor of nitric oxide synthase. 7. We conclude that ATP modulates lymphatic vasomotion by endothelium-dependent and endothelium-independent mechanisms. One of these is a dominant excitation caused through endothelial P2 purinoceptors which because of an involvement of a pertussis toxin sensitive G-protein may be of the P2Y receptor subtype. Their stimulation increases synthesis of phospholipase A2 and production of thromboxane A2, an arachidonic acid metabolite which acts as an endothelium-derived excitatory factor.
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PMID:Evidence that the ATP-induced increase in vasomotion of guinea-pig mesenteric lymphatics involves an endothelium-dependent release of thromboxane A2. 1045 15

The cardiac L-type calcium current (I(Ca,L)) is an important regulator of myocardial contractility. It is activated by sympathetic stimulation and inhibited by parasympathetic activity via muscarinic acetylcholine receptors. Muscarinic inhibition of I(Ca,L) occurs via activation of pertussis toxin (PTX)-sensitive heterotrimeric G-proteins. Although recent studies have shown that expression of G(oalpha) is important for this effect in adult mouse ventricular cells, two other PTX-sensitive G-proteins (G(i2) and G(i3)) are also expressed in cardiocytes and are activated. Their role in the regulation of I(Ca,L) has not been examined. In addition, it is not known whether nodal/atrial cardiac cells use the same G-proteins. We show that gene inactivation of each of the three PTX-sensitive Galpha-proteins (alpha(i2), alpha(i3), and alpha(o)) affects muscarinic inhibition of cardiac I(Ca,L) in embryonic stem (ES) cell-derived cardiocytes. Inactivation of either alpha(i2) or alpha(i3) markedly slows the time course of muscarinic inhibition of I(Ca,L), and in cells where both alpha(i2) and alpha(i3) are inactivated the effects are not additive. We also establish an essential role for alpha(o)in this atrial/nodal-like cardiocyte system and show that alpha(o)acts proximal to NO generation. NO generation plays a critical role in I(Ca,L) regulation since the nitric oxide synthase (NOS) antagonist, l -NMMA, blocked the inhibition of I(Ca,L) in WT and in alpha(i2)/alpha(i3)-null cells. In WT cells, the NO generating agent SIN-1 inhibited I(Ca,L) and the addition of carbachol resulted in faster inhibition, suggesting that pathways in addition to NO are also activated. This study shows that alpha(i2) and alpha(i3) play a critical role in the normal inhibition of cardiocyte I(Ca,L). Thus, all muscarinic receptor activated G-proteins (G(i2), G(i3) and G(o)) are necessary for normal inhibition and act through both NO and non-NO signaling pathways.
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PMID:Galpha(i2), Galpha(i3)and Galpha(o) are all required for normal muscarinic inhibition of the cardiac calcium channels in nodal/atrial-like cultured cardiocytes. 1047 59

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

Adenosine is known to play an important role in the regulation of coronary blood flow during metabolic stress. However, there is sparse information on the mechanism of adenosine-induced dilation at the microcirculatory levels. In the present study, we examined the role of endothelial nitric oxide (NO), G proteins, cyclic nucleotides, and potassium channels in coronary arteriolar dilation to adenosine. Pig subepicardial coronary arterioles (50 to 100 microm in diameter) were isolated, cannulated, and pressurized to 60 cm H(2)O without flow for in vitro study. The arterioles developed basal tone and dilated dose dependently to adenosine. Disruption of endothelium, blocking of endothelial ATP-sensitive potassium (K(ATP)) channels by glibenclamide, and inhibition of NO synthase by N(G)-nitro-L-arginine methyl ester and of soluble guanylyl cyclase by 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one produced identical attenuation of vasodilation to adenosine. Combined administration of these inhibitors did not further attenuate the vasodilatory response. Production of NO from coronary arterioles was significantly increased by adenosine. Pertussis toxin, but not cholera toxin, significantly inhibited vasodilation to adenosine, and this inhibitory effect was only evident in vessels with an intact endothelium. Tetraethylammonium, glibenclamide, and a high concentration of extraluminal KCl abolished vasodilation of denuded vessels to adenosine; however, inhibition of calcium-activated potassium channels by iberiotoxin had no effect on this dilation. Rp-8-Br-cAMPS, a cAMP antagonist, inhibited vasodilation to cAMP analog 8-Br-cAMP but failed to block adenosine-induced dilation. Furthermore, vasodilations to 8-Br-cAMP and sodium nitroprusside were not inhibited by glibenclamide, indicating that cAMP- and cGMP-induced dilations are not mediated by the activation of K(ATP) channels. These results suggest that adenosine activates both endothelial and smooth muscle pathways to exert its vasodilatory function. On one hand, adenosine opens endothelial K(ATP) channels through activation of pertussis toxin-sensitive G proteins. This signaling leads to the production and release of NO, which subsequently activates smooth muscle soluble guanylyl cyclase for vasodilation. On the other hand, adenosine activates smooth muscle K(ATP) channels and leads to vasodilation through hyperpolarization. It appears that the latter vasodilatory process is independent of G proteins and of cAMP/cGMP pathways.
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PMID:cAMP-independent dilation of coronary arterioles to adenosine : role of nitric oxide, G proteins, and K(ATP) channels. 1050 88

Cerebellar granule cells (CGCs) express the CB(1) subtype of cannabinoid receptor. CB(1) receptor agonists Win 55212-2, CP55940 and HU210 inhibit KCl-induced activation of nitric oxide synthase (NOS) in CGCs. Win 55212-2 has no effect on either basal NOS activity or on activation by N-methyl-D-aspartate and its effect is abolished by pre-treatment of the cells with pertussis toxin. The CB(1) receptor antagonist/inverse agonist SR141716A both reverses the effects of Win 55212-2 and produces an increase in NOS activity that is additive with KCl. These results support the hypothesis that activation of the CB(1) receptor in CGCs results in a decreased influx of calcium in response to membrane depolarization, resulting in a decreased activation of neuronal NOS.
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PMID:Effects of CB(1) cannabinoid receptor activation on cerebellar granule cell nitric oxide synthase activity. 1051 35


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