Stimulus-Secretion Coupling: Ions
Stephen W. Carmichael, Susan L. Stoddard in The Adrenal Medulla 1986 - 1988, 2017
Inoue and Kenimer (1988) investigated muscarinic receptor-stimulated norepinephrine release in the influx of calcium into PC12 cells. They showed that the muscarinic agonist methacholine stimulates calcium influx and norepinephrine release in a dose-dependent manner. Experiments performed in a sodium-free medium or with inhibitors of voltage-dependent calcium channels suggested the involvement of a receptor-activated calcium channel that differs significantly from the voltage-dependent calcium channel involved in nicotinic receptor-stimulated release. These effects were inhibited by pertussis toxin. These experiments provide the first evidence that muscarinic stimulation evokes neurotransmitter secretion by opening a receptor-activated calcium channel that is controlled by a pertussis toxin-sensitive protein.
Alpha Adrenergic Modulation of Impulse Initiation in Normal and Ischemic Cardiac Fibers
Samuel Sideman, Rafael Beyar in Analysis and Simulation of the Cardiac System — Ischemia, 2020
To test whether this same control mechanism occurred in cardiac tissue in situ, we performed a series of experiments on adult canine Purkinje fibers.31 Some of these were incubated in pertussis toxin for 24 h to ADP ribosylate the 41-kDa regulatory protein; others were incubated in Tyrode’s solution, alone, as controls. We found that of the control fibers incubated in Tyrode’s solution, about two thirds showed a decrease in automaticity and a relatively high pertussis toxin substrate (approximately 25 fmol/mg of crude protein); the other one third showed an increase in automaticity and a lower substrate level (about 15 fmol/mg). Exposure to graded concentrations of pertussis toxin reduced the concentrations of substrate that were detectable, until at 0.5 μg/ml of toxin, no substrate at all was detectable. As the substrate concentration decreased, the proportion of fibers showing a decrease in automaticity also diminished until, at 0.5 μg/ml of toxin, all fibers showed increased automaticity.
Melanoma Growth Stimulatory Activity: Physiology, Biology, Structure/Function, and Role in Disease
Richard Horuk in Chemoattractant Ligands and Their Receptors, 2020
Once G-proteins uncouple from the receptor after the ligand binds, in some cells there is an activation of phospholipase C (PLC). Usually the β1 and β2 isoforms are activated.122–125 Interestingly, for the chemokine receptors, there is as yet very little information regarding the activation of PLC after receptor binding. IL-8 has been shown to activate phospholipase D (PLD) in neutrophils,126 while MGSA/GROα and NAP-2 do not.127 Pretreatment with pertussis toxin inhibited this activity.126 These data suggest that the effects of IL-8 on PLD activity are mediated through the IL-8 RA and not the IL-8 RB. The IL-8 stimulation of PLD activity was reduced or eliminated when cells were pretreated with the tyrosine kinase inhibitors erbstatin and herbimycin A, respectively. L’Heureux et al. concluded that while tyrosine kinase activation in response to IL-8 is necessary for stimulation of PLD activity, it is not sufficient.127 IL-8 stimulated both significant superoxide production and CD1 lb expression, whereas MGSA/GROα and NAP-2 did not, thus indicating that the signal transduction through the A and B receptors in neutrophils is apparently different, though one cannot rule out the possibility that some of the differences are derived from expression of differing numbers of these two receptors on neutrophils.
Pertussis-like syndrome often not associated with Bordetella pertussis: 5-year study in a large children’s hospital
Published in Infectious Diseases, 2020
Qin Xiong, Shiying Hao, Lei Shen, Jian Liu, Tingting Chen, Guoqin Zhang, Yu-juan Huang
The diagnosis of PLS was made for patients who met the clinical diagnostic criteria of pertussis but with indeterminate aetiology. In this study we found that the majority (96.0%) of PLS patients were infants less than 12 months. Infants are at increased risk of airway obstruction, due to unique anatomical features they have such as narrow trachea and bronchus, soft cartilage, lack of elastic tissue, poor airway support ability, poor cilia movement, and weak sputum elimination ability. Infants’ respiratory muscles are underdeveloped, and their lungs cannot expand sufficiently, leading to hypoxia and carbon dioxide storage. In addition, their poor innate immune response limits the ability of removing foreign bodies and pathogens that are invading the respiratory tract. When the pathogen is immersed in the respiratory tract, the pathogen adheres to the surface of ciliated epithelial cells of throat and bronchiole mucosa, where a variety of toxins are produced. The toxins can cause epithelial cell cilia paralysis and cell degeneration, leading to the accumulation of mucus and necrotic epithelial cells in the small bronchi. Such accumulation blocks the secretion and irritates the peripheral nerves of the respiratory tract, which induces whooping cough, rash, vomiting, and other typical symptoms of pertussis [25]. Pertussis toxin is associated with the onset of pertussis-like symptoms. It is not a necessary condition to cause pertussis-like symptoms though.
Group A streptococcal M-protein specific antibodies and T-cells drive the pathology observed in the rat autoimmune valvulitis model
Published in Autoimmunity, 2019
Suchandan Sikder, Georgina Price, Md Abdul Alim, Anil Gautam, Robert Scott Simpson, Catherine Margaret Rush, Brenda Lee Govan, Natkunam Ketheesan
Recombinant M5 protein of GAS was cloned and purified as described previously [18,34]. Priming injection of donor rats (n = 4 per group) was performed with 0.5 mg/rat GAS rM5 protein mixed with CFA s.c. in the hock region [30]. Three booster injections were given at 7-day intervals with 0.5 mg/rat GAS rM5 in IFA s.c. in the flank booster injections (Figure 1). Control donor rats were injected with PBS in CFA (priming injection) or IFA (booster injections). Bordetella pertussis toxin (Gibco, #PHZ1174, 0.3 µg/rat) was injected i.p. at day 1 and 3 after the priming injection. Adjuvant CFA, IFA and Bordetella pertussis toxin were used to enhance autoimmunity development [35]. The injection schedule described in Table 1 was followed. Donor rats were killed 35 days after priming, and serum and splenocytes were collected for transfer to syngeneic recipient rats [30]. Previous work in our own and our collaborator’s laboratories suggest that carditis can be observed in this model from 35 days post-priming injection [30,34].
Transgenic rice seeds expressing altered peptide ligands against the M3 muscarinic acetylcholine receptor suppress experimental sialadenitis-like Sjögren’s syndrome
Published in Modern Rheumatology, 2020
Hanae Kudo, Hiroto Tsuboi, Hiromitsu Asashima, Hiroyuki Takahashi, Yuko Ono, Saori Abe, Fumika Honda, Yuya Kondo, Yuhya Wakasa, Fumio Takaiwa, Makoto Takano, Minoru Matsui, Isao Matsumoto, Takayuki Sumida
The M3R−/− mice were immunized intradermally at the base of the tail with an M3R peptide mixture (N-terminal regions: N1 [MTLHSNSTTSPLFPNISSSWVHSPSEAGLP], N2 [VHSPSEAGLPLGTVSQLDSYNISQTSGNFS], N3 [NISQTSGNFSSNDTSSDPLGGHTIWQV]; and 3 extracellular loops: first [FTTYIIMNRWALGNLACDLW], second [QYFVGKRTVPPGECFIQFLSEP], third [VLVNTFCDSCIPKTYWNLGY]; each 20 µg) emulsified with Freund’s incomplete adjuvant (IFA; Difco) containing 250 mg of inactivated Mycobacterium tuberculosis (H37Ra; Difco). Pertussis toxin (500 mg; Sigma-Aldrich) was injected intraperitoneally on the day of immunization. Ten days after the immunization, each mouse received another intradermal injection of the same peptides emulsified with IFA containing H37Ra. On day 20 after the first immunization, splenocytes from the M3R−/− mice were isolated and resuspended in PBS, and 1 × 107 cells were injected intravenously into the Rag1−/− mice (Figure 2).