The role of calcium channels in substance P-induced contractile response in the rat iris

Abstract Background Abdominal pain is a common complaint in patients with chronic gastrointestinal disorders. Accumulating evidence suggests that gut microbiota is an important determinant of gut function, including visceral sensitivity. Germ-free (GF) mice have been shown to display visceral hypersensitivity, which normalizes after colonization. Sex also appears to play a key role in visceral sensitivity, as women report more abdominal pain than men. Thus, both gut bacteria and sex are important in the regulation of gut nociception, but the underlying mechanisms remain poorly understood. Aims To investigate the role of gut microbiota and sex in abdominal pain. Methods We used primary cultures of sensory neurons from dorsal root ganglia (DRG) of female and male conventionally raised (SPF) or germ-free (GF) mice (7–18 weeks old). To study the visceral afferent activity in vitro, calcium mobilization in DRG sensory neurons was measured by inverted fluorescence microscope using a fluorescent calcium probe Fluo-4 (1mM). Two parameters were considered i) the percentage of responding neurons ii) the intensity of the neuronal response. First, DRG sensory neurons were stimulated by a TRPV1 agonist capsaicin (12.5nM, 125nM and 1.25µM) or by a mixture of G-protein coupled receptors agonist (GPCR: bradykinin, histamine and serotonin; 1µM, 10µM and 100µM). We next measured the neuronal production of substance P and calcitonin gene-related peptide (CGRP), two neuropeptides associated with nociception, in response to capsaicin (1.25µM) or GPCR agonists (100µM) by ELISA and EIA, respectively. Results The percentage of neurons responding to capsaicin and GPCR agonists was similar in male and female SPF and GF mice. However, the intensity of the neuronal response was higher in SPF male compared to SPF female in response to capsaicin (125nM: p=0.0336; 1.25µM: p=0.033) but not to GPCR agonists. Neuronal activation was similar in GF and SPF mice of both sexes after administration of capsaicin or GPCR agonists. Furthermore, substance P and CGRP production by sensory neurons induced by capsaicin or GPCR agonists was similar in SPF and GF mice, regardless of sex. However, while the response to capsaicin was similar, the GPCR agonists-induced production of substance P was higher in SPF male mice compared to SPF females (p=0.003). The GPCR agonists-induced production of CGRP was similar in SPF male and female mice. Conclusions Our data suggest that at the level of DRG neurons, the absence of gut microbiota does not predispose to visceral hypersensitivity. The intensity of DRG neuronal responses to capsaicin and the GPCR agonists-induced production of substance P are higher in male compared to female mice, in contrast to previously published studies in various models of acute and chronic pain. Further studies are thus needed to investigate the role of sex in visceral sensitivity. Funding Agencies CIHR

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Role of the C Domain of IGFs in Synergistic Promotion, with a Substance P–Derived Peptide, of Rabbit Corneal Epithelial Wound Healing

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.03-0626 ◽

2004 ◽

Vol 45 (4) ◽

pp. 1125 ◽

Cited By ~ 33

Author(s):

Naoyuki Yamada ◽

Ryoji Yanai ◽

Masatsugu Nakamura ◽

Makoto Inui ◽

Teruo Nishida

Keyword(s):

Wound Healing ◽

Substance P ◽

Corneal Epithelial ◽

Epithelial Wound Healing

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Neurochemical activity of noradrenergic neurons and pituitary-adrenal response after naloxone-induced withdrawal: the role of calcium channels

Naunyn-Schmiedeberg s Archives of Pharmacology ◽

10.1007/pl00004975 ◽

1997 ◽

Vol 355 (4) ◽

pp. 501-506 ◽

Cited By ~ 26

Author(s):

M. L. Vargas ◽

M. G. Martínez-Piñero ◽

M. V. Milanés

Keyword(s):

Calcium Channels ◽

Noradrenergic Neurons ◽

Adrenal Response

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Role of substance P in allergic nasal symptoms in rats

European Journal of Pharmacology ◽

10.1016/j.ejphar.2005.12.020 ◽

2006 ◽

Vol 532 (1-2) ◽

pp. 155-161 ◽

Cited By ~ 7

Author(s):

Md. Ashequr Rahman ◽

Toshio Inoue ◽

Chiaki Kamei

Keyword(s):

Substance P ◽

Nasal Symptoms

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Paradoxical effect of salbutamol in a model of acute organophosphates intoxication in guinea pigs: role of substance P release

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00253.2005 ◽

2007 ◽

Vol 292 (4) ◽

pp. L915-L923 ◽

Cited By ~ 10

Author(s):

Jaime Chávez ◽

Patricia Segura ◽

Mario H. Vargas ◽

José Luis Arreola ◽

Edgar Flores-Soto ◽

...

Keyword(s):

Substance P ◽

Guinea Pigs ◽

Smooth Muscle Contraction ◽

In Vivo Experiments ◽

Intracellular Ca ◽

Neurokinin 1 ◽

Substance P Release

Organophosphates induce bronchoobstruction in guinea pigs, and salbutamol only transiently reverses this effect, suggesting that it triggers additional obstructive mechanisms. To further explore this phenomenon, in vivo (barometric plethysmography) and in vitro (organ baths, including ACh and substance P concentration measurement by HPLC and immunoassay, respectively; intracellular Ca2+ measurement in single myocytes) experiments were performed. In in vivo experiments, parathion caused a progressive bronchoobstruction until a plateau was reached. Administration of salbutamol during this plateau decreased bronchoobstruction up to 22% in the first 5 min, but thereafter airway obstruction rose again as to reach the same intensity as before salbutamol. Aminophylline caused a sustained decrement (71%) of the parathion-induced bronchoobstruction. In in vitro studies, paraoxon produced a sustained contraction of tracheal rings, which was fully blocked by atropine but not by TTX, ω-conotoxin (CTX), or epithelium removal. During the paraoxon-induced contraction, salbutamol caused a temporary relaxation of ∼50%, followed by a partial recontraction. This paradoxical recontraction was avoided by the M2- or neurokinin-1 (NK1)-receptor antagonists (methoctramine or AF-DX 116, and L-732138, respectively), accompanied by a long-lasting relaxation. Forskolin caused full relaxation of the paraoxon response. Substance P and, to a lesser extent, ACh released from tracheal rings during 60-min incubation with paraoxon or physostigmine, respectively, were significantly increased when salbutamol was administered in the second half of this period. In myocytes, paraoxon did not produce any change in the intracellular Ca2+ basal levels. Our results suggested that: 1) organophosphates caused smooth muscle contraction by accumulation of ACh released through a TTX- and CTX-resistant mechanism; 2) during such contraction, salbutamol relaxation is functionally antagonized by the stimulation of M2 receptors; and 3) after this transient salbutamol-induced relaxation, a paradoxical contraction ensues due to the subsequent release of substance P.

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The role of substance P in the pathogenesis of experimental allergic neuritis

Regulatory Peptides ◽

10.1016/0167-0115(93)90050-i ◽

1993 ◽

Vol 46 (1-2) ◽

pp. 251-253

Author(s):

Shujian Wu ◽

Juan Chen ◽

Chengtao Xu

Keyword(s):

Substance P ◽

Experimental Allergic Neuritis ◽

Experimental Allergic ◽

Allergic Neuritis

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Halothane Inhibition of Recombinant Cardiac L-type Ca2+ Channels Expressed in HEK-293 Cells

Anesthesiology ◽

10.1097/00000542-200512000-00009 ◽

2005 ◽

Vol 103 (6) ◽

pp. 1156-1166 ◽

Cited By ~ 7

Author(s):

Kevin J. Gingrich ◽

Son Tran ◽

Igor M. Nikonorov ◽

Thomas J. Blanck

Keyword(s):

Charge Transfer ◽

Calcium Channels ◽

Dependent Manner ◽

Current Time ◽

Hek 293 ◽

Hek 293 Cells ◽

293 Cells ◽

Dependent Inactivation ◽

Voltage Dependent

Background Volatile anesthetics depress cardiac contractility, which involves inhibition of cardiac L-type calcium channels. To explore the role of voltage-dependent inactivation, the authors analyzed halothane effects on recombinant cardiac L-type calcium channels (alpha1Cbeta2a and alpha1Cbeta2aalpha2/delta1), which differ by the alpha2/delta1 subunit and consequently voltage-dependent inactivation. Methods HEK-293 cells were transiently cotransfected with complementary DNAs encoding alpha1C tagged with green fluorescent protein and beta2a, with and without alpha2/delta1. Halothane effects on macroscopic barium currents were recorded using patch clamp methodology from cells expressing alpha1Cbeta2a and alpha1Cbeta2aalpha2/delta1 as identified by fluorescence microscopy. Results Halothane inhibited peak current (I(peak)) and enhanced apparent inactivation (reported by end pulse current amplitude of 300-ms depolarizations [I300]) in a concentration-dependent manner in both channel types. alpha2/delta1 coexpression shifted relations leftward as reported by the 50% inhibitory concentration of I(peak) and I300/I(peak)for alpha1Cbeta2a (1.8 and 14.5 mm, respectively) and alpha1Cbeta2aalpha2/delta1 (0.74 and 1.36 mm, respectively). Halothane reduced transmembrane charge transfer primarily through I(peak) depression and not by enhancement of macroscopic inactivation for both channels. Conclusions The results indicate that phenotypic features arising from alpha2/delta1 coexpression play a key role in halothane inhibition of cardiac L-type calcium channels. These features included marked effects on I(peak) inhibition, which is the principal determinant of charge transfer reductions. I(peak) depression arises primarily from transitions to nonactivatable states at resting membrane potentials. The findings point to the importance of halothane interactions with states present at resting membrane potential and discount the role of inactivation apparent in current time courses in determining transmembrane charge transfer.

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