Exogenous Substance

2016 ◽  
Author(s):  
Monica Nordberg ◽  
John H. Duffus ◽  
Douglas M. Templeton
Keyword(s):  
Exogenous Substance

Thyrotropin-releasing hormone: an inhibitory regulatory peptide of feline lower esophageal sphincter

1993 ◽  
Vol 264 (3) ◽  
pp. G522-G527 ◽  
Author(s):  
H. P. Parkman ◽  
J. C. Reynolds ◽  
C. P. Ogorek ◽  
M. S. Kreider
Keyword(s):  
Gastrointestinal Tract ◽  
Substance P ◽  
Lower Esophageal Sphincter ◽  
Muscle Layer ◽  
Left Gastric Artery ◽  
Thyrotropin Releasing Hormone ◽  
Relative Distribution ◽  
Releasing Hormone ◽  
Exogenous Substance ◽  
Esophageal Sphincter

The functional role of thyrotropin-releasing hormone (TRH) at the lower esophageal sphincter (LES) was examined in the cat. The specific aims of this study were to determine: 1) the relative distribution of TRH throughout the feline gastrointestinal tract and 2) the effect of TRH on LES basal pressures and its response to exogenously induced contractions. TRH concentrations were determined by radioimmunoassay in tissue extracts from 12 sites. The mean concentration of TRH at the manometrically determined LES was 240 +/- 85 pg/g wet wt tissue, and the maximal concentration was just distal to the LES (659 +/- 189 pg/g wet wt). TRH concentration was higher in the mucosa than the underlying muscle layer of the fundus, antrum, duodenum, and ileum. In physiological studies, TRH given selectively via the left gastric artery had no effect on basal LES or esophageal pressures. TRH (2.8 x 10(-8) mol/kg) decreased the LES response to the D50 of substance P by 47.2% (34.8 +/- 3.1 to 18.4 +/- 2.9 mmHg, P < 0.01). In the presence of tetrodotoxin, TRH gave a similar inhibition of substance P-induced contractions (53.5%). TRH also decreased bombesin-induced contractions by 47.5% (29.6 +/- 6.0 to 15.8 +/- 3.9 mmHg, P < 0.025). TRH, however, had no effect on bethanechol-induced contractions. We conclude that 1) TRH is present throughout the gastrointestinal tract, with highest concentrations in the region distal to the LES; 2) TRH has no effect on basal LES tone; and 3) TRH inhibits the LES response to endogenously released and exogenous substance P but not the LES response to bethanechol.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta 2-adrenoceptor agonists inhibit NANC neural bronchoconstrictor responses in vitro

1993 ◽  
Vol 74 (3) ◽  
pp. 1195-1199 ◽  
Author(s):  
G. M. Verleden ◽  
M. G. Belvisi ◽  
K. F. Rabe ◽  
M. Miura ◽  
P. J. Barnes
Keyword(s):  
Substance P ◽  
Guinea Pig ◽  
Electrical Field Stimulation ◽  
Sensory Nerves ◽  
Inhibitory Effects ◽  
Exogenous Substance ◽  
Dependent Inhibition ◽  
Adrenoceptor Agonists ◽  
Beta 2

Nonadrenergic noncholinergic (NANC) contractile responses in guinea pig bronchi are due to the release of tachykinins from airway sensory nerves. The purpose of this study was to determine whether beta 2-receptor agonists modulate NANC contractions in guinea pig bronchi in vitro. Bronchial rings were suspended in organ baths for isometric measurement of tension, and comparable contractions were induced by electrical field stimulation (EFS; 40 V, 0.5 ms, 8 Hz for 20 s) or by exogenous substance P (3 microM). Aformoterol and salbutamol produced concentration-dependent inhibition of the NANC contraction, with aformoterol being ninefold more potent than salbutamol; approximate 50% inhibitory concentrations for aformoterol and salbutamol were 1.03 nM (n = 6) and 9.3 nM (n = 6), respectively. Aformoterol also inhibited the contraction induced by exogenous substance P but to a far lesser extent than its inhibition of EFS-induced responses. The inhibitory effects of formoterol (10 nM) on responses to EFS at 8 Hz were significantly prevented by propranolol (1 microM) and ICI 118551 (a beta 2-antagonist, 0.1 microM) but not by atenolol (a beta 1-antagonist, 1 microM) or phentolamine (10 microM). These experiments demonstrate that beta 2-agonists may modulate the release of tachykinins from airway sensory nerves by prejunctional receptors.

Substance P-inducing massive postmortem bronchoconstriction in guinea pig lungs

1987 ◽  
Vol 62 (2) ◽  
pp. 746-751 ◽  
Author(s):  
Y. L. Lai ◽  
A. F. Cornett
Keyword(s):  
Substance P ◽  
Guinea Pig ◽  
Sensory Nerve ◽  
Transpulmonary Pressure ◽  
Blocking Agent ◽  
Base Line ◽  
Time Period ◽  
Exogenous Substance ◽  
Inflation Volume

To further examine the role that substance P plays in initiating the observed massive postmortem bronchoconstriction in guinea pig lungs and to explore the role of neural reflex in this airway spasm, six groups of animals were employed: control (n = 6), morphine (n = 6), substance P (n = 5), chronic capsaicin pretreatment + substance P (n = 5), tetrodotoxin (TTX) + acute capsaicin (n = 4), and chlorisondamine + acute capsaicin (n = 5). Pressure-volume curves were performed prior to and following the initiation of artificial pulmonary perfusion with 1% bovine serum albumin and 5% dextran in Tyrode's solution. A decrease in inflation volume (the lung volume between transpulmonary pressure of 0 and 30 cmH2O during inflation) was used as an index of bronchoconstriction. In control animals, inflation volume decreased to 20–30% of the base-line value at 15–30 min of perfusion, indicating massive bronchial constriction during this time period. Morphine (an agent inhibiting substance P release) significantly attenuated the spasm, whereas the presence of substance P in the perfusate markedly enhanced the constriction. Depletion of endogenous substance P by chronic capsaicin pretreatment did not affect exogenous substance P-induced spasm. Acute capsaicin-induced bronchoconstriction was significantly attenuated by TTX but was not affected by the ganglionic blocking agent, chlorisondamine. These data suggest that substance P initiates the massive postmortem bronchoconstriction in guinea pig lungs and that substance P is released by local stimulation of sensory nerve endings via axonal reflex.

The binding of endogenous and exogenous substance-P in human plasma

1990 ◽  
Vol 39 (7) ◽  
pp. 1161-1166 ◽  
Author(s):  
Niamh Corbally ◽  
David Powell ◽  
Keith F. Tipton
Keyword(s):  
Substance P ◽  
Human Plasma ◽  
Exogenous Substance

scholarly journals Neurokinin-1 receptor activation is sufficient to restore the hypercapnic ventilatory response in the Substance P-deficient naked mole-rat

2020 ◽  
Vol 318 (4) ◽  
pp. R712-R721 ◽  
Author(s):  
Maxwell S. Clayson ◽  
Maiah E. M. Devereaux ◽  
Matthew E. Pamenter
Keyword(s):  
Substance P ◽  
Network Architecture ◽  
Ventilatory Response ◽  
Receptor Activation ◽  
Whole Body ◽  
Hypercapnic Ventilatory Response ◽  
Exogenous Substance ◽  
Mole Rat ◽  
Freely Behaving ◽  
Neurokinin 1

Naked mole-rats (NMRs) live in large colonies within densely populated underground burrows. Their collective respiration generates significant metabolic carbon dioxide (CO2) that diffuses slowly out of the burrow network, creating a hypercapnic environment. Currently, the physiological mechanisms that underlie the ability of NMRs to tolerate environmental hypercapnia are largely unknown. To address this, we used whole-body plethysmography and respirometry to elucidate the hypercapnic ventilatory and metabolic responses of awake, freely behaving NMRs to 0%–10% CO2. We found that NMRs have a blunted hypercapnic ventilatory response (HCVR): ventilation increased only in 10% CO2. Conversely, metabolism was unaffected by hypercapnia. NMRs are insensitive to cutaneous acid-based pain caused by modified substance P (SP)-mediated peripheral neurotransmission, and SP is also an important neuromodulator of ventilation. Therefore, we re-evaluated physiological responses to hypercapnia in NMRs after an intraperitoneal injection of exogenous substance P (2 mg/kg) or a long-lived isoform of substance P {[pGlu5-MePhe8-MeGly9]SP(5-11), DiMe-C7; 40–400 μg/kg}. We found that both drugs restored hypercapnia sensitivity and unmasked an HCVR in animals breathing 2%–10% CO2. Taken together, our findings indicate that NMRs are remarkably tolerant of hypercapnic environments and have a blunted HCVR; however, the signaling network architecture required for a “normal” HCVR is retained but endogenously inactive. This muting of chemosensitivity likely suits the ecophysiology of this species, which presumably experiences hypercapnia regularly in their underground niche.

scholarly journals Possible Migration and Histopathological Analysis of Injections of Polymethylmethacrylate in Wistar Rats

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Rodrigo d'Eça Neves ◽  
Marcello Alberton Herdt ◽  
Felipe Barbieri Wohlgemuth ◽  
Jorge Bins Ely ◽  
Zulmar Antonio Accioli de Vasconcellos ◽  
...  
Keyword(s):  
Experimental Work ◽  
Wistar Rats ◽  
Subcutaneous Tissue ◽  
Histopathological Analysis ◽  
Tissue Samples ◽  
Intramuscular Injections ◽  
Exogenous Substance ◽  
Tissue Cells ◽  
The Right

Objective. To evaluate the possible migration of polymethylmethacrylate after injections in various corporal compartments of Wistar rats. Methods. The experimental work consisted in the injection of PMMA in corporal compartments for later histopathological analysis of the locations of implants and of distant filtering organs. The dose applied in each implant was of 0.2 mL. The animals were divided into groups according to the location of the implant realized: group GB had intradermic injections in the glabella. Group SD had subdermal injections in dorsal subcutaneous tissue cells. Group IP had intraperitoneal injections in the abdomen. Group PD had intramuscular injections in the right rear leg. The rats were sacrificed 30 days after realization of the implants and tissue samples from the lung, liver, spleen, and kidney, and locations of implantation were removed for histopathological analysis. Results. Characteristic microspheres that were compatible with the presence of PMMA in any of the histological slides analyzed were not observed. One animal had an amorphous exogenous substance, with a histiocytic reaction. Twelve of the 16 lungs analyzed had locations of intraalveolar hemorrhaging. Two animals had nonspecific spleen alterations. Conclusion. The histopathological analysis of this study found no PMMA microspheres in any of the tissues analyzed.

Sign in / Sign up

Export Citation Format

Share Document