Vagal and mediator mechanisms underlying the tachypnea caused by pulmonary air embolism in dogs

2000 ◽  
Vol 88 (4) ◽  
pp. 1247-1253 ◽  
Author(s):  
H. F. Chen ◽  
Y. R. Kou
Keyword(s):  
Hydroxyl Radical ◽  
Air Embolism ◽  
Radical Scavenger ◽  
C Fibers ◽  
Hydroxyl Radical Scavenger ◽  
C Fiber ◽  
Cervical Vagotomy ◽  
The Right ◽  
Spontaneously Breathing ◽  
Saline Vehicle

We investigated the vagal and mediator mechanisms underlying the tachypnea caused by pulmonary air embolism (PAE) in anesthetized and spontaneously breathing dogs. PAE was induced by infusion of air into the right atrium (0.2 ml ⋅ kg−1 ⋅ min−1for 10 min). The first PAE induction caused an increase in respiratory frequency accompanied by a decrease in tidal volume in each of the 30 animals studied. Subsequently, animals were evenly divided into five groups, and a second PAE induction was repeated after various experimental interventions. The tachypneic response to PAE was not significantly altered by pretreatment with a saline vehicle but was largely attenuated by either perivagal capsaicin treatment (a technique that selectively blocks the conduction of unmyelinated C fibers), pretreatment with ibuprofen (a cyclooxygenase inhibitor), or pretreatment with dimethylthiourea (a hydroxyl radical scavenger). Ultimately, the tachypneic response was nearly abolished by a bilateral cervical vagotomy. These results suggest that 1) lung vagal unmyelinated C-fiber afferents play a predominant role in evoking the reflex tachypneic response to PAE and 2) both cyclooxygenase products and hydroxyl radical are important in eliciting this vagally mediated response.

scholarly journals Stimulation of vagal pulmonary C fibers by inhaled wood smoke in rats

1998 ◽  
Vol 84 (1) ◽  
pp. 30-36 ◽  
Author(s):  
C. J. Lai ◽  
Y. R. Kou
Keyword(s):  
Hydroxyl Radical ◽  
Combined Treatment ◽  
Wood Smoke ◽  
Radical Scavenger ◽  
C Fibers ◽  
Hydroxyl Radical Scavenger ◽  
C Fiber ◽  
Delayed Phase ◽  
Stimulation Of ◽  
Sustained Increase

Lai, C. J., and Y. R. Kou. Stimulation of vagal pulmonary C fibers by inhaled wood smoke in rats. J. Appl. Physiol. 84(1): 30–36, 1998.—This study investigated the stimulation of vagal pulmonary C fibers (PCs) by wood smoke. We recorded impulses from PCs in 58 anesthetized, open-chest, and artificially ventilated rats and delivered 6 ml of wood smoke into the lungs. Within 1 or 2 s after the smoke delivery, an intense and nonphasic burst of discharge [Δ = +7.4 ± 0.7 (SE) impulses/s, n = 68] was evoked in 60 of the 68 PCs studied and lasted for 4–8 s. This immediate stimulation was usually followed by a delayed and more sustained increase in C-fiber activity (Δ = +2.0 ± 0.4 impulses/s). The overall stimulation was not influenced by removal of smoke particulates ( n = 15) or by pretreatment with vehicle ( n = 8) for dimethylthiourea (DMTU; a hydroxyl radical scavenger) or indomethacin (Indo; a cyclooxygenase inhibitor). The immediate-phase stimulation was not affected by pretreatment with Indo ( n= 8) but was largely attenuated by pretreatment with DMTU ( n = 12) or by a combined treatment with DMTU and Indo (DMTU+Indo; n = 8). Conversely, the delayed-phase stimulation was partially suppressed either by DMTU or by Indo but was totally abolished by DMTU+Indo. These results suggest that 1) the stimulation of PCs is linked to the gas phase of wood smoke and 2) hydroxyl radical, but not cyclooxygenase products, is involved in the immediate-phase stimulation, whereas both metabolites are responsible for evoking the delayed-phase stimulation.

scholarly journals Mechanisms of stimulation of vagal pulmonary C fibers by pulmonary air embolism in dogs

1997 ◽  
Vol 82 (3) ◽  
pp. 765-771 ◽  
Author(s):  
H. F. Chen ◽  
B. P. Lee ◽  
Y. R. Kou
Keyword(s):  
Hydroxyl Radical ◽  
Right Atrium ◽  
Air Embolism ◽  
Lung Mechanics ◽  
Cyclooxygenase Inhibitor ◽  
Functional Importance ◽  
C Fibers ◽  
The Right ◽  
Saline Vehicle ◽  
Stimulation Of

Chen, H. F., B. P. Lee, and Y. R. Kou. Mechanisms of stimulation of vagal pulmonary C fibers by pulmonary air embolism in dogs. J. Appl. Physiol. 82(3): 765–771, 1997.—We investigated the involvement of the cyclooxygenase metabolites and hydroxyl radical (⋅ OH) in the stimulation of vagal pulmonary C fibers (PCs) by pulmonary air embolism (PAE). Impulses were recorded from PCs in 51 anesthetized, open-chest, and artificially ventilated dogs. Fifty of 59 PCs were stimulated by infusion of air into the right atrium (0.2 ml ⋅ kg−1 ⋅ min−1for 10 min). As a group ( n = 59), PC activity increased from a baseline of 0.4 ± 0.1 to a peak of 1.7 ± 0.2 impulses/s during the period from 1 min before to 2 min after the termination of PAE induction. In PCs initially stimulated by PAE induction, PAE was repeated after the intervening treatment (iv) with saline ( n = 9), ibuprofen (a cyclooxygenase inhibitor; n = 11), or dimethylthiourea (a ⋅ OH scavenger; n = 12). The responses of PCs to PAE were not altered by saline vehicle but were abolished by ibuprofen and significantly attenuated by dimethylthiourea. Although hyperinflation of the lungs reversed the PAE-induced bronchomotor responses, it did not reverse the stimulation of PCs ( n= 8). These results suggest that 1) cyclooxygenase products are necessary for the stimulation of PCs by PAE, whereas changes in lung mechanics are not, and 2) the functional importance of cyclooxygenase products may be mediated in part through the formation of ⋅ OH.

Protective and defensive airway reflexes evoked by nasal exposure to wood smoke in anesthetized rats

2000 ◽  
Vol 88 (3) ◽  
pp. 863-870 ◽  
Author(s):  
C.-Y. Ho ◽  
Y. R. Kou
Keyword(s):  
Hydroxyl Radical ◽  
The Other ◽  
Wood Smoke ◽  
Radical Scavenger ◽  
Sprague Dawley ◽  
C Fibers ◽  
Sprague Dawley Rats ◽  
Nasal Application ◽  
Airway Responses ◽  
Saline Vehicle

We investigated the airway responses evoked by nasal wood smoke in anesthetized Sprague-Dawley rats. Wood smoke (5 ml, 1.4 ml/s) was delivered into an isolated nasal cavity while animals breathed spontaneously. In study 1, nasal wood smoke triggered either an apneic response ( n = 26) or a sniff-like response ( n = 16) within 1 s after smoke exposure in 42 normal rats. Both airway responses were abolished by trigeminal nerve denervation and by nasal application of a local anesthetic or a hydroxyl radical scavenger, but they were not significantly affected by removal of smoke particulates or nasal application of a saline vehicle. In study 2, nasal wood smoke only triggered a mild apneic response in two rats neonatally treated with capsaicin and had no effect on breathing in the other six; the treatment is known to chronically ablate C fibers and some Aδ fibers. In contrast, nasal wood smoke evoked an apneic response in six rats neonatally treated with the vehicle of capsaicin and elicited a sniff-like response in the other two. These results suggest that the apneic and sniff-like responses evoked by nasal wood smoke result from the stimulation of trigeminal nasal C-fiber and Aδ-fiber afferents by the gas-phase smoke and that hydroxyl radical is the triggering chemical factor.

The involvement of hydroxyl radical and cyclooxygenase metabolites in the activation of lung vagal sensory receptors by circulatory endotoxin in rats

2005 ◽  
Vol 98 (2) ◽  
pp. 620-628 ◽  
Author(s):  
Ching Jung Lai ◽  
Ting Ruan ◽  
Yu Ru Kou
Keyword(s):  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Lung Compliance ◽  
Radical Scavenger ◽  
C Fibers ◽  
C Fiber ◽  
Underlying Mechanisms ◽  
Dynamic Lung Compliance ◽  
Fiber Stimulation ◽  
Stimulation Of

Circulatory endotoxin can stimulate vagal pulmonary C fibers and rapidly adapting receptors (RARs) in rats, but the underlying mechanisms are not clear. We investigated the involvement of hydroxyl radicals and cyclooxygenase metabolites in the stimulation of C fibers and RARs by circulatory endotoxin (50 mg/kg) in 112 anesthetized, paralyzed, and artificially ventilated rats. In rats pretreated with the vehicle, endotoxin stimulated C fibers and RARs and caused a slight increase in total lung resistance (Rl) and a decrease in dynamic lung compliance. In rats pretreated with dimethylthiourea (a hydroxyl radical scavenger) alone, indomethacin (a cyclooxygenase inhibitor) alone, or a combination of the two, C-fiber and RAR responses [C fiber: change (Δ) = −62, −79, and −85%; RAR: Δ = −80, −84, and −84%, respectively] were reduced, and the Rl response was prevented. The suppressive effects of a combination of dimethylthiourea and indomethacin on the C-fiber and RAR responses were not superior to indomethacin alone. In rats pretreated with isoproterenol (a bronchodilator), the C-fiber response was not significantly affected (Δ = −26%), the RAR response was reduced (Δ = −88%), and the Rl response was prevented. None of these pretreatments affected the dynamic lung compliance response. These results suggest that 1) both hydroxyl radicals and cyclooxygenase metabolites are involved in the endotoxin-induced stimulation of C fibers and RARs, and 2) the involvement of these two metabolites in the C-fiber stimulation may be due to their chemical effects, whereas that in the RAR stimulation may be due to their bronchoconstrictive effects.

Evidence suggesting a role for hydroxyl radical in glycerol-induced acute renal failure

1988 ◽  
Vol 255 (3) ◽  
pp. F438-F443 ◽  
Author(s):  
S. V. Shah ◽  
P. D. Walker
Keyword(s):  
Renal Failure ◽  
Acute Renal Failure ◽  
Hydroxyl Radical ◽  
Tissue Injury ◽  
Iron Chelator ◽  
Radical Scavenger ◽  
Reactive Oxygen Metabolites ◽  
Protective Effects ◽  
Hydroxyl Radical Scavenger ◽  
Hydroxyl Radical Scavengers

Reactive oxygen metabolites, in particular hydroxyl radical, have been shown to be important mediators of tissue injury in several models of acute renal failure. The aim of the present study was to examine the role of hydroxyl radical in glycerol-induced acute renal failure, a model for myoglobinuric renal injury. Rats injected with glycerol alone (8 mg/kg im following dehydration for 24 h) developed significant renal failure compared with dehydrated controls. Rats treated with glycerol and a hydroxyl radical scavenger, dimethylthiourea (DMTU), had significantly lower blood urea nitrogen (BUN) and creatinine. In contrast, urea, which is chemically similar to DMTU but is not a hydroxyl radical scavenger, provided no protection. In addition, DMTU prevented the glycerol-induced rise in renal cortical malondialdehyde content (a measure of lipid peroxidation that serves as a marker of free radical-mediated tissue injury). A second hydroxyl radical scavenger, sodium benzoate, had a similar protective effect on renal function (as measured by both BUN and creatinine). Because the generation of hydroxyl radical in biological systems requires the presence of a trace metal such as iron, we also examined the effect of the iron chelator, deferoxamine on glycerol-induced renal failure. Deferoxamine was also protective. The interventional agents were also associated with a marked reduction in histological evidence of renal damage. The protective effects of two hydroxyl radical scavengers as well as an iron chelator implicate a role for hydroxyl radical in glycerol-induced acute renal failure.

scholarly journals A NOVEL HYDROXYL RADICAL SCAVENGER, NICARAVEN, ATTENUATES ISCHEMIA REPERFUSION INJURY OF THE LIVER

1998 ◽  
Vol 65 (Supplement) ◽  
pp. 148
Author(s):  
R. Yokota ◽  
T. Shimamura ◽  
T. Suzuki ◽  
M. Fukai ◽  
M. Taniguchi ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Radical Scavenger ◽  
Hydroxyl Radical Scavenger

Synthesis of New Carnosine Derivatives ofβ-Cyclodextrin and Their Hydroxyl Radical Scavenger Ability

2002 ◽  
Vol 85 (6) ◽  
pp. 1633-1643 ◽  
Author(s):  
Diego La Mendola ◽  
Salvatore Sortino ◽  
Graziella Vecchio ◽  
Enrico Rizzarelli
Keyword(s):  
Hydroxyl Radical ◽  
Radical Scavenger ◽  
Hydroxyl Radical Scavenger

Endogenous BK stimulates ischemically sensitive abdominal visceral C fiber afferents through kinin B2 receptors

1994 ◽  
Vol 267 (6) ◽  
pp. H2398-H2406 ◽  
Author(s):  
H. L. Pan ◽  
G. L. Stahl ◽  
S. V. Rendig ◽  
O. A. Carretero ◽  
J. C. Longhurst
Keyword(s):  
Receptor Antagonist ◽  
Impulse Activity ◽  
Discharge Rate ◽  
Visceral Afferents ◽  
C Fibers ◽  
C Fiber ◽  
Hoe 140 ◽  
B2 Receptors ◽  
The Right ◽  
Stimulation Of

Abdominal ischemia and reperfusion reflexly activate the cardiovascular system. In the present study, we evaluated the role of endogenously produced bradykinin (BK) in the stimulation of ischemically sensitive visceral afferents. Single-unit activity of abdominal visceral C fiber afferents was recorded from the right thoracic sympathetic chain of anesthetized cats during 5 min of abdominal ischemia. Abdominal ischemia increased the portal venous plasma BK level from 49 +/- 10 to 188 +/- 66 pg/ml (P < 0.05). Injection of BK (1 microgram/kg ia) into the descending aorta significantly increased impulse activity (0.88 +/- 0.16 impulses/s) of 10 C fibers, whereas a kinin B1-receptor agonist, des-Arg9-BK (1 microgram/kg), did not alter the discharge rate. Inhibition of kininase II activity with captopril (4 mg/kg i.v.) potentiated impulse activity of 14 ischemically sensitive C fibers (0.44 +/- 0.09 vs. precaptopril, 0.33 +/- 0.08 impulses/s; P < 0.05). In addition, a kinin B2-receptor antagonist (NPC-17731; 40 micrograms/kg i.v.) attenuated activity of afferents during ischemia (0.39 +/- 0.08 vs. pre-NPC-17731, 0.72 +/- 0.13 impulses/s; P < 0.05) and eliminated the response of 10 C fibers to BK. Another kinin B2-receptor antagonist, Hoe-140 (30 micrograms/kg iv), had similar inhibitory effects on six other ischemically sensitive C fibers. In 15 separate cats treated with aspirin (50 mg/kg i.v.), Hoe-140 (30 micrograms/kg i.v.) attenuated impulse activity of only 3 of 16 ischemically sensitive C fibers. These data suggest that BK produced during abdominal ischemia contributes to the stimulation of ischemically sensitive visceral C fiber afferents through kinin B2 receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

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