Inhibitory Effects of Imidazolines on Histamine Liberation from Human Leukocytes and on Tracheal Smooth Muscle Tone

The effects of Ascaris suum antigen on tracheal circulation and tracheal smooth muscle tone were compared in two groups of sheep: the first group was 1 yr old (14 sheep) and the second 5 yr old (8 sheep). Cranial tracheal arteries of anesthetized and paralyzed sheep were perfused at constant flow with monitoring of perfusion pressure. Tracheal smooth muscle tone was assessed by measuring changes in the external diameter of the cranial trachea. Close-arterial injection of antigen (1–20 micrograms) in young sheep produced dose-dependent vasodilation (6.1–15.5% fall in perfusion pressure) and smooth muscle contraction (0.06–0.28 mm reduction in tracheal diam). In old sheep, antigen (1–20 micrograms) produced vasoconstriction (4.1–16.8%) but no smooth muscle response. The smooth muscle contraction in young sheep was blocked by mepyramine (2 mg/kg iv) suggesting mediation by release of histamine. The vasodilation in young sheep and the vasoconstriction in old sheep were reduced by indomethacin (5 mg/kg iv), and the residual response was further reduced by FPL 55712 (2 mg/kg iv), suggesting mediation by both cyclooxygenase products and leukotrienes. Thus antigen given in the tracheal vasculature releases a mixture of inflammatory mediators. This mixture of mediators or their actions on the tracheal vasculature and smooth muscle may depend on the age of the sheep.

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Response of tracheal smooth muscle tone to lower brain stem hypoxia in dogs

Journal of the Autonomic Nervous System ◽

10.1016/0165-1838(96)00045-8 ◽

1996 ◽

Vol 60 (3) ◽

pp. 136-140 ◽

Cited By ~ 1

Author(s):

Iunis Suzuki ◽

Tetsuri Kondo ◽

Yutaka Hirokawa ◽

Yasuyo Ohta ◽

Hideho Arita

Keyword(s):

Smooth Muscle ◽

Brain Stem ◽

Muscle Tone ◽

Tracheal Smooth Muscle ◽

Smooth Muscle Tone ◽

Lower Brain Stem

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EVIDENCE THAT TRACHEAL SMOOTH MUSCLE TONE IN GUINEA-PIG IS UNAFFECTED BY OVERFLOW OF NORADRENALINE RELEASED BY PERIVASCULAR NERVE FIBRES

Clinical and Experimental Pharmacology and Physiology ◽

10.1111/j.1440-1681.1987.tb01865.x ◽

1987 ◽

Vol 14 (10) ◽

pp. 745-754

Author(s):

R. V. Smith ◽

D. G. Satchell

Keyword(s):

Smooth Muscle ◽

Guinea Pig ◽

Muscle Tone ◽

Tracheal Smooth Muscle ◽

Nerve Fibres ◽

Smooth Muscle Tone

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The Direct Effects of Heparin and Protamine on Canine Tracheal Smooth Muscle Tone

Anesthesia & Analgesia ◽

10.1213/00000539-199906000-00009 ◽

1999 ◽

Vol 88 (6) ◽

pp. 1232-1238 ◽

Cited By ~ 3

Author(s):

Michiaki Yamakage ◽

Takashi Matsuzaki ◽

Naoki Tsujiguchi ◽

Tomohisa Mori ◽

Akiyoshi Namiki

Keyword(s):

Smooth Muscle ◽

Muscle Tone ◽

Tracheal Smooth Muscle ◽

Direct Effects ◽

Smooth Muscle Tone

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Tracheal smooth muscle responses to upper airway pressure in conscious dogs

Journal of Applied Physiology ◽

10.1152/jappl.1990.68.4.1555 ◽

1990 ◽

Vol 68 (4) ◽

pp. 1555-1561 ◽

Cited By ~ 5

Author(s):

L. Plowman ◽

P. H. Edwards ◽

D. C. Lauff ◽

M. Berthon-Jones ◽

C. E. Sullivan

Keyword(s):

Smooth Muscle ◽

Airway Smooth Muscle ◽

Airway Pressure ◽

Breathing Pattern ◽

Muscle Tone ◽

Upper Airway ◽

Tracheal Smooth Muscle ◽

Smooth Muscle Tone ◽

Pressure Stimulus ◽

Tracheal Stoma

We studied the influence of changes in pressure applied to the isolated upper airway of four conscious dogs on tracheal smooth muscle tone and breathing pattern. The dogs were prepared with a permanent side-hole tracheal stoma and were trained to sleep with a snout mask hermetically sealed in place while breathing through a cuffed endotracheal tube inserted distally into the tracheal stoma. Changes in tracheal smooth muscle tone were continuously monitored by measuring the pressure in the water-filled cuff that distended the tracheal airway while pressure changes were introduced in the upper airway independently of breathing. Increases or decreases of upper airway pressure (+/- 10 cmH2O) had little effect on tracheal airway smooth muscle tone. In contrast, an oscillating pressure wave at 30 Hz and +/- 3 cmH2O amplitude (or -3 to -7 cmH2O amplitude) caused a marked increase in tracheal airway smooth muscle tone. An elevated tracheal airway tone could be maintained over many minutes when the oscillating pressure stimulus was pulsed so that there was a cycle of 0.5 s on, 0.5 s off. This stimulus did not change the functional residual capacity but resulted in coughing, swallowing, or sighing in 54% of the tests. In the remaining tests, the pressure stimulus produced a rapid, shallow, and erratic breathing pattern. The tracheal airway constrictor response (but not the ventilatory response) was completely abolished by intravenous atropine. We suggest that upper airway vibration is a potentially powerful mechanism of reflex airway smooth muscle constriction.

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Tracheal constrictor drive above the apneic threshold in anesthetized dogs

Journal of Applied Physiology ◽

10.1152/jappl.2000.89.6.2258 ◽

2000 ◽

Vol 89 (6) ◽

pp. 2258-2262

Author(s):

J. A. Silverman ◽

L. Z. Sommer ◽

A. Robicsek ◽

J. Dickstein ◽

A. Greenberg ◽

...

Keyword(s):

Smooth Muscle ◽

Tidal Volume ◽

Muscle Tone ◽

Respiratory Frequency ◽

Tracheal Smooth Muscle ◽

Smooth Muscle Tone ◽

Anesthetized Dogs ◽

Receptor Input ◽

Small Increments ◽

F 14

We have previously shown that raising arterial Pco 2 (PaCO2 ) by small increments in dogs ventilated below the apneic threshold (AT) results in almost complete tracheal constriction before the return of phrenic activity (Dickstein JA, Greenberg A, Kruger J, Robicsek A, Silverman J, Sommer L, Sommer D, Volgyesi G, Iscoe S, and Fisher JA. J Appl Physiol 81: 1844–1849, 1996). We hypothesized that, if increasing chemical drive above the AT mediates increasing constrictor drive to tracheal smooth muscle, then pulmonary slowly adapting receptor input should elicit more tracheal dilation below the AT than above. In six methohexital sodium-anesthetized, paralyzed, and ventilated dogs, we measured changes in tracheal diameter in response to step increases in tidal volume (Vt) or respiratory frequency (f) below and above the AT at constant PaCO2 (∼40 and 67 Torr, respectively). Increases in Vt(400–1,200 ml) caused significantly more ( P = 0.005) tracheal dilation below than above AT (7.0 ± 2.2 vs. 2.8 ± 1.0 mm, respectively). In contrast, increases in f (14–22 breaths/min) caused similar ( P = 0.93) tracheal dilations below and above (1.0 ± 1.3 and 1.0 ± 0.8 mm, respectively) AT. The greater effectiveness of dilator stimuli below compared with above the AT is consistent with the hypothesis that drive to tracheal smooth muscle increases even after attainment of maximal constriction. Our results emphasize the importance of controlling Pco 2 with respect to the AT when tracheal smooth muscle tone is experimentally altered.

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