Effect of acute cold exposure on lung perfusion and tracheal smooth muscle contraction in rabbit.
Acute exposure to cold temperature can affect the respiratory system of those exposed to extreme weather and induces asthma in asthmatic patients. However, the effect on lung perfusion and the pulmonary circulation was not addressed in any previous study. The present study investigates the effects of acute cold exposure on tracheal smooth muscle and lung perfusion. New Zealand White rabbits were used in these experiments. For in vitro experiments, isolated tracheal segments were suspended in organ baths containing Krebs' solution for isometric tension recording. Tissue response to cooling from 37 to 4°C was examined. For in vivo experiments, the rabbits were kept in a cold room (4°C) for 1 h. Lung perfusion scintigraphy was performed at the end of this period. Each rabbit was injected with 74 MBq (2 mCi) technetium-99m macroaggregated ((99m)Tc MAA). Perfusion studies were done by using Gamma camera equipped with a low-energy, high-resolution, parallel-hole collimator interfaced with a computer. Static images were acquired 5 min after administration of the radiotracer. Cooling induced a rapid and reproducible contraction in the tracheal smooth muscle. Rabbits exposed to cold temperature had lesser lung perfusion than controls using radionuclide perfusion study. Our results highlight the response of tracheal muscle and pulmonary circulation to cold exposure. These results indicate that cooling induced contraction of the trachea and decreased pulmonary circulation and lung perfusion. This summation of acute cooling for tracheal smooth muscle and pulmonary circulation seems to be the reason for the severe cooling-induced contraction.
Khadadah
Mousa
M
Department of Medicine, Faculty of Medicine, Kuwait University, Kuwait City, Kuwait.
Mustafa
Seham
S
Elgazzar
Abdelhamid
A
D000818:Animals; D003080:Cold Temperature; D008168:Lung / Q000000981:diagnostic imaging / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology*; D010477:Perfusion; D011817:Rabbits; D011877:Radionuclide Imaging; D014132:Trachea / Q000000981:diagnostic imaging / Q000502:physiology*
Rev Port Pneumol. 2007 Nov-Dec;13(6):775-87
18183329
Pharmacol Res. 1999 Feb;39(2):125-36
10072703
Chest. 2002 Jun;121(6):1806-11
12065342
Can Respir J. 2007 Jul-Aug;14(5):285-91
17703244
J Asthma. 2007 Mar;44(2):143-7
17454330
Respiration. 1970;27(5):431-46
5477527
J Allergy Clin Immunol. 2006 Nov;118(5):1126-32
17088139
Pharmacol Res. 1999 Feb;39(2):113-23
10072702
Postgrad Med J. 1973 Jul;49(573):487-502
4602128
Clin Exp Allergy. 2006 Jan;36(1):26-31
16393262
Curr Opin Pharmacol. 2009 Jun;9(3):287-96
19297247
Chest. 1996 Sep;110(3):632-6
8797403
J Appl Physiol. 1969 Jan;26(1):101-4
5762860
J Appl Physiol Respir Environ Exerc Physiol. 1979 Mar;46(3):484-90
438016
Respiration. 2004 Jul-Aug;71(4):428
15316222
Int J Circumpolar Health. 2007 Apr;66(2):91-100
17515249
Clin Sci. 1967 Oct;33(2):355-64
6058433
Respir Med. 2006 Sep;100(9):1633-41
16446080
Chest. 1982 Jun;81(6):675-80
7075300