Bronchial circulation

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This complex circulation system has been proposed to be important for distribution of soluble components of partieles deposited in the eonducting airways (72 Fig. 6). Particles and drugs deposited in the extrapulmonary airways are absorbed into the bronchial circulation, are drained into the right atrium, and are then delivered back to the lung by the pulmonary eirculation, diluted in venous blood coming from the systemic circulation. Drugs can possibly also reach the 

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Barkin, P., W. Jung, P. Pappagianopoulos, C. Balkas, D. Lamborghini, J. Burke, and C. Hales. 1986. The role of the bronchial circulation in production of pulmonary edema in dogs exposed to acrolein in smoke. Amer. Rev. Respir. Dis. 133 A270. 

Two different circulatory systems, the bronchial and the pulmonary, supply the lungs with blood [133], The bronchial circulation is a part of the systemic circulation and is under high pressure. It receives about 1% of the cardiac output and supplies the conducting airways, pulmonary blood vessels and lymph nodes [133], It is important for the distribution of systemically administered drugs to the airways and to the absorption of inhaled drugs from the airways [18]. The pulmonary circulation comprises an extensive low-pressure vascular bed, which receives the entire cardiac output. It perfuses the alveolar capillaries to secure efficient gas exchange and supplies nutrients to the alveolar walls. Anastomoses between bronchial and pulmonary arterial circulations have been found in the walls of medium-sized bronchi and bronchioles [18, 65, 67],... 

Cytokines may exert an important regulatory effect on the expression of adhesion molecules, both on endothelial cells of the bronchial circulation and on airway epithelial cells. Thus IL-4 increases the expression of VCAM-1 on endothelial cells and this may be important in eosinophil and lymphocyte trafficking (Schleimer etal., 1992), and II l and TNFa increase the expression of ICAM-1 in both vascular endothelium and airway epithelium (Tosi etal., 1992). 

Butler, J. (ed.) (1991). The Bronchial Circulation . In the series Lung Biology in Health and Disease (series ed. C. Lenfant). Marcel Dekker, New York. 

Cudkowicz, L. (1968). The Human Bronchial Circulation in Health and Disease . Williams and Wilkins Co., Baltimore. 

Magno, M.G. and Fishman, A.P. (1982). Origin, distribution, and blood flow of bronchial circulation in anesthetized sheep. J. Appl. Physiol. 53, 272-279. 

Persson, C.G.A. (1991b). Plasma exudation from tracheobronchial microvessels in health and disease. In The Bronchial Circulation (ed. J. Butler), pp. 443-473. Marcel Dekker, New York. 

Capsaicin, like the other irritant RCAs, also causes bronchoconstriction, but the mechanism is uncertain. Capsaicin releases substance P that can cause bronchoconstriction directly by activation of specific receptors or by release of histamine or other mediators. It may also cause reflex bronchoconstriction by stimulating C fibers in both pulmonary and bronchial circulation. Therefore, bronchoconstriction may be secondary to substance P release, or to a vagal reflex. The altered neurophysiology of sensory neurons in the airway mucosa induces the release of tachykinins and neurokinin A, which causes neuro-mediated inflammation of the epithelium, airway, blood vessels, glands, and smooth muscles. This leads to bronchoconstriction, mucus secretion, enhanced vascular permeability, and neutrophil chemotaxis. 

Blood vessels supplying the conducting or central airways (i.e., the bronchial circulation) are part of the systemic circulation. By contrast, the blood supply to airways of the respiratory zone involve the pulmonary circulation. The separation of these vascular networks can be almost complete. For example,... 

Figure 5 Diagram of staining of the bronchial circulation in the cat. The bronchial and pulmonary circulations of the cat were perfused separately with aerated physiological salt solution containing bovine serum albumin (4% wt/vol) maintained at 37°C. Perfusates from the bronchial and pulmonary circulations were collected from cannulae positioned in the right and left ventricles, respectively. Infusion of Evans blue dye (30mg/Kg) into the systemic circulation resulted in deep blue staining of the central airways (black) with no staining of the parenchymal tissues (dotted). Further, 75-80% of the dye was collected from the cannula from the right heart.

Bade EM. The anatomy and physiology of tbe bronchial circulation. J Aerosol Med 1996 9 1-6. 

Some technical challenges—severity worse when the lungs remain deflated during ischemic period and when pulmonary and bronchial circulations are occluded together... 

The conducting airways are fed by a second blood supply, the bronchial circulation, which comes from the systemic circulation via the bronchial arteries. Blood returns via the bronchial veins, which empty partly to the systemic veins and partly to the pulmonary veins. The latter case is a circuit that bypasses the lungs entirely and m es the systemic cardiac output slightly huger than the pulmonary cardiac output or lung perfusion Q. 

Deffebach ME, Charan NB, Lakshminarayan S, Butler J. The bronchial circulation-small, but vital attribute of the lung. Am Rev Respir Dis 1987 135 463-481. 

Wietholt C, Molthen RC, Haworth ST, Dawson CA, Roerig DL, Clough AV. Quantification of bronchial circulation perfusion in rats. In Amani AA, Manduca A, eds. Physiology, Function, and Structure from Medical Images. Vol. 5370. SPIE Proceedings, 2004. 

The biological actions of capsaicin are primarily attributable to release of the neuropeptide substance P, calcitonin gene-related peptide (CGRP), and neurokinin A from sensory neurons. These transmitters from primary sensory neurons communicate witir other cell types. They produce alterations in the airway mucosa and neurogenic inflammation of the respiratory epithelium, airway blood vessels, glands, and smooth muscle. Alterations in multiple effector organs lead to bronchoconstriction, increased vascular permeability, edema of the tracheobronchial mucosa, elevated mucosal secretion, and neutrophil chemotaxis (Tominack and Spyker, 1987). Capsaicin-induced effects of bronchoconstriction, vasodilation, and plasma protein extravasation are mediated by substance P. In addition, substance P can cause bronchoconstriction through stimulation of c-fibers in pulmonary and bronchial circulation. 

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