AJP - Heart and Circulatory Physiology, Vol 270, Issue 3 974-H980, Copyright © 1996 by American Physiological Society

ARTICLES

Inhaled nitric oxide: diameter response patterns in feline small pulmonary arteries and veins

M. Shirai, A. Shimouchi, A. T. Kawaguchi, K. Sunagawa and I. Ninomiya
Department of Cardiac Physiology, National Cardiovascular Center Research Institute, Suita, Osaka, Japan.

Using an X-ray television system on the in vivo cat lung, we directly measured internal diameter (ID) changes in the small pulmonary arteries and veins (100-1,100 microns ID) in response to 5, 15, and 40 ppm nitric oxide (NO) inhalations. We also measured to what extent 40 ppm NO inhalation can attenuate large ID constrictions at the different serial segments of the small vessels due to unilobar anoxic (0% O2) exposure. Under normoxic conditions, 5-40 ppm NO inhalations significantly increased the ID of both arteries and veins less than approximately 900 microns dose dependently but caused no significant, or only slight, ID increases in the vessels larger than this, if any at all. The ID increase in the serially connected arteries was nonuniform (4-18, 8-28, and 7-35% with 5, 15, and 40 ppm NO inhalations, respectively), whereas that for the veins was relatively uniform (4-9, 6-17, and 7-18% with 5, 15, and 40 ppm NO, respectively). The maximum ID increase occurred in the 200- to 500- and 200- to 700-microns arteries in response to 5-15 and 40 ppm NO, respectively. Unilobar anoxic exposure significantly decreased the ID of the 100- to 700-microns arteries and veins, but not the ID of the other-sized vessels. The ID decrease in the serially connected arteries was nonuniform (13-29%) but relatively uniform in the veins (8-12%). The maximum ID decrease occurred in the 200- to 300-microns arteries. However, adding 40 ppm NO to the lobe completely eradicated the ID decreases at all segments of the arteries and veins and, instead, caused significant ID increase (11-21%) in the arteries and (10-12%) in the veins. The data indicate that, according to dosage, 5-40 ppm NO inhalations cause selective dilation of approximately 100- to 900-microns pulmonary arteries and veins, particularly the 200- to 700-microns arteries. During anoxic exposure, the vasodilator effect of NO is preserved and can completely reverse the marked pulmonary vasoconstriction.

This article has been cited by other articles:

				D. O. Schwenke, J. T. Pearson, K. Kangawa, K. Umetani, and M. Shirai Changes in macrovessel pulmonary blood flow distribution following chronic hypoxia: assessed using synchrotron radiation microangiography J Appl Physiol, January 1, 2008; 104(1): 88 - 96. [Abstract] [Full Text] [PDF]

				D. O. Schwenke, J. T. Pearson, K. Umetani, K. Kangawa, and M. Shirai Imaging of the pulmonary circulation in the closed-chest rat using synchrotron radiation microangiography J Appl Physiol, February 1, 2007; 102(2): 787 - 793. [Abstract] [Full Text] [PDF]

				J. Bentley, D. Rickaby, S. T. Haworth, C. C. Hanger, and C. A. Dawson Pulmonary arterial dilation by inhaled NO: arterial diameter, NO concentration relationship J Appl Physiol, November 1, 2001; 91(5): 1948 - 1954. [Abstract] [Full Text] [PDF]

				M. Nie, H. Kobayashi, M. Sugawara, T. Tomita, K. Ohara, and H. Yoshimura Helium inhalation enhances vasodilator effect of inhaled nitric oxide on pulmonary vessels in hypoxic dogs Am J Physiol Heart Circ Physiol, April 1, 2001; 280(4): H1875 - H1881. [Abstract] [Full Text] [PDF]

				N. Weissmann, A. Tadic, J. Hanze, F. Rose, S. Winterhalder, M. Nollen, R. T. Schermuly, H. A. Ghofrani, W. Seeger, and F. Grimminger Hypoxic vasoconstriction in intact lungs: a role for NADPH oxidase-derived H2O2? Am J Physiol Lung Cell Mol Physiol, October 1, 2000; 279(4): L683 - L690. [Abstract] [Full Text] [PDF]