|
|
||||||||
Journal of Applied Physiology, Vol 78, Issue 4 1404-1411, Copyright © 1995 by American Physiological Society
ARTICLES |
P. S. Wilson, P. L. Khimenko, J. W. Barnard, T. M. Moore and A. E. Taylor
Department of Physiology, University of South Alabama School of Medicine, Mobile 36688, USA.
The present study investigated the ability of atropine and different muscarinic receptor subtypes to affect acetylcholine (ACh)-induced bronchoconstriction and vasodilation in the isolated rat lung model. ACh (10(-7) M) given after U-46619 decreased total (RT), precapillary, and postcapillary vascular resistances and increased peak airway pressure. Atropine (20 microM) decreased RT and precapillary and postcapillary vascular resistances and blocked ACh-induced increases in peak airway pressure. The M1-selective agonist McN-A-343 (1.3 x 10(-5) M) decreased RT from 40.27 +/- 2.98 to 29.20 +/- 2.81 cmH2O.l-1.min-100 g lung wt (P = 0.01), and ACh caused no further dilation. The M1-selective antagonist pirenzepine (1.6 x 10(-6) M) blocked ACh-induced vasodilation. The M2-selective antagonist gallamine (7.5 x 10(-7) M) decreased RT from 45.50 +/- 3.19 to 34.86 +/- 1.25 cmH2O.l-1.min.100 g lung wt (P < 0.05), and after gallamine, ACh further decreased RT to 28.59 +/- 1.75 cmH2O.l-1.min.100 g lung wt (P < 0.01). Neither the selective muscarinic agonists nor antagonists affected peak airway pressures. We conclude that ACh-induced vasodilation in isolated rat lungs preconstricted with U-46619 is mediated by M1 receptors. Atropine-induced vasodilation in this model is mediated through the inhibition of the M2 receptor. We postulate that this represents either a blockade of postganglionic receptors, permitting release of vasodilator substances from local nerve terminals, or a direct vasodilatory effect on the vascular smooth muscle.
This article has been cited by other articles:
![]() |
J. Belik, J. Pan, R. P. Jankov, and A. K. Tanswell Bronchial epithelium-associated pulmonary arterial muscle relaxation in the rat is absent in the fetus and suppressed by postnatal hypoxia Am J Physiol Lung Cell Mol Physiol, February 1, 2005; 288(2): L384 - L389. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |