|
|
||||||||
1 Department of Neonatology, CHRU de Lille, France; and 2 Department of Pediatrics, Pediatric Heart Lung Center, University of Colorado School of Medicine, Denver, Colorado 80218-1088
We hypothesized that altered vasoreactivity in perinatal pulmonary hypertension (PH) is characterized by abnormal responses to hemodynamic stress, including the loss of flow-induced vasodilation and an augmented myogenic response. Therefore, we studied the acute hemodynamic effects of brief compression of the ductus arteriosus (DA) in control fetal lambs and in lambs during exposure to chronic PH. In both groups, acute DA compression decreased pulmonary vascular resistance (PVR) by 20% at baseline (day 0). After 2 days of hypertension, acute DA compression paradoxically increased PVR by 50% in PH lambs, whereas PVR decreased by 25% in controls. During the 8-day study period, PVR increased during acute DA compression in PH lambs, whereas acute DA compression continued to cause vasodilation in controls. Brief treatment with the nitric oxide (NO) synthase inhibitor nitro-L-arginine (L-NA) increased basal PVR in control but not PH lambs, suggesting decreased NO production in PH lambs. Chronic hypertension increased the myogenic response after L-NA in PH lambs, whereas the myogenic response remained unchanged in controls. The myogenic response was inhibited by nifedipine in PH lambs, suggesting that the myogenic response is dependent upon the influx of extracellular calcium. We conclude that chronic PH impairs flow-induced vasodilation and increases the myogenic response in fetal lung. We speculate that decreased NO signaling and an augmented myogenic response contributes to abnormal vasoreactivity in PH.
myogenic response; nitric oxide; pulmonary circulation; persistent pulmonary hypertension of the newborn; smooth muscle; calcium channels
This article has been cited by other articles:
![]() |
P. Tourneux, M. Chester, T. Grover, and S. H. Abman Fasudil inhibits the myogenic response in the fetal pulmonary circulation Am J Physiol Heart Circ Physiol, October 1, 2008; 295(4): H1505 - H1513. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. R. S. Broughton, B. R. Walker, and T. C. Resta Chronic hypoxia induces Rho kinase-dependent myogenic tone in small pulmonary arteries Am J Physiol Lung Cell Mol Physiol, April 1, 2008; 294(4): L797 - L806. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. J. Sandoval, E. R. Injeti, J. M. Williams, W. T. Georthoffer, and W. J. Pearce Myogenic contractility is more dependent on myofilament calcium sensitization in term fetal than adult ovine cerebral arteries Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H548 - H556. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Larrue, S. Jaillard, M. Lorthioir, X. Roubliova, G. Butrous, T. Rakza, H. Warembourg, and L. Storme Pulmonary vascular effects of sildenafil on the development of chronic pulmonary hypertension in the ovine fetus Am J Physiol Lung Cell Mol Physiol, June 1, 2005; 288(6): L1193 - L1200. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |