AJP - Heart AJP: Cell Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Am J Physiol Heart Circ Physiol (December 19, 2002). doi:10.1152/ajpheart.00680.2002
This Article
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
284/4/H1182    most recent
00680.2002v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Teoh, H.
Right arrow Articles by Ward, M. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Teoh, H.
Right arrow Articles by Ward, M. E.
Submitted on August 1, 2002
Accepted on December 10, 2002

Increased Myofibrillar Protein Phosphatase-1 Activity Impairs Rat Aortic Smooth Muscle Activation After Hypoxia

Hwee Teoh1, Mary E. Zacour2, Avraham D. Wener1, Lakshman Gunaratnam1, and Michael E. Ward1*

1 Medicine, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada
2 Medicine, Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada

* To whom correspondence should be addressed. E-mail: wardm{at}smh.toronto.on.ca.

We hypothesized that increased myofibrillar type 1 phosphatase (PP1) catalytic activity contributes to impaired aortic smooth muscle contraction after hypoxia. Our results show that inhibition of PP1 activity with microcystin-LR (50 nmol/L) or okadaic acid (100 nmol/L) increased phenylephrine- and KCl-induced contraction to a greater extent in aortic rings from rats exposed to hypoxia (10% O2) for 48 hours than in rings from normoxic animals and restored the level of phosphorylation of the 20 kDa myosin light chain (LC20) during maximal phenylephrine-induced contraction to that observed in the normoxic control group. Myofibrillar PP1 activity was greater in aortas from rats exposed to hypoxia than in normoxic rats (p<0.05). Levels of the targeting protein (MYPT1) that mediates myofibrillar localization of PP1 activity were increased in aortas from hypoxic rats (193[plusmn]28% of the normoxic control value, p<0.05) and in human aortic smooth muscle cells after hypoxic (1% O2) incubation (182[plusmn]18% of the normoxic control value, p<0.05). Aortic levels of myosin light chain kinase were similar in normoxic and hypoxic groups. We conclude that following hypoxia, increased MYPT1 protein expression and myofibrillar PP1 activity impair aortic vasoreactivity through enhanced dephosphorylation of LC20.




This article has been cited by other articles:


Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
J. B. Ray, S. Arab, Y. Deng, P. Liu, L. Penn, D. W. Courtman, and M. E. Ward
Oxygen regulation of arterial smooth muscle cell proliferation and survival
Am J Physiol Heart Circ Physiol, February 1, 2008; 294(2): H839 - H852.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
J. Z. He, A. Quan, Y. Xu, H. Teoh, G. Wang, J. E. Fish, B. M. Steer, S. Itohara, P. A. Marsden, S. T. Davidge, et al.
Induction of matrix metalloproteinase-2 enhances systemic arterial contraction after hypoxia
Am J Physiol Heart Circ Physiol, January 1, 2007; 292(1): H684 - H693.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
V. Govindaraju, H. Teoh, Q. Hamid, P. Cernacek, and M. E. Ward
Interaction between endothelial heme oxygenase-2 and endothelin-1 in altered aortic reactivity after hypoxia in rats
Am J Physiol Heart Circ Physiol, February 1, 2005; 288(2): H962 - H970.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Visit Other APS Journals Online
Copyright © 1976 by the American Physiological Society.