AJP - Regu Ad Instruments
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
 QUICK SEARCH:   [advanced]


     


Am J Physiol Regul Integr Comp Physiol (September 30, 2009). doi:10.1152/ajpregu.00551.2009
This Article
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
297/6/R1777    most recent
00551.2009v1
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
Google Scholar
Right arrow Articles by Yavorcik, K. J
Right arrow Articles by Yates, B. J.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Yavorcik, K. J
Right arrow Articles by Yates, B. J.
Submitted on August 31, 2009
Revised on September 29, 2009
Accepted on September 29, 2009

Effects of Postural Changes and Removal of Vestibular Inputs on Blood Flow to and from the Hindlimb of Conscious Felines

Kevin J Yavorcik1, Derek A Reighard1, Sunil P Misra1, Lucy A Cotter, Stephen P Cass2, Tim D. Wilson3, and Bill J. Yates1*

1 University of Pittsburgh
2 University of Colorado Health Sciences Center
3 University of Western Ontario

* To whom correspondence should be addressed. E-mail: byates{at}pitt.edu.

Considerable data show that the vestibular system contributes to regulating blood pressure. Prior studies reported that lesions that eliminate inputs from the inner ears attenuate the vasoconstriction that ordinarily occurs in the hindlimbs of conscious cats during head-up rotations. These data led to the hypothesis that labyrinthine-deficient animals would experience considerable lower body blood pooling during head-up postural alterations. The present study tested this hypothesis by comparing blood flow though the femoral artery and vein of conscious felines during 20°-60° head-up tilts from the prone position before and after the removal of vestibular inputs. In vestibular intact animals, venous return from the hindlimb dropped considerably at the onset of head-up tilts, and at 5 sec following the initiation of 60° rotations was 66% lower than when the animals were prone. However, after the animals were maintained in the head-up position for another 15 sec, venous return was just 33% lower than before the tilt commenced. At the same time point, arterial inflow to the limb had decreased 32% from baseline, such that the decrease in blood flow out of the limb due to the force of gravity was precisely matched by a reduction in blood reaching the limb. After vestibular lesions, the decline in femoral artery blood flow that ordinarily occurs during head-up tilts was attenuated, such that more blood flowed into the leg. Contrary to expectations, in most animals venous return was facilitated such that no more blood accumulated in the hindlimb than when labyrinthine signals were present. These data show that peripheral blood pooling is unlikely to account for the fluctuations in blood pressure that can occur during postural changes of animals lacking inputs from the inner ear. Instead, alterations in total peripheral resistance following vestibular dysfunction could affect the regulation of blood pressure.







HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Visit Other APS Journals Online
Copyright © 2009 by the American Physiological Society.