Interaction of myogenic mechanisms and hypoxic dilation in rat middle cerebral arteries. Am J Physiol Heart Circ Physiol 2002 Dec;283(6):H2276-81
Date
10/22/2002Pubmed ID
12388266DOI
10.1152/ajpheart.00635.2002Scopus ID
2-s2.0-0036890217 (requires institutional sign-in at Scopus site) 21 CitationsAbstract
The goal of this study was to determine how myogenic responses and vascular responses to reduced Po(2) interact to determine vascular smooth muscle (VSM) transmembrane potential and active tone in isolated middle cerebral arteries from Sprague-Dawley rats. Stepwise elevation of transmural pressure led to depolarization of the VSM cells and myogenic constriction, and reduction of the O(2) concentration of the perfusion and superfusion reservoirs from 21% O(2) to 0% O(2) caused vasodilation and VSM hyperpolarization. Myogenic constriction and VSM depolarization in response to transmural pressure elevation still occurred at reduced Po(2). Arterial dilation in response to reduced Po(2) was not impaired by pressure elevation but was significantly reduced at the lowest transmural pressure (60 mmHg). However, the magnitude of VSM hyperpolarization was unaffected by transmural pressure elevation. This study demonstrates that myogenic activation in response to transmural pressure elevation does not override hypoxic relaxation of middle cerebral arteries and that myogenic responses and hypoxic relaxation can independently regulate vessel diameter despite substantial changes in the other variable.
Author List
Liu Y, Harder DR, Lombard JHMESH terms used to index this publication - Major topics in bold
AnimalsBlood Pressure
Calcium
Hypoxia
In Vitro Techniques
Male
Membrane Potentials
Middle Cerebral Artery
Muscle, Smooth, Vascular
Perfusion
Rats
Rats, Sprague-Dawley
Vascular Patency
Vasoconstriction
Vasodilation
