| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Cardiovascular Center, Departments of Internal Medicine and Pharmacology, University of Iowa College of Medicine, Iowa City, Iowa 52242
We tested the hypothesis that constriction of cerebral
arterioles during acute increases in blood pressure is attenuated by activation of potassium (K+) channels. We tested the
effects of inhibitors of calcium-dependent K+ channels
[iberiotoxin (50 nM) and tetraethylammonium (TEA, 1 mM)] on
changes in arteriolar diameter during acute hypertension. Diameter of
cerebral arterioles (baseline diameter = 46 ± 2 µm, mean ± SE)
was measured using a cranial window in anesthetized rats. Arterial
pressure was increased from a control value of 96 ± 1 mmHg to 130, 150, 170, and 200 mmHg by intravenous infusion of phenylephrine.
Increases in arterial pressure from baseline to 130 and 150 mmHg
decreased the diameter of cerebral arterioles by 5-10%. Greater
increases in arterial pressure produced large increases in arteriolar
diameter (i.e., "breakthrough of autoregulation"). Iberiotoxin or
TEA inhibited increases in arteriolar diameter when arterial pressure
was increased to 170 and 200 mmHg. The change in arteriolar diameter at
200 mmHg was 20 ± 3% and 
1 ± 4% in the absence and
presence of iberiotoxin, respectively. These findings suggest that
calcium-dependent K+ channels attenuate cerebral
microvascular constriction during acute increases in arterial pressure,
and that increases in arteriolar diameter at high levels of arterial
pressure are not simply a passive phenomenon.
cerebral arterioles; iberiotoxin; tetraethylammonium; calcium-dependent potassium channels
This article has been cited by other articles:
|
|
 |
|
  A. G. Euser and M. J. Cipolla Cerebral Blood Flow Autoregulation and Edema Formation During Pregnancy in Anesthetized Rats Hypertension, February 1, 2007; 49(2): 334 - 340. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M.-J. Xie, L.-F. Zhang, J. Ma, and H.-W. Cheng Functional alterations in cerebrovascular K+ and Ca2+ channels are comparable between simulated microgravity rat and SHR Am J Physiol Heart Circ Physiol, September 1, 2005; 289(3): H1265 - H1276. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z.-J. Fu, M.-J. Xie, L.-F. Zhang, H.-W. Cheng, and J. Ma Differential activation of potassium channels in cerebral and hindquarter arteries of rats during simulated microgravity Am J Physiol Heart Circ Physiol, October 1, 2004; 287(4): H1505 - H1515. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Cipolla, L. Vitullo, and J. McKinnon Cerebral artery reactivity changes during pregnancy and the postpartum period: a role in eclampsia? Am J Physiol Heart Circ Physiol, June 1, 2004; 286(6): H2127 - H2132. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. S. Winestone, C. Bonner, and C. W. Leffler Carbon Monoxide as an Attenuator of Vasoconstriction in Piglet Cerebral Arterioles Experimental Biology and Medicine, January 1, 2003; 228(1): 46 - 50. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Sato, M. Tachibana, T. Numata, T. Nishino, and A. Konno Differences in the dynamic cerebrovascular response between stepwise up tilt and down tilt in humans Am J Physiol Heart Circ Physiol, August 1, 2001; 281(2): H774 - H783. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
