Document Detail


Influence of hypercapnic vasodilation on cerebrovascular autoregulation and pial arteriolar bed resistance in piglets.
MedLine Citation:
PMID:  18436696     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Changes in both pial arteriolar resistance (PAR) and simulated arterial-arteriolar bed resistance (SimR) of a physiologically based biomechanical model of cerebrovascular pressure transmission, the dynamic relationship between arterial blood pressure and intracranial pressure, are used to test the hypothesis that hypercapnia disrupts autoregulatory reactivity. To evaluate pressure reactivity, vasopressin-induced acute hypertension was administered to normocapnic and hypercapnic (N = 12) piglets equipped with closed cranial windows. Pial arteriolar diameters were used to compute arteriolar resistance. Percent change of PAR (%DeltaPAR) and percent change of SimR (%DeltaSimR) in response to vasopressin-induced acute hypertension were computed and compared. Hypercapnia decreased cerebrovascular resistance. Indicative of active autoregulatory reactivity, vasopressin-induced hypertensive challenge resulted in an increase of both %DeltaPAR and %DeltaSimR for all normocapnic piglets. The hypercapnic piglets formed two statistically distinct populations. One-half of the hypercapnic piglets demonstrated a measured decrease of both %DeltaPAR and %DeltaSimR to pressure challenge, indicative of being pressure passive, whereas the other one-half demonstrated an increase in these percentages, indicative of active autoregulation. No other differences in measured variables were detectable between regulating and pressure-passive piglets. Changes in resistance calculated from using the model mirrored those calculated from arteriolar diameter measurements. In conclusion, vasodilation induced by hypercapnia has the potential to disrupt autoregulatory reactivity. Our physiologically based biomechanical model of cerebrovascular pressure transmission accurately estimates the changes in arteriolar resistance during conditions of active and passive cerebrovascular reactivity.
Authors:
Nithya Narayanan; Charles W Leffler; Michael L Daley
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2008-04-24
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  105     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2008 Jul 
Date Detail:
Created Date:  2008-07-21     Completed Date:  2008-09-03     Revised Date:  2014-09-22    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  152-7     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Algorithms
Animals
Arterioles / physiology
Biomechanical Phenomena
Blood Gas Analysis
Blood Pressure / physiology
Cerebrovascular Circulation / physiology*
Homeostasis / physiology*
Hypercapnia / physiopathology*
Models, Biological
Models, Statistical
Swine
Vascular Resistance / physiology*
Vasoconstrictor Agents / pharmacology
Vasodilation / physiology*
Vasopressins / pharmacology
Grant Support
ID/Acronym/Agency:
R01 HL034059/HL/NHLBI NIH HHS; R37 HL042851/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Vasoconstrictor Agents; 11000-17-2/Vasopressins
Comments/Corrections

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