Document Detail


Coupling-induced complexity in nephron models of renal blood flow regulation.
MedLine Citation:
PMID:  20147606     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Tubular pressure and nephron blood flow time series display two interacting oscillations in rats with normal blood pressure. Tubuloglomerular feedback (TGF) senses NaCl concentration in tubular fluid at the macula densa, adjusts vascular resistance of the nephron's afferent arteriole, and generates the slower, larger-amplitude oscillations (0.02-0.04 Hz). The faster smaller oscillations (0.1-0.2 Hz) result from spontaneous contractions of vascular smooth muscle triggered by cyclic variations in membrane electrical potential. The two mechanisms interact in each nephron and combine to act as a high-pass filter, adjusting diameter of the afferent arteriole to limit changes of glomerular pressure caused by fluctuations of blood pressure. The oscillations become irregular in animals with chronic high blood pressure. TGF feedback gain is increased in hypertensive rats, leading to a stronger interaction between the two mechanisms. With a mathematical model that simulates tubular and arteriolar dynamics, we tested whether an increase in the interaction between TGF and the myogenic mechanism can cause the transition from periodic to irregular dynamics. A one-dimensional bifurcation analysis, using the coefficient that couples TGF and the myogenic mechanism as a bifurcation parameter, shows some regions with chaotic dynamics. With two nephrons coupled electrotonically, the chaotic regions become larger. The results support the hypothesis that increased oscillator interactions contribute to the transition to irregular fluctuations, especially when neighboring nephrons are coupled, which is the case in vivo.
Authors:
Jakob L Laugesen; Olga V Sosnovtseva; Erik Mosekilde; Niels-Henrik Holstein-Rathlou; Donald J Marsh
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-02-10
Journal Detail:
Title:  American journal of physiology. Regulatory, integrative and comparative physiology     Volume:  298     ISSN:  1522-1490     ISO Abbreviation:  Am. J. Physiol. Regul. Integr. Comp. Physiol.     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-03-23     Completed Date:  2010-04-15     Revised Date:  2013-05-30    
Medline Journal Info:
Nlm Unique ID:  100901230     Medline TA:  Am J Physiol Regul Integr Comp Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  R997-R1006     Citation Subset:  IM    
Affiliation:
Department of Molecular Pharmacology, Brown University, Biomedical Center B-3, Providence, RI 02912, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Arterioles / physiology
Blood Flow Velocity
Blood Pressure / physiology*
Disease Models, Animal
Feedback
Homeostasis / physiology
Hypertension / physiopathology
Kidney Glomerulus / physiology
Kidney Tubules / blood supply,  physiology
Membrane Potentials / physiology*
Models, Biological
Nephrons / physiology*
Oscillometry
Rats
Renal Circulation / physiology*
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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