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This Article Full Text Full Text (PDF) All Versions of this Article: 295/5/R1502    most recent 00490.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Williamson, G. A. Articles by Bidani, A. K. Search for Related Content PubMed PubMed Citation Articles by Williamson, G. A. Articles by Bidani, A. K.

HEMODYNAMICS AND CARDIORENAL INTEGRATION

Systolic and mean blood pressures and afferent arteriolar myogenic response dynamics: a modeling approach

¹Department of Electrical and Computer Engineering, Illinois Institute of Technology, Chicago; ³Department of Internal Medicine, Loyola University Medical Center and Edward Hines, Jr., Veterans Affairs Hospital, Maywood, Illinois; and ²Smooth Muscle Research Group, Univerity of Calgary, Calgary, Alberta, Canada

Submitted 6 July 2007 ; accepted in final form 1 August 2008

The afferent arteriolar myogenic response contributes to the autoregulation of renal blood flow (RBF) and glomerular filtration rate (GFR), and plays an essential role in protecting the kidney against hypertensive injury. Systolic blood pressure (SBP) is most closely linked to renal injury, and a myogenic response coupled to this signal would facilitate renal protection, whereas mean blood pressure (MBP) influences RBF and GFR. The relative role of SBP vs. MBP as the primary determinant of myogenic tone is an area of current controversy. Here, we describe two mathematical models, Model-Avg and Model-Sys, that replicate the different delays and time constants of vasoconstrictor and vasodilator phases of the myogenic responses of the afferent arteriole. When oscillating pressures are applied, the MBP determines the magnitude of the myogenic response of Model-Avg, and the SBP determines the response of Model-Sys. Simulations evaluating the responses of both models to square-wave pressure oscillations and to narrow pressure pulses show decidedly better agreement between Model-Sys and afferent arteriolar responses observed in cortical nephrons in the in vitro hydronephrotic kidney model. Analysis showing that the difference in delay times of the vasoconstrictor and vasodilator phases determines the frequency range over which SBP triggers Model-Sys's response was confirmed with simulations using authentic blood pressure waveforms. These observations support the postulate that SBP is the primary determinant of the afferent arteriole's myogenic response and indicate that differences in the delays in initiation vs. termination of the response, rather than in time constants, are integral to this phenomenon.

autoregulation; hypertension; kidney