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Renal myogenic response: kinetic attributes and physiological role
Rodger Loutzenhiser1, Anil Bidani, Lisa Chilton
1Smooth Muscle Research Group, Department of Pharmacology and Therapeutics, The University of Calgary, Calgary, Alberta, Canada. rloutzen@ucalgary.ca
Circulation Research
|June 29, 2002
Summary
The afferent arteriole
Area of Science:
- Physiology
- Nephrology
Background:
- The afferent arteriole's myogenic response is crucial for renal autoregulation.
- Previous understanding suggested its primary role in maintaining constant glomerular capillary pressure.
Purpose of the Study:
- To investigate the kinetic attributes of the afferent arteriole's myogenic response.
- To develop a mathematical model of renal autoregulation.
- To challenge the established view on the myogenic response's function.
Main Methods:
- Utilized an in vitro perfused hydronephrotic rat kidney model.
- Developed a mathematical model combining vasoconstriction, vasodilation, and steady-state diameter changes.
- Constructed transfer functions using sinusoidal pressure waves and compared with data from conscious rats.
Main Results:
- Observed reduced gain and increased phase at 0.2-0.3 Hz in both model and conscious rats.
- Model predicted and experiments confirmed sustained vasoconstriction above the myogenic range, dependent on peak pressure.
- Elevated systolic pressure induced vasoconstriction even with reduced mean pressure.
Conclusions:
- The renal myogenic response primarily protects against elevated systolic pressures, not solely maintaining constant glomerular pressure.
- Afferent arteriole kinetics adjust tone to systolic pressure changes at pulse rate.
- The mechanism protects the glomerulus from pulsatile blood pressure power.