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Afferent renal nerves and hypertension
1Department of Medicine, University of Alabama, Birmingham 35294.
Summary
Intrarenal adenosine stimulates renal nerves, increasing sympathetic activity and blood pressure in a rat hypertension model. Blocking this adenosine reflex lowers blood pressure, suggesting a spinal reflex mechanism.
Area of Science:
- Nephrology
- Cardiovascular Physiology
- Neuroendocrinology
Background:
- Adenosine-sensitive nerve endings in the renal pelvis can elevate sympathetic activity, contributing to hypertension.
- In one-kidney, one-clip (1-1) hypertensive rats, reduced intrarenal adenosine lowers sympathetic activity and arterial pressure.
- These findings implicate intrarenal adenosine as a key stimulus for afferent renal nerve activity in 1-1 hypertension.
Purpose of the Study:
- To investigate the intrarenal adenosine-mediated hypertensive reflex.
- To determine the neural pathways involved in this reflex.
- To elucidate the role of adenosine in maintaining 1-1 hypertension.
Main Methods:
- Infusion of xylocaine into the renal pelvis.
- Selective renal deafferentation.
- Adrenal demedullation.
- Spinal cord transection at the T6 level.
- Measurements of peripheral sympathetic nervous system activity and arterial pressure in rats.
Main Results:
- The intrarenal adenosine hypertensive reflex was abolished by renal pelvic xylocaine, renal deafferentation, and adrenal demedullation.
- The reflex remained intact after spinal cord transection (T6).
- These interventions were effective in both normotensive and hypertensive animals.
Conclusions:
- Adenosine-sensitive afferent renal nerves in the renal pelvis contribute to sympathoadrenal activity and maintain 1-1 hypertension.
- The intrarenal adenosine-hypertensive response likely involves a spinal-level reflex in rats.
- Targeting this adenosine-renal nerve pathway may offer therapeutic potential for hypertension.