Hepatic denervation chronically elevates arterial pressure in Wistar-Kyoto rats

Area of Science:

• Physiology
• Renal Physiology
• Cardiovascular Regulation

Background:

• Peripheral osmoreceptors are implicated in regulating renal sympathetic nerve activity in response to dietary salt (NaCl).
• The precise role of these osmoreceptors in the long-term control of mean arterial pressure (MAP) is not fully understood.

Purpose of the Study:

• To investigate the hypothesis that denervation of peripheral osmoreceptors increases arterial pressure and causes NaCl-sensitive hypertension.
• To determine the contribution of hepatic osmoreceptors to long-term MAP regulation and salt-induced blood pressure changes.

Main Methods:

• Wistar-Kyoto rats underwent hepatic denervation or sham operation, with telemetry probes implanted for MAP and heart rate monitoring.
• Rats were fed diets with varying NaCl concentrations (0.6%, 8%, or 0.05%) over several weeks.
• Continuous monitoring of MAP and heart rate was performed throughout the dietary interventions.

Main Results:

• Hepatic denervated rats exhibited significantly higher MAP (15+/-1 mm Hg) compared to sham-operated rats on a basal NaCl diet.
• A high NaCl diet did not significantly alter baseline MAP in either group but increased the amplitude of the 24-hour arterial pressure rhythm more in denervated rats.
• A very low NaCl diet did not affect MAP in either denervated or sham-operated rats, though denervated rats maintained higher baseline MAP.

Conclusions:

• Hepatic osmoreceptors play a role in the long-term regulation of arterial pressure in rats.
• These receptors contribute less significantly to the blood pressure elevation typically observed with high dietary NaCl intake.