Splenic baroreceptors control splenic afferent nerve activity

Area of Science:

• Physiology
• Renal Physiology
• Vascular Physiology

Background:

• Splenic afferent nerve activity (SANA) increases during portal or splenic vein stenosis, leading to reduced renal blood flow via the splenorenal reflex.
• The precise factor stimulating SANA—elevated intrasplenic pressure or reduced blood flow—remained unclear.

Purpose of the Study:

• To investigate whether increased splenic venous pressure or reduced splenic blood flow is the primary stimulus for SANA.
• To elucidate the mechanism activating the splenorenal reflex in venous hypertension models.

Main Methods:

• Experiments were conducted on anesthetized rats.
• Partial occlusion of the splenic artery or vein was used to manipulate splenic pressure and flow.
• Splenic venous and arterial pressures and blood flows were continuously monitored.
• Changes in SANA were measured in response to these occlusions.

Main Results:

• Splenic vein occlusion elevated splenic venous pressure and increased SANA.
• Splenic artery occlusion, matched for blood flow reduction, did not alter splenic venous pressure or SANA.
• A significant linear correlation was found between SANA and splenic venous pressure (r = 0.619, P = 0.008).
• No significant correlation was observed between SANA and splenic venous or arterial blood flow.

Conclusions:

• Splenic venous pressure, rather than blood flow, is the key factor stimulating SANA.
• Elevated splenic venous pressure activates the splenorenal reflex in the context of portal and splenic venous hypertension.