Cardiopulmonary receptors (CPR) locate in the junction of great veins (IVC/SVC/PV) to atria. They are also known as low-pressure receptors. They detect the increase of preload to atria.
Statement 1: Sense of venous blood volume load (Bainbridge reflex)
Greater preload -> activation of CPR -> sympathetic activation -> tachycardia -> empty atria more quickly
Statement 2: However, when thinking of the importance of maintaining arterial blood pressure:
Greater preload (IV infusion, etc) -> predict higher cardiac output (Frank-Starling) -> predict increase arterial blood pressure -> inhibition of sympathetic tone in advance so that higher preload will not cause much change in arterial blood pressure
It seems that these two statements are opposite. Can someone clarify this for me? Thank you very much.
My guess is that arterial blood pressure is still the priority, if blood pressure is high, sympathetic tone will be depressed (by high-pressure receptors at aortic arch, carotid sinus) to an extent that is greater than activation of sympathetic tone by CPR. If blood pressure is within normal limit or low, bainbridge reflex still occurs as usual.
Website that supports statement 1:
Website that supports statement 2: