Right atrium mediates a vasomotor reflex.
To examine the role of right atrial receptors in mediating reflex vascular responses we measured, in cats anesthetized with chloralose/urethan, changes in mean arterial pressure (MAP) in response to volume pulsation of the right atrium (+/- 1 ml, 1 Hz). Changes in MAP were measured 1) with pressure in the carotid arteries normal and vagus nerves intact: right atrial pulsation led to a very small and transient fall in MAP; 2) with pressure in the carotid arteries at 75 mmHg and the vagus nerves intact: right atrial pulsation led to a larger and sustained fall in MAP; 3) with pressure in the carotid arteries at 75 mmHg and the vagus nerves cooled or sectioned bilaterally: right atrial pulsation of the right atrium led only to a very small and transient fall in MAP. These data suggest strongly that signals from right atrial receptors traveling in the vagus nerves mediate a reflex change in MAP that is normally masked by signals from carotid receptors.
D000818:Animals; D016275:Atrial Function; D001794:Blood Pressure; D002346:Carotid Sinus / Q000502:physiology; D002415:Cats; D003201:Computers; D003714:Denervation; D004558:Electric Stimulation; D006321:Heart / Q000502:physiology*; D006325:Heart Atria / Q000294:innervation; D006329:Heart Conduction System; D008465:Mechanoreceptors / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology; D012018:Reflex; D014630:Vagus Nerve / Q000502:physiology