Key Points
- To determine whether loading or unloading right heart baroreceptors alters the secretion of vasopressin, ACTH, and renin during sustained arterial hypotension.
- Conscious, chronically instrumented dogs were implanted with inflatable vascular cuffs around the pulmonary artery (PA) and thoracic inferior vena cava (IVC).
- Mean arterial pressure (MAP) was reduced 10% to 20% in two protocols (n=5 and n=4) using PA or IVC constriction while independently manipulating right atrial pressure (RAP) with the alternate cuff.
- Inducing hypotension via PA constriction reduced left atrial pressure (LAP), elevated RAP, and significantly increased plasma AVP, ACTH, atrial natriuretic peptide (ANP), and plasma renin activity (PRA) (P < 0.05).
- Restoring RAP to baseline during continued PA constriction significantly decreased ANP but had no effect on MAP, LAP, plasma AVP, ACTH, or PRA.
- Raising RAP from 6.3 ± 1.3 mmHg below control to 3.5 ± 1.0 mmHg above control during IVC-induced hypotension produced no changes in plasma AVP, ACTH, or PRA.
Structured PICO
PPopulation9 chronically instrumented conscious dogs prepared with inflatable cuffs around the pulmonary artery (PA) and the thoracic inferior vena cava (IVC).
IInterventionIncreasing or decreasing right heart baroreceptor load via constriction of the pulmonary artery or inferior vena cava during sustained arterial hypotension.
CComparatorBaseline/control state prior to manipulation.
OOutcomePlasma levels of arginine vasopressin (AVP), adrenocorticotropic hormone (ACTH), and plasma renin activity (PRA).surrogate
In a canine model, changes in right atrial pressure do not modulate the secretion of AVP, ACTH, or renin during sustained arterial hypotension.