EVIDENCE THAT DECREASED CARDIAC-OUTPUT IS NOT STIMULUS TO SODIUM RETENTION DURING ACUTE CONSTRICTION OF VENA-CAVA

  • 1 January 1977
    • journal article
    • research article
    • Vol. 89  (4) , 809-816
Abstract
The antinatriuresis during constriction of the TVC [thoracic inferior vena cava] may be due to a decrease in CO [cardiac output]. The effect on Na excretion of comparable reductions in CO was compared by 3 separate methods: TVC constriction, PA [pulmonary artery] occlusion and LV [left ventricle] infarction. Dogs were studied during 10% of body weight saline loading and again after TVC constriction, PA occlusion or LV infarction. CO fell 26 to 31% in all groups; Na excretion was not significantly altered after PA occlusion (474 to 533 .mu.eq/min) or LV infarction (587 to 609 .mu.eq/min) but fell significantly after TVC constriction (504 to 271 .mu.eq/min). Renal and systemic hemodynamics were not different among groups. Acute moderate reduction of CO per se does not cause Na retention. PA and TVC dogs had comparable increments in vena caval pressure but opposite changes in RVEDP [right ventricular end-diastolic pressure] 4 to 0.9 mmHg (TVC) and 0.5 to 9.1 mmHg (PA). [Low-CO congestive heart failure is discussed.].