title: Evidence that decreased cardiac output is not the stimulus to sodium retention during acute constriction of the vena cava.
abstract: It has been proposed that the antinatriuresis during constriction of the TVC is due to a decrease in CO. We have compared the effect on sodium excretion of comparable reductions in CO by three separate methods: TVC constriction, PA occlusion, and LV 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; sodium excretion was not significantly altered after PA occlusion (474 to 533 micronEq/min.) or LV infarction (587 to 609 micronEq/min.) but fell significantly after TVC constriction (504 to 271 micronEq/min.). Renal and systemic hemodynamoderate reduction of CO per se does not cause sodium retention. PA and TVC dogs had comparable increments in vena caval pressure but opposite changes in RVEDP; 4 to 0.9 mm. Hg (TVC) and 0.5 to 9.1 mm. Hg (PA).
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002302:Cardiac Output; D003250:Constriction; D004285:Dogs; D005260:Female; D009200:Myocardial Contraction; D009203:Myocardial Infarction; D011651:Pulmonary Artery; D012964:Sodium / Q000652:urine*; D014683:Vena Cava, Superior
chemical_list: D012964:Sodium