title: Effect of increased oxygen affinity and anemia on cardiac output and its distribution.
abstract: Effect of increased blood O2 affinity on cardiac output and its distribution was studied in conscious sedated rats by the microsphere-reference sample method. After a preliminary measurement of cardiac output and its distribution, rats were exchange transfused with normal blood or low-P50 (PO2 at which hemoglobin is half-saturated with O2) blood; other groups were made anemic with and without a simultaneous reduction in P50. Reduction in P50 from 38 to 17 Torr did not change cardiac output, pulse, or blood pressure but caused, after allowance for changes in controls, a 102% increase in coronary blood flow and an 88% increase in cerebral blood flow. Anemia (hematocrit = 22%) produced similar changes in coronary and cerebral flow. When anemia was combined with a 12-Torr reduction in P50, coronary and cerebral flow increased by 297 and 209%, respectively. These increases in coronary and cerebral flow were not attributable to increased cardiac work or hypercapnia. It is concluded that a left shift of the O2 dissociation curve induces increased blood flow to brain and heart, probably in compensation for decreased tissue O2 pressure.
mesh_terms: D000740:Anemia / Q000503:physiopathology*; D000818:Animals; D001921:Brain / Q000098:blood supply; D002302:Cardiac Output; D006400:Hematocrit; D008297:Male; D010100:Oxygen / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012079:Renal Circulation; D013154:Spleen / Q000098:blood supply; D014018:Tissue Distribution
chemical_list: D010100:Oxygen