Domestic Swine in Physiological Research. VI. Effect of Splenic Erythrocyte Sequestration on Blood Volume Measurements in Conscious Immature Pigs.

When estimated by the dilution of 51 Cr-labelled erythrocytes under near-basal conditions, immature splenectomized pigs N20 had a circulating erythrocyte volume of 17.8 or - 1.64 S.D. mlkg. At an assumed body to large vessel hematocrit BHLH ratio of 1.0 plasma volume was 42.8 or - 2.69 mlkg and blood volume 60.6 or - 3.30 mlkg. At an assumed BHLH ratio of 0.9 plasma volume was 49.6 or - 3.12 mlkg and blood volume was 67.3 or - 3.67 mlkg. Sham-operated pigs N20 had a circulating erythrocyte volume of 16.2 or - 1.39 mlkg, and at a BHLH ratio of 1.0 a plasma volume was 44.4 or - 2.96 and a blood volume was 60.5 or - 3.78 mlkg at BHLH ratio of 0.9 plasma volume was 51.1 or - 3.42 mlkg and blood volume was 67.2 or - 4.12 mlkg. Kinetic analysis of early 51 Cr loss from the circulating blood of the sham-operated pigs indicated a splenic erythrocyte sequestration of 4.51 or - 0.89 mlkg and a t-12 of 9.67 or - 1.93 minutes for splenic erythrocyte turnover. Epinephrine injection 0.025 mgkg caused rapid mobilization of splenic erythrocytes in sham-operated pigs N6 with a hematocrit rise from 0.27 or - 0.01 to 0.35 or - 0.02. Similar results were obtained in sham-operated pigs N9 subjected to physical restraint.