RATE OF UPTAKE OF CO BY HEMOGLOBIN IN PIG ERYTHROCYTES AS A FUNCTION OF PO2

This study was initiated to obtain data on the rate of carbon monoxide (CO) uptake (Theta(CO)) by hemoglobin in pig erythrocytes to derive, in a later study, the pulmonary capillary blood volume (Qc) in pigs fr om the Roughton-Forster relationship. Blood from five different female pigs was used. The Theta(CO), the milliliters of CO taken up by 1 ml of whole blood per minute per Torr CO tension, was determined on each blood sample with a continuous-flow rapid-mixing apparatus and double- beam spectrophotometry at 37 degrees C and pH 7.4 at four or five diff erent-PO2 values. Because the individual regression lines of Theta(CO) vs. PO2 were not significantly different, a common regression equatio n was calculated: 1/Theta(CO) = 0.0084 PO2 + 0.63. The slope of this r egression line is significantly steeper than the reported slopes of th e regression lines for human and dog erythrocytes measured under the s ame conditions. Our results revealed that calculation of Qc in pigs by using Theta(CO) values for human or dog erythrocytes would result in an underestimation of 51 and 50%, respectively.