Consequences of an acute increase in P 50 in anaesthetized guinea pigs

• Published in: Respiration physiology Vol. 51; no. 1; pp. 21 - 30
• Main Authors: Soulard, Claude D., Teisseire, Bernard P., Teisseire, Liliane J., Herigault, Robert A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1983
• Subjects: Cardiac output; Erythrocyte; Oxygen consumption; P 50; Peripheral circulation; Tissue blood flow; Erythrocyte; Peripheral circulation; Tissue blood flow; Oxygen consumption; Cardiac output; P 50
• ISSN: 0034-5687
• DOI: 10.1016/0034-5687(83)90099-3

In anaesthetizes guinea pigs, ventilated with ambient air, the peripheral haemodynamics and oxygen transport characteristics have been studied following a blood exchange transfusion with rat erytrocytes suspended in guinea pig plasma. Since the rat haemoglobin exhibited a lower oxygen affinity than guinea pig haemoglobin, the oxygen partial pressure at 50% of oxygen haemoglobin saturation (PsO) increased from 25.2 ± 1.1 to 37.2 ± 0.9mm Hg (n= 10). This increase in PsO was accompanied by a significant increase in arterial oxygen partial pressure (Pao2) and in arterio-venous difference (AVDo2). Cardiac output (Q) was decreased significantly, but oxygen consumption (~'o2) remained within control values. The increase in PsO was associated with a venous oxygen partial pressure (1~o2) which remained constant but an increase in blood lactate concentration was observed. Control exchange transfusion with fresh guinea pig blood had no effect on acid-base status, on oxygen transport, or on peripheral resistance. The sudden reduction in haemoglobin oxygen affinity induced an increase in peripheral resistance with a decrease in cardiac output, the arterial systemic pressure being maintained. These results suggested that an acute decrease in haemoglobin oxygen affinity was compensated for by a simultaneous diminution of overall tissue blood flow and reduction of capillary recruitment.