Effects of RBC deformability and artificial blood on hypoxic pulmonary vasoconstriction

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 09671562
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Anesthesiology/Resuscitation studies
• Research Institution: Tottori University
• Principal Investigator: OSHIMA Yoshiaki Tottori University, Faculty of Medicine, Department of Anesthesiology, Research Associate, 医学部, 助手 (90233105)
• Project Period (FY): 1997 – 1998
• Keywords: hypoxic pulmonary vasoconstriction / isolated perfused lung / electric circuit model / hematocrit / isoflurane / nitric oxide / phosphoenolpyruvate / artificial red blood cells

Research Abstract

Objectives: We examined the participation of red blood cells in the hypoxic pulmonary vasoconstriction(HPV). Methods: Pump-perfused rabbit lungs were reperfused and ventilated with a mixture of 21% 0ィイD22ィエD2, 5% C0ィイD22ィエD2, and balance NィイD22ィエD2. HPV was induced by reduction of 0ィイD22ィエD2 concentration from 21 to 3% for 5 min. Pulmonary arterial pressure(PAP) and flow velocity wave patterns were measured using a low-pressure transducer and an electromagnetic flow meter, respectively, and impedance wave patterns were determined after fast Fourier transformation. When the impedance wave patterns were approximated by an electric circuit model using least squares method, the resistance in the proximal and peripheral regions(R1, R2), the inductance in both regions (Li, L2), and the capacitance in both regions(C1, C2) were calculated. Two perfusion solutions, 1) a mixture of autologous red blood cells and physiological salt solution with supplemented 5% albumin and 2) that of artificial r ed blood cells(liposome-encapsulated hemoglobin) and physiological saline supplemented with 5% albumin, were made. Using each solution, HPV was evaluated by the above-written parameters with and without inhalation of nitric oxide(NO). Results: 1. With both autologous and artificial perfusion solutions, hypoxic stimulation(HS) increased PAP, Ri & R2, and Li & L2, and decreased Ci & C2. 2. With the autologous solution, a rise of hematocrit enhanced the H S-induced PAP increase and changes of the parameters mentioned above. 3. With the autologous solution, NO inhalation suppressed the HS-induced PAP increase and changes of the parameters mentioned above, but with the artificial solutions no such a phenomenon was observed.
Conclusions: 1. The enhancement of the HS-induced PAP increase by a rise of hematocrit was based on the changes of all the following factors, I. E., Ri & R2, Li & L2, and Ci & C2. 2. NO inhalation failed to suppress HPV with the artificial solution, probably since the liposome-encapsulated hemoglobin strongly inactivated NO.