Cerebral blood flow during hypoxic hypoxia with plasma-based hemoglobin at reduced hematocrit.

We determined whether cerebral blood flow (CBF) remained related to arterial O2 content (CaO2) during hypoxic hypoxia when hematocrit and hemoglobin concentration were independently varied with cell-free, tetramerically stabilized hemoglobin transfusion. Three groups of pentobarbital sodium-anesthetized cats were studied with graded reductions in arterial O2 saturation to 50%: 1) a control group with a hematocrit of 31 +/- 1% (mean +/- SE; n = 7); 2) an anemia group with a hematocrit of 21 +/- 1% that underwent an isovolumic exchange transfusion with an albumin solution (n = 8); and 3) a group transfused with an intramolecularly cross-linked hemoglobin solution to decrease hematocrit to 21 +/- 1% (n = 10). Total arterial hemoglobin concentration (g/dl) after hemoglobin transfusion (8.8 +/- 0.2) was intermediate between that of the control (10.3 +/- 0.3) and albumin (7.2 +/- 0.4) groups. Forebrain CBF increased after albumin and hemoglobin transfusion at normoxic O2 tensions to levels attained at equivalent reductions in CaO2 in the control group during graded hypoxia. Over a wide range of arterial O2 saturation and sagittal sinus PO2, CBF remained greater in the albumin group. When CBF was plotted against CaO2 for all three groups, a single relationship was formed. Cerebral O2 transport, O2 consumption, and fractional O2 extraction were constant during hypoxia and equivalent among groups. We conclude that CBF remains related to CaO2 during hypoxemia when hematocrit is reduced with and without proportional reductions in O2-carrying capacity. Thus O2 transport to the brain is well regulated at a constant level independently of alterations in hematocrit, hemoglobin concentration, and O2 saturation.

[1]  S. Ashwal,et al.  Developmental Changes in Thickness, Contractility, and Hypoxic Sensitivity of Newborn Lamb Cerebral Arteries , 1987, Pediatric Research.

[2]  M A Williams,et al.  Cerebral O2 transport with hematocrit reduced by cross-linked hemoglobin transfusion. , 1996, The American journal of physiology.

[3]  D. Becker,et al.  Mannitol causes compensatory cerebral vasoconstriction and vasodilation in response to blood viscosity changes. , 1983, Journal of neurosurgery.

[4]  J. H. Collins,et al.  Positive and negative cooperativities at subsequent steps of oxygenation regulate the allosteric behavior of multistate sebacylhemoglobin. , 1996, Biochemistry.

[5]  S. Chien,et al.  Effects of hematocrit variations on regional hemodynamics and oxygen transport in the dog. , 1980, The American journal of physiology.

[6]  S. Zeger,et al.  Hemodilution causes size-dependent constriction of pial arterioles in the cat. , 1989, The American journal of physiology.

[7]  R. Koehler,et al.  Influence of reduced oxyhemoglobin affinity on cerebrovascular response to hypoxic hypoxia. , 1986, The American journal of physiology.

[8]  S Zeger,et al.  Comparison of Cerebrovascular Response to Hypoxic and Carbon Monoxide Hypoxia in Newborn and Adult Sheep , 1984, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[9]  S. Ashwal,et al.  Direct effects of graded hypoxia on intact and denuded rabbit cranial arteries. , 1989, The American journal of physiology.

[10]  J. Olesen,et al.  Influence of carbon monoxide and of hemodilution on cerebral blood flow and blood gases in man. , 1973, Journal of applied physiology.

[11]  S. Rebello,et al.  Effect of diaspirin crosslinked and stroma-reduced hemoglobin on mean arterial pressure and endothelin-1 concentration in rats. , 1995, Life sciences.

[12]  B. Siesjö,et al.  The influence of acute normovolemic anemia on cerebral blood flow and oxygen consumption of anesthetized rats. , 1975, Acta physiologica Scandinavica.

[13]  R. Koehler,et al.  Base-line O2 extraction influences cerebral blood flow response to hematocrit. , 1988, The American journal of physiology.

[14]  H. Tenjin,et al.  Effect of Hemodilution on Cerebral Hemodynamics and Oxygen Metabolism , 1992, Stroke.

[15]  J. Ulatowski,et al.  Regional blood flow alterations after bovine fumaryl beta beta-crosslinked hemoglobin transfusion and nitric oxide synthase inhibition. , 1996, Critical care medicine.

[16]  M. Boegehold,et al.  Nitric oxide modulates arteriolar responses to increased sympathetic nerve activity. , 1996, The American journal of physiology.

[17]  J. Weeks,et al.  Cerebral blood flow, blood volume, and brain tissue hematocrit during isovolemic hemodilution with hetastarch in rats. , 1992, The American journal of physiology.

[18]  O. Paulson,et al.  Increased Cerebral Blood Flow in Anemic Patients on Long-Term Hemodialytic Treatment , 1992, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[19]  A. Heyman,et al.  Cerebral circulation and metabolism in sickle cell and other chronic anemias, with observations on the effects of oxygen inhalation. , 1952, The Journal of clinical investigation.

[20]  渡邉 学 Intravital microreflectometry of individual pial vessels and capillary region of rat , 1993 .

[21]  J. Krasney,et al.  Cerebral pressure-flow and metabolic responses to sustained hypoxia: effect of CO2. , 1994, Journal of applied physiology.

[22]  R. Lees The Effects of Extreme Hemodilutions on the Autoregulation of Cerebral Blood Flow , Electroencephalogram and Cerebral Metabolic Rate of Oxygen in the Dog , 2022 .

[23]  H. Saito,et al.  NG-methyl-L-arginine, an inhibitor of L-arginine-derived nitric oxide synthesis, stimulates renal sympathetic nerve activity in vivo. A role for nitric oxide in the central regulation of sympathetic tone? , 1992, Circulation research.

[24]  R J Traystman,et al.  Regional blood flow and O2 transport during hypoxic and CO hypoxia in neonatal and adult sheep. , 1985, The American journal of physiology.

[25]  R. Koehler,et al.  Role of O2-hemoglobin affinity on cerebrovascular response to carbon monoxide hypoxia. , 1983, The American journal of physiology.

[26]  R. Koehler,et al.  Effect of hematocrit on cerebral blood flow. , 1986, The American journal of physiology.

[27]  B. Hindman,et al.  Cerebral blood flow and oxygen delivery during hypoxemia and hemodilution: role of arterial oxygen content. , 1994, The American journal of physiology.

[28]  J. Ulatowski,et al.  Production and characteristics of an infusible oxygen-carrying fluid based on hemoglobin intramolecularly cross-linked with sebacic acid. , 1996, The Journal of laboratory and clinical medicine.

[29]  R. Traystman,et al.  Effects of changes in arterial O2 content on cerebral blood flow in the lamb. , 1981, The American journal of physiology.

[30]  A. Shoukas,et al.  Pial microvascular hemodynamics in anemia. , 1993, The American journal of physiology.

[31]  G. Bouma,et al.  Effect of hematocrit variations on cerebral blood flow and basilar artery diameter in vivo. , 1992, The American journal of physiology.

[32]  H. Granger,et al.  Effect of Changing Metabolic Rate on Local Blood Flow Control in the Canine Hindlimb , 1978, Circulation research.

[33]  K. Burhop,et al.  A role for endothelin and nitric oxide in the pressor response to diaspirin cross-linked hemoglobin. , 1993, The Journal of laboratory and clinical medicine.

[34]  J. Wade,et al.  Fundamental importance of arterial oxygen content in the regulation of cerebral blood flow in man. , 1985, Brain : a journal of neurology.

[35]  D. Heistad,et al.  Humoral Regulation of Blood Flow to Choroid Plexus: Role of Arginine Vasopressin , 1988, Circulation research.

[36]  D. Heistad,et al.  Effects of angiotensin II on blood flow to choroid plexus. , 1990, The American journal of physiology.

[37]  M. C. Rogers,et al.  Cerebrovascular hypoxic and autoregulatory responses during reduced brain metabolism. , 1985, The American journal of physiology.

[38]  D. Heistad,et al.  Effect of endogenous vasopressin on blood flow to choroid plexus during hypoxia and intracranial hypertension. , 1994, The American journal of physiology.

[39]  Govind Singh,et al.  Role of endothelin in the cardiovascular effects of diaspirin crosslinked and stroma reduced hemoglobin. , 1996, Critical care medicine.