Plasma hemoglobin distribution

After injection into mice, mercuric chloride has been found to be distributed equally between erythrocytes and plasma in blood for up to 1 day after the administration [12, 13]. There is, however, a gradual increase in red blood cell/plasma ratio. In the erythrocytes, mercury is probably bound to sulphydryl groups on the hemoglobin molecule [14], though the binding is readily reversible [15]. There is possibly also a binding to glutathione [16]. 

The equilibrium between plasma and red cells has been disturbed by the reactions described so far. The concentration of HCO3 has increased relatively more in the erythrocytes than in the plasma the pH of plasma has fallen relatively more than the pH of the erythrocytes and the non-difftisible ion concentration in the erythrocytes has fallen because of the increase in protonation of proteins and hemoglobin. The membrane potential of the erythrocytes therefore becomes less negative, and the distribution of all diffusible ions must change in accordance with the new membrane potential. The ion shifts that occur rapidly are a movement of HCO3 out of the erythrocytes and a movement of Cr into the erythrocytes to provide electrochemical balance. This shift of chloride ions is referred to as the chloride shift (Figure 46-9, reactions 6 and 7). As a result of these ion fluxes, the concentration of chloride in the venous plasma is about 1 mmol/L lower than that in the arterial plasma. 

Figure 1. Block diagram of a model for the control of erythropoiesis (HbO), oxyhemoglobin concentration Vi, viscosity factor (HbO), effective oxyhemoglobin concentration R, rate of erythropoietin release (E), plasma erythropoietin concentration E0, normal plasma erythropoietin concentration V , distribution volume for erythropoietin P, rate of hemoglobin production MT, erythrocyte maturation time L, rate of hemoglobin loss TH, total circulating hemoglobin (Hb), blood hemoglobin concentration Vb, blood volume Vp, plasma volume Vp0, normal plasma volume Vpf, steady-state hypoxic plasma volume MCV, mean corpuscular volume MCH, mean corpuscular hemoglobin k, constant...

Plasma protein concentrations are dynamic parameters that depend on the biosynthesis, distribution between intravascular and extravascular fluid compartments, and elimination (degradation, catabolism, and loss) of the proteins. Table 8.3 lists some of the common causes for changes of plasma protein and albumin concentrations. A rise in plasma albumin is often due to dehydration, and this can be confirmed by associated increases of plasma globulins, blood hemoglobin, and hematocrit (packed cell volume). 

Sodium nitroprusside can bind to vitamin B12 interfering with its distribution and metabolism, and it should be used with caution in patients having low plasma vitamin B12 concentrations. Excess cyanide also can bind to hemoglobin, producing methemoglobinemia. 

The carrier in the blood cells is hemoglobin (Clarkson et al., 1961) and possibly glutathione (Nielsen Kudsk, 1969). In the plasma, binding occurs to globulin and albumin and the distribution between different... 

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