Blood buffer components

Probably the most effective use of XRF and TXRF continues to be in the analysis of samples of biological origin. For instance, TXRF has been used without a significant amount of sample preparation to determine the metal cofactors in enzyme complexes [86]. The protein content in a number of enzymes has been deduced through a TXRF of the sulfur content of the component methionine and cysteine [87]. It was found that for enzymes with low molecular weights and minor amounts of buffer components that a reliable determination of sulfur was possible. In other works, TXRF was used to determine trace elements in serum and homogenized brain samples [88], selenium and other trace elements in serum and urine [89], lead in whole human blood [90], and the Zn/Cu ratio in serum as a means to aid cancer diagnosis [91]. 

Biological fluids, including the cytosol and extracellular fluids such as blood, are buffered. For example, in healthy individuals the pH of the blood is carefully controlled at pH 7.4. The major buffering components in most biological fluids... 

Bile is formed and secreted continuously by polygonally shaped liver parenchymal cells called hepatocytes. An aqueous buffer component (e.g., HCOj") is added to the bile by the hepatic bile duct cells that carry the secretion toward the common bile duct. The membrane of the hepatocytes in contact with the blood has microvilli that facilitate the exchange of substances between plasma and the cells. Hepatocytes are rich in mitochondria and endoplasmic reticulum. Hepatic bile flows into the gallbladder, where it is concentrated, stored, and emptied into the duodenum when the partially digested contents of the stomach enter... 

Oxoanions of phosphorus are buffer components in blood. For a KH2P04-Na2HP04 solution with pH = 7.40 (pH of normal arterial blood), what is the buffer-component concentration ratio ... 

State that a change in standard bicarbonate is indicative of a metabolic component in an acid-base disorder. Explain this on the graph of the blood buffer line and explain why the magnitude of the change in standard bicarbonate is an underestimate of the magnitude of the metabolic disorders. 

As we discussed in the opening section of this chapter, blood contains several buffering systems, the most important of which consists of carbonic acid and the carbonate ion. The concentrations of these buffer components in normal blood plasma are [HC03 ] = 0.024 M and [H2CO3] = 0.0012 M. The p fj, for carbonic acid at body temperature is 6.1. If we substitute these quantities into the Henderson-Hasselbalch equation, we can calculate the normal pH of blood ... 

This isotonic volume expander contains sodium, potassium, chloride, and lactate that approximates the fluid and electrolyte composition of the blood. Ringer s lactate (also known as lactated Ringer s or LR) provides ECF replacement and is most often used in the perioperative setting, and for patients with lower GI fluid losses, burns, or dehydration. The lactate component of LR works as a buffer to increase the pH. Large volumes of LR may cause metabolic alkalosis. Because patients with significant liver disease are unable to metabolize lactate sufficiently, Ringer s lactate administration in this population may lead to accumulation of lactate with iatrogenic lactic acidosis. The lactate is not metabolized to bicarbonate in the presence of liver disease and lactic acid can result. 

The carbonic acid-bicarbonate buffer system has a of 6.1, yet is still a very effective buffer at pH 7-4 because it is an open buffer system, in which one component, CO2, can equilibrate between blood and air. 

The human body is a remarkable machine. It relies on a variety of safeguards to keep blood pH constant. Our blood constitutes a buffer system — meaning, it has components that can react with excess base or excess acid. Carbon dioxide, which is produced by the metabolism of food, dissolves in blood to produce carbonic acid, and carbonic acid can neutralize any excess base. The bicarbonate ion, also present in blood, will promptly take care of any surplus acid. The level of carbon dioxide in the blood adjusts to a body s rate of respiration. If blood pH drops — which actually means that the blood has... 

In the isolated perfused liver experiments, buffers containing no erythrocytes or serum proteins are used to examine the direct interaction of a gene drag with tissues and to avoid the interaction of a gene drag with blood components and possible contamination of nucleases. 

No studies on body burden reduction methods were located. The state of definitive knowledge of white phosphorus metabolism is too limited to permit extensive speculation on methods for reducing body burden. However, it is possible that increasing selective excretion of phosphate may increase the rate of inorganic conversion of white phosphorus to phosphate (this conversion is described in detail in Section 2.3). Since phosphate is a naturally occurring component of the blood s buffering system, this would effectively deactivate the phosphorus. No methods for selectively increasing phosphate excretion were located. 

But what if we had a buffer solution containing acetic acid and sodium acetate, each at 0.10 M The previous example shows us the pH of this buffer is equal to the pKa. If we dilute 1.0 L of this buffer to a new volume of 10.0 L, the concentration of each component falls to 0.010 M. However, the ratio of the two components remains the same, so the pH remains at 4.74. Since blood is a buffered solution, you can administer several liters of normal saline without changing the pH of blood. 

An important factor in the interaction of foreign surfaces with blood is the rapid adsorption of plasma proteins onto such surfaces when they are exposed to blood (4). For this reason the adsorption of radioactively tagged blood components on heparinized and unheparinized surfaces was measured. Proteins were dissolved in approximate physiological concentrations in a buffered (pH 7.35) physiological saline solution and the solutions were exposed to the test surfaces for 2 hours at 37 °C. in a static system. After the exposure, the surfaces were rinsed with physiological saline and distilled water and then dried. The amount of protein on the surfaces was determined in a 27r-gas flow proportional counter (7). As shown in Table III, although both heparinized surfaces were nonthrombogenic, there is no consistent pattern of either increased or decreased adsorption of the proteins caused by the heparinization. In-... 

Nakamura et al. [42] developed a simple and rapid semi-micro colunm HPLC method with UV detection for the simultaneous determination of lornoxicam and other oxicams in human blood samples. The drugs including isoxicam as an internal standard were extracted from buffered plasma samples (pH 3) with dichloromethane and the resulting extracts were subjected to HPLC analysis. The separation was performed with a Ci8 reversed-phase semi-micro column (25 cm x 1.5 mm, 5 pm) at 35 °C. The mobile phase used was a mixture of acetonitrile-0.1 M acetate buffer (pH 5)-methanol, and the detection wavelength was set at 365 nm. The drugs were separated within 30 min without interference by the blood components. The detection limits of lornoxicam were 6.4 ng/ml in serum and 9.3 ng/ml in plasma at a signal-to-noise ratio of 3. The method was applied to the determination of lornoxicam in the sera of the patients. 

Fig. 2 Fractograms were obtained with a Sd-FFF apparatus (77 X 1 X 0.0125 cm), (a) RBC elution profile on a new or properly washed FFF channel. Elution conditions flow injection of 5 X 10 RBCs (1/20 dilution of total blood in phosphate buffer saline pH 7.4/0.1 % of bovine albumin) external field 9.45g (1 g = 9.81 cm/s ) flow rate 0.7 mL/min, photometric detection at A = 313 nm. (b) Channel poisoning effect observed after 47 identical injections Idescribed in (A)], (c) Two sequences of RBC elution and channel cleaning procedure. Each sequence is RBC fractogram (flow injection of 5 X 10 RBCs (1/20 dilution of total blood in phosphate buffer saline pH 7.4), external field 25.7g, flow rate of 1.02 mL/min, photometric detection at A = 313 nm), external field stopped (S.R.), hypo-osmolar shock with doubly distilled water, cleaning agent (C.A.) signal, second water washing, (d) Example of fragile nucleated cells eluted in Sd-FFF neuroblasts (NB) case. Elution conditions flow injection of 1.5 X 10 neuroblasts in phosphate buffer saline pH 7.4/0.1 % of bovine albumin), external field 60.0g, flow rate of 1.25 mL/min, photometric detection at A = 254 nm. (e) Separation of components from an artificial mixture of neuroblasts and RBC. Elution conditions flow injection of 1.5 X 10 neuroblasts and 5 X 10 RBC in phosphate buffer saline pH 7.4/0.1 % of bovine albumin, external field 50.0g, flow rate of 1.25 mL/min, photometric detection at A = 254 nm.

In t ie case of animal plasma preparation, an anticoagulant is necessary to maintain solubility of blood components, and sodium citrate or lithium heparin would be preferable over any alternatives that contain EDTA. EDTA will chelate magnesium and zinc ions and require much higher concentrations of the two ions in the assay buffer for acceptable hnal ion concentrations, possibly to the point of precipitation. 

BICARBONATE BUFFER Bicarbonate buffer, one of the more important buffers in blood, has three components. The first of these, carbon dioxide, reacts with water to form carbonic acid ... 

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