Blood bicarbonate

The signs and symptoms of diabetes consist of thirst, anorexia, nausea, vomiting, abdominal pain, headache, drowsiness, weakness, coma, severe acidosis, air hunger (Kussmaul s breathing), sweetish odor of the breath, hyperglycemia, decreased blood bicarbonate level, decreased blood pH, and plasma that is strongly positive for ketone bodies. 

A newborn male infant failed to thrive and develop normally immediately after birth. His most remarkable laboratory results were arterial pH 7.30, blood bicarbonate 16 meq/L, lactate 5 mM (normal less than 2.5), and an anion gap of 27 meq/L. By the age of 16 weeks,... 

Based on the presence of at least three of the following findings generalized aminoaciduria, glucosuria, increased Fepo4j decreased blood bicarbonate concentration. 

Lipids form a minor part of the carbon content of herbivore diets As a result, despite the fact that they are used primarily for energy metabolism, their abundance is not sufficient to greatly influence the isotopic composition of blood bicarbonate For this reason, the isotopic composition of lipids will not significantly affect the isotopic ratio of carbon in bone apatite ... 

A theoretical model for carbon isotope fractionation between herbivore diets and herbivore bone is shown in Figure 2A This model shows the isotopic relationship of gelatin to that of hydroxyapatite and the relationship of both to the original plant food diet The gelatin seems to reflect the growth portion of the diet while the apatite seems to reflect the energy portion of the diet The difference of - 1 o/oo between apatite values and gelatin values is due in part to the fact that blood bicarbonate has a enrichment produced by the transfer of CO from blood plasma to expired air This effect has been experimentally verified and will be described elsewhere ... 

The actual results of isotopic analyses of herbivore bone from animals with a variety of diets are shown in Figure 2B The line represents a direct relationship between isotopic composition of gelatin and that of apatite with an offset of -t o/oo due to the blood bicarbonate effect mentioned above The results in Figure 2B are all from contemporary herbivores and fit the model closely Ancient herbivore bones give similar results ( Thus we can use either carbon isotopes in gelatin or carbon isotopes in apatite to determine dietary intake in herbivores For very old bones collagen is usually decomposed (15) and only the apatite results can be obtained ... 

Carbohydrates are almost negligible in pure carnivore diets, the only significant source being glycogen stored in the cells of the meat eaten It is unlikely that this glycogen is sufficient in quantity to significantly affect the isotopic composition of blood bicarbonate or bone apatite ... 

The normal value of blood bicarbonate is about 26 meq/L (25 to 32 meq/L), or 0.026 meq/mL. Meq HCOa" = mmol HCOs". Since 0.1 mL blood was taken for analysis, it should consume about 0.0026 mmol HCl, or 0.26 mL of 0.01 MHCl. Hence, since 1 mL of 0.01 M HCl was taken, about 0.74 mL should remain unreacted, and the back-titration should take about 0.7 mL of... 

It would be difficult to deliver a pH buffer to muscle cells in vivo under normal conditions bnt an indirect way involves ingesting sodium bicarbonate. This has been trialed with some success. By increasing the pH-bnffering capacity of the blood, bicarbonate has been shown to reduce the time to run 400 m by 1-2 s. However, this procedure is dangerous because an overdose of bicarbonate can cause respiratory alkalosis that gives rise to a reduced oxygen supply to the brain. 

Effector organs are mainly the respiratory muscles, as described previously. Other effectors are muscles located in the airways and tissues for mucus secretion. Control of respiration appears to be based on two criteria (1) removal of excess CO2 and (2) minimization of energy expenditure. It is not the lack of oxygen that stimulates respiration but increased CO2 partial pressure that acts as a powerful respiratory stimulus. Because of the buffering action of blood bicarbonate, blood pH usually falls as more CO2 is produced in the working muscles. Lower blood pH also stimulates respiration. 

For the present, some aspects of the composition of the pancreatic juices and regulation of their secretion will be considered. Pancreatic juice is alkaline and contains zymogens. The alkalinity (pH 7-8) results from the excretion of blood bicarbonate (HCO3) against a concentration gradient. Thus, the intravenous administration of radioactive bicarbonate is rapidly followed by concentration of the radioactivity in the pancreatic juice. 

In such a case, the first stage is uncompensated metabolic acidosis, in which excess H is largely taken up by the blood buffers. The chemical reactions are shown in Table 3.5. Both types of buffer base, bicarbonate and non-bicarbonate, combine with hydrogen ions. For the bicarbonate system, the CO2 yielded (reaction 2) is lost via the lungs. As a result of reaction 2 in Table 3.5, bicarbonate is removed from the blood to be excreted as COj and the blood bicarbonate concentration falls. 

A method of expressing whole blood bicarbonate. It can be calculated from the Henderson-Hasselbalch equation ... 

The secretion of hydrochloric acid by the stomach is accompanied by an increase in blood bicarbonate and pH. 

A disorder characterized by an abnormally high level of acid in the blood, or by a decrease in the blood bicarbonate. The excess acids may consist of ketone bodies, phosphoric acid, sulfuric acid, hydrochloric acid, lactic acid, or carbonic acid. 

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