Oxygen metabolic depression effect

A number of studies have summarized potential impacts to different types of organisms, including adult fish, developmental fish, zooplankton, and benthic fauna. While earlier studies focused mainly on lethal impacts to coastal fauna exposed to strong acids, recent data have focused on deep-water organisms exposed to CO2, and have included sub-lethal effects. Impacts include respiratory stress (reduced pH limits oxygen binding and transport of respiratory proteins), acidosis (reduced pH disrupts an organism s acid/basis balance), and metabolic depression (elevated CO2 causes some animals to reach a state of torpor). 

Another candidate mediator of hypoxic metabolic depression is cytochrome oxidase, the final oxygen acceptor in the mitochondrial electron transfer chain, whose own oxygen-sensing capabilities are the subject of much speculation. Work must continue to investigate the effects of the chronic hypoxia of the fetus on the function of cytochrome oxidase and its implications for cerebral and peripheral metabolism during pregnancy. 

By means of the video tracking system it was possible to observe the behavioural response of tilapia O. mossambicus) during severe hypoxia [58]. The authors found no differences to the normoxic state so that the calorimetrically determined 50 % reduction of the heat production rate had to be ascribed to a lowered cellular energy metabolism which is known as metabolic depression. Moreover, strong fluctuations between aerobic and anaerobic periods were observed in the power-time curves. A slow acidification of the water had no influence on heat production, oxygen consumption and oxycaloric equivalent of tilapia under normoxic conditions. And even an additional stepwise hypoxia showed no potentiating effect [136,151]. 

Mecfianism of Action A cinchona alkaloid that relaxes skeletal muscle by increasing the refractory period, decreasing excitability of motor end plates (curare-like), and affecting distribution of calcium with muscle fiber. Antimalaria Depresses oxygen uptake, carbohydrate metabolism, elevates pH in intracellular organelles of parasites. Therapeutic Effect Relaxes skeletal muscle produces parasite death. Pharmacokinetics Rapidly absorbed mainly from upper small intestine. Protein binding 70%-95%. Metabolized in liver. Excreted in feces, saliva, and urine. Half-life 8-14 hr (adults), 6-12 hr (children). 

The toxic action of bilirubin on tissue metabolism has been demonstrated both by in vitro and in vivo experiments. Lathe (LI) added bilirubin to brain brei, in concentrations such as occur in hemolytic disease of the newborn and prematurity, and observed a decrease in oxygen consumption. Day (D3) was able to reverse this depressed respiration by the addition of cytochrome c or methylene blue. Bowen and Waters (B16) then showed that this reversal could also be efFected by diphosphopyridine nucleotide. Zetterstrom and Ernster (Zl), using isolated rat liver mitochondria, showed that bilirubin in concentrations... 

Copper and Zinc in Aerobic Metabolism. Cytochrome oxidase, the terminal oxidase in the electron transport chain contains an atom of copper. On this enzyme the protons and electrons generated during oxidative metabolism combine with elemental oxygen to form water. During copper deficiency the tissue concentration of cytochrome oxidase is reduced. While the effects of lower cytochrome oxidase activity on exercise has not been described, it is likely that aerobic energy metabolism will be diminished. This effect of copper deficiency was first described in animals with myelin aplasls — the degeneration myelin (86). The oxidative process of phospholipid synthesis, a primary component of myelin, was depressed. Liver mitochondria had impaired respiratory activity (87). Cytochrome oxidase activity was also depressed in brain, heart and liver. 

Barbiturates depress neuronal activity in the CNS. This is accompanied by decreased cerebral metabolic oxygen consumption and decreased cerebral blood flow, since the coupling of blood flow to brain metabolism is preserved with the barbiturates. It also results in a decrease in ICP. Barbiturates depress neuronal activity in the cerebral cortex, thalamus and motor centers. Barbiturates are effective anticonvulsants (see Ch. 9), reduce intraocular pressure, increase the threshold of spinal reflexes and provide excellent muscle relaxation. The barbiturates lack specific analgesic effects and are, therefore, not suitable as the sole anesthetic for invasive procedures. 

A 6 month inhalation study was conducted in rats in which the animals were exposed daily to 10 mg m At 3 months, neuromuscular depression, lymphopenia, neutrophilia, and decreased oxygen consumption were observed. In the fifth month, increased organic sulfate elimination, variation in weight, arterial pressure, liver function, and protein metabolism were observed. Liver damage was reported upon histological examination. Studies on the teratogenic, embryotoxic, and cytogenic effects of 2-ME have been inconclusive. 

Quinine, a cinchona alkaloid, acts primarily as a blood schizonticide. Qninine s antimalarial action is unclear. It was once believed to be dne to the intercalation of the qninoline moiety into the DNA of the parasite, thereby reducing the effectiveness of DNA to act as a template, as well as depression of the oxygen uptake and carbohydrate metabolism of the plasmodia. Recently it has been thonght that quinine s pH elevation in the intracellular organelles of the parasites plays a role in the mechanism. 

The diagnosis of subdural hematoma explains the depressed respirations, which have resulted in carbon dioxide retention and respiratory acidosis. The metabolic system is beginning to buffer the respiratory acids with retention of bicarbonate. The nurse would watch the oxygen levels and respiratory rate closely and continue supplemental oxygen therapy to maintain adequate oxygenation and would prepare to artificially ventilate Ms. Suarez to improve CO removal and total ventilatory effectiveness. 

GI Tract May cause gastrointestinal irritation with nausea, vomiting, and diarrhea. May cause effects similar to those for inhalation exposure. Systemic Effects May cause central nervous system depression. Metabolism may release cyanide, which may result in headache, dizziness, weakness, collapse, unconsciousness, and possible death. May be metabolized to cyanide, which in turn acts by inhibiting cytochrome oxidase, impairing cellular respiration. May cause tissue anoxia, characterized by weakness, headache, dizziness, confusion, cyanosis (bluish discoloration of skin due to deficient oxygenation of the blood), weak and irregular heart beat, collapse, unconsciousness, convulsions, coma, and death. 

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