Reactions in muscle

A combination of the novel flash photolysis technique enabling the rapid release of nucleotides such as ATP from inert, photolabile precursors (Kaplan et al., 1978 McCray et al., 1980 Gurney Lester, 1987) with the high x-ray intensities available from synchrotron sources has introduced the possibility of studying the kinetics of structural events associated with the actomyosin ATPase reactions in muscle fibres. The precursor or caged nucleotides can readily diffuse into skinned muscle fibres, where, in the case of caged-ATP, a pulse of ultraviolet (u.v.) light will photolyse... 

Potassium, as K+, is an essential element for both humans and other animals that plays an important role in metabolic processes, especially in its ability to accelerate chemical reactions in muscles and provide muscles with their energy. Potassium and sodium together... 

While the concentrations of ATP, ADP, and the phosphate ion are neither constant nor known exactly, it is possible to make an estimate of the Gibbs energy released on the ATP hydrolysis reaction in muscles at body temperature (37°C) as in the illustration below. 

Lactate dehydrogenase Catalyzes reactions in muscle and liver cells... 

In general, the thyroid hormone increases glucose level by glycogenolysis and gluconeogenesis, stimulates lipolysis especially in hyperthyroidism. In normal conditions, the thyroid hormone has stimulatory effects on the synthesis of proteins but also leads to catabolic reactions in muscle under hypo- and hyperthyroid states [10]. 

Theoretically, spontaneous reactions can be used to obtain useful work. By useful work, we mean energy that can be used directly to move objects of normal size. We use the combustion of gasoline to move an automobile, and we use a reaction in a battery to generate electricity to drive a motor. Similarly, biochemical reactions in muscle tissue occur in such a way as to contract muscle fibers and lift a weight. 

Drews GA, Engel WK. (1966) Reversal of the ATPase reaction in muscle fiber by BDTA. Nature 212, 1551-1553. 

UTP into RNA was actually somewhat less in reaction mixtures primed with chromatin prepared from rats that had received growth hormone than in those primed with chromatin from control rats. Thus, Breuer and Florini concluded (13) that growth hormone does not act on the polymerase reaction in muscle by increasing the template activity of DNA, but perhaps it affects the enzyme directly either by altering its activity or by increasing the amount of enzyme present in the nucleus. 

First, all the individual stages which constitute the cycle have been demonstrated to occur in muscle tissue, and the rates at which the individual reactions can proceed are sufficient to account for the maximum rate of respiration. The occurrence of some of the reactions in muscle tissue, as already mentioned, has been known since 1911, when Batelli and Stern demonstrated the rapid oxidation of citrate, succinate, fuma-rate, and malate in frog muscle. In 1936 the work of Martiusand Knoop - revealed the mechanism of the conversion of citrate into succinate, and the last major step of the cycle was discovered in 1937, when the formation of citrate from oxalacetate and pyruvate was demonstrated. It was this reaction which made a series of reactions into a cyclic sequence and which linked the series of reactions leading from citrate to oxalacetate with carbohydrate metabolism. 

Description of Method. Creatine is an organic acid found in muscle tissue that supplies energy for muscle contractions. One of its metabolic products is creatinine, which is excreted in urine. Because the concentration of creatinine in urine and serum is an important indication of renal function, rapid methods for its analysis are clinically important. In this method the rate of reaction between creatinine and picrate in an alkaline medium is used to determine the concentration of creatinine in urine. Under the conditions of the analysis, the reaction is first-order in picrate, creatinine, and hydroxide. 

ATP stores in muscle are augmented or supplemented by stores of phosphocreatine. During periods of contraction, phosphocre-atine is hydrolyzed to drive the synthesis of needed ATP in the creatine kinase reaction ... 

FIGURE 19.24 A mechanism for the phosphoglycerate mutase reaction in rabbit muscle and in yeast. Zelda Rose of the Institute for Cancer Research in Philadelphia showed that the enzyme requires a small amount of 2,3-BPG to phosphorylate the histidine residue before the mechanism can proceed. Prior to her work, the role of the phosphohistidine in this mechanism was not understood. 

In the kidney and in muscle tissues, fructose is readily phosphorylated by hexokinase, which, as pointed out above, can utilize several different hexose substrates. The free energy of hydrolysis of ATP drives the reaction forward ... 

The lactic acid (C3H603(flg), AG = —559 kj) produced in muscle cells by vigorous exercise eventually is absorbed into the bloodstream, where it is metabolized back to glucose (AG = —919 kj) in the liver. The reaction is... 

The natural polymers known as proteins make up about 15% by mass of our bodies. They serve many functions. Fibrous proteins are the main components of hair, muscle, and skin. Other proteins found in body fluids transport oxygen, fats, and other substances needed for metabolism. Still others, such as insulin and vasopressin, are hormones. Enzymes, which catalyze reactions in the body, are chiefly protein. 

By using direct mechanical action from the artificial muscle, it would be possible to produce reliable sensing and control devices without electrical and electronic equipment. Another interesting application would be to drive prosthetic devices where the action would be similar to the muscle reaction in the body. This unusual type of chemically induced motion should be an interesting one to explore for the solution of unusual problems where conventional approaches do not work. 

If the patient experiences dizziness or drowsiness, it is important to provide assistance with ambulation. If drowsiness is severe or if other problems such as dizziness or a disturbance in muscle coordination occur, the patient may require assistance with ambulation and other activities. The nurse places the call light within easy reach and instructs the patient to call before attempting to get out of bed or ambulate. The nurse informs the patient that this adverse reaction may lessen with continued use of the drug. 

Although the fundamental chemomechanical transduction processes seem to be the same in all types of vertebrate muscle, contraction in smooth muscle is characterized by much greater involvement of enzymatically catalyzed control reactions. In smooth muscle the control reactions themselves involve the use of phosphorylation-dephosphorylation cycles. Moreover, they are futile in the sense they cause the expenditure of bond energy without a tangible work resultant, i.e., compounds synthesized or external work done. 

The most common unwanted effects of the barbiturates are oversedation and psychomotot impaitment, which may petsist well into the next day following a hypnotic dose. Patadoxical excitement, hypersensitivity reactions, and muscle or joint pain may occur in rare cases. Drug-drug interactions occur with the CNS sedatives, and a number of drugs have enhanced metabolism when co-administered with barbiturates (Barnhill et al. 1989). 

Moneret-Vautrin DA Cross-reactions to muscle relaxants in the operating room. Clin Rev Allergy Immunol 1997 15 471. 

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