Interrelations of Magnesium, Potassium, Phosphorus, and Creatine in Skeletal Muscle of Man 1

Abstract

In latter years the growth of methods has led to a detailed understanding of the concentration and distribution patterns of electrolytes and water in the extracellular liquids. More recently attention has been directed toward the intracellular phase. The greater bulk of observations has been concerned with the most abundant intracellular cation, potassium. Much less is known about magnesium, second only to potassium with respect to concentrations within cells.There are many indications of the intimate role which magnesium plays in modulating neural excitability and muscular contraction (1-7); in catalysing several enzymic processes concerned with the transfer, storage and utilization of energy (8)(9)(10)(11)(12)(13)(14) ; and, perhaps, in the adjustment of overall bodily economy reflected in temperature regulation and hibernation (15,16). Yet little is known of the patterns of its ebb and flow into and out of cells, or, indeed, of the concentrations obtaining within cells during most diseased states. This study was begun in order to discover what changes, if any, occurred in the magnesium content of skeletal muscle during certain clinical states marked by disturbances of electrolyte metabolism and accompanied occasionally by asthenia.For purposes of reference, concentrations of magnesium and of potassium in muscle were measured at the same time. It soon became apparent that even in the most diverse states of disease, as well as in health, an extraordinarily fixed relationship obtained in muscle between concentra-

The Effects of Resistance Exercises on the Nitrogen, Phosphorus, and Calcium Metabolism of Patients With Rheumatoid Arthritis 12

“…Nitrogen-phosphorus ratios, derived from these experimental data, were less than the ratio of 14.7 calculated for muscle protein from balance studies (4) and the ratio of 15.3 (0.065 gram of P per 1 gram of N) calculated from analysis of human, collagen-free muscle (10). It is apparent, howvever, that both nitrogen and phosphorus were retained and approximately in proportion to their content in muscle, and that under the conditions of these experiments, resistance exercises had a protein anabolic effect similar to testosterone (11).…”

The Measurement of Muscle Mass in Children Using [15N]Creatine

“…The concentration in muscle also shows individual variation (I). When the daily excretion of urinary creatinine is used to estimate muscle mass, it is important to recognize that both creatine turnover (13,35) and creatine content of muscle (1) vary in the individual in differing clinical states. Other workers have pointed out the unreliability of using a single constant to relate muscle mass to creatinine excretion (21).…”

“…changes in fat, water, and muscle in children who have recoveredcreatine pool (g) from severe protein-energy malnutrition. (1) creatine concentration in muscle (lg/mg wet weight of muscle) Skeletal muscle is the major component of lean body mass and is also the largest protein reservoir in the body. However, there is no accurate method for measuring muscle mass in man.…”

Studies on the Intracellular Water, Sodium and Potassium in Thyrotoxic Myopathy and in Thyrotoxic Periodic Paralysis

“…Sodium and potassium in human skeletal muscle tissue have been reported by many authors (Mudge and Vislocky, 1949;Baldwin et al, 1952;Mokotoff et al, 1952;Talso et al, 1953;Wilson, 1955;Barnes et al, 1957;Litchfield and Gaddie, 1958;Nichols, 1958;Flear and Crampton, 1960;Bergstrom, 1962) and the results showed some difference due to different method of ashing or preparation. Studies upon water and electrolytes metabolism in thyrotoxicosis have been done by several authors (Byrom 1934;Boekelman, 1948;Cachera et al, 1949;Munro et al, 1958;Staffurth, 1962), though none of the report concerning actual determination of intracellular water and electrolytes has been published.…”

“…Skeletal muscle tissue analysis of the human being in normal or pathological conditions were published by many authors (Mudge and Vislocky, 1949;Baldwin et al, 1952;Mokotoff et al, 1952;Talso et al, 1953;Wilson, 1955;Barnes et al, 1957;Litchfield and Gaddie, 1958;Nichols, 1958;Flear and Crampton, 1960;Bergstrom, 1962). In determining the distribution of ions within biopsied samples, chloride space was frequently to be a measure of the extracellular space.…”