Nucleotide concentrations in cellular tissues during potassium and magnesium deficiency

Effect of denervation on adenine nucleotides in skeletal muscle from normal and dystrophic mice

The effect of denervation on the adenine nucleotide content of fast- and slow-twitch skeletal muscle of the C57BL mouse was studied by high-performance liquid chromatography. From the adenine nucleotide content the energy charge, a measure of high-energy phosphate available to the cell, was calculated. The energy charge of the extensor digitorum longus muscle was significantly higher than that of the same muscle from dystrophic mice (C57BL/6J dy2j/dy2j) and on denervation decreased to the values found in the innervated muscle from dystrophic animals. Denervation of the muscle in dystrophic mice did not change the energy charge of that muscle. The energy charge of the soleus muscle from both normal and dystrophic mice was similar and did not change on denervation. It is proposed that in the dystrophic process a functional denervation of skeletal muscle occurs which preferentially affects fast-twitch muscle, leading to a reduction in the energy charge.

Measurement of adenosine metabolites and metabolism in isolated tissue preparations

Several pitfalls have been encountered in setting up methodology for the study of adenosine metabolism and quantitation of adenosine metabolites in isolated tissue preparations. Quantitation of metabolites by high-performance liquid chromatography (HPLC) methods has shown that: 1. significant absorbtion of purines to some types of thread (used to tie up tissues in tissue baths) occurs; 2. without particular care in the preparation of tissue baths and medium, significant microbiological contamination can occur; 3. stimulation of guinea pig ileum preparations at 0.2 Hz is associated with weight loss of the tissue and release of purine-degrading enzymes into the bathing medium; 4. stability of purine analogs is dependent on the tissue and species. A method for the measurement of the purines uric acid, xanthine, hypoxanthine, inosine, adenosine, adenine nucleotides, and various substituted nucleotides in medium and tissue samples following incubations of rat vas deferens and guinea pig ileum is presented.