PHOSPHORIC ACID CHANGES IN WORKED MAMMALIAN MUSCLE

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Abstract
Lactacidogen determinations, i.e., maximum NaHCO3-hydrolyzable P less immediately determined acid-soluble inorganic P, and lactic acid determinations before and after 2 hrs. in 2% Na2HPO4 at 40[degree] C, are reported on variously stimulated muscles of decapitated cats. After tetanic stimulation, continued to failure of response, uniform results were not obtained, except for an increase in the water content. After a long series of maximal contractions not carried to complete fatigue, lactacidogen decreased. The muscle with the greatest decrease had also the least available lactic acid and the greatest increase in water. Available lactic acid approximately equaled the glycogen supply, but exceeded it in resting muscles. Restriction of circulation to a working muscle decreased lactacidogen slightly, but a short period of anaerobic work did not do this. During post-mortal changes, after the first 15 min., lactacidogen and glycogen decrease and lactic acid increases.