{'fraction_non_alphanumeric': 0.031315240083507306, 'fraction_numerical': 0.026443980514961725, 'mean_word_length': 5.3628318584070795, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Elevated interstitial ATP concentrations stimulate adenosine production in resting rat skeletal muscle

It has been suggested that muscle contraction is needed for ATP release into the interstitial space and subsequently adenosine production. However, whether elevated interstitial ATP alone in the absence of muscle contraction can increase interstitial adenosine production has yet to be examined. Anesthetized rats had microdialysis fibers inserted into the gastrocnemius muscle of each leg and perfused with saline (control), saline plus 60 uM of ATP (treatment) and then saline (recovery) for 20 min at a rate of 5 uL/min. In vitro probe loss of ATP was determined to be 10.7±0.4%, resulting in a loss of >6 uM of ATP into the interstitium. Dialysate adenosine concentrations increased (P<0.05) from 0.144±0.026 to 0.401±0.049 uM during ATP perfusion, but returned to baseline (0.168±0.22 uM) during recovery. The magnitude of increase in interstitial adenosine concentrations are comparable to those seen during muscle contraction as well as during hypoxia. These results clearly demonstrate that elevated interstitial ATP concentrations are sufficient to stimulate adenosine production without muscle activation. This is most likely due to breakdown of adenine nucleotides by ecto‐5′‐nucleotidase. In summary, adenosine production can be stimulated in resting skeletal muscle independent of muscle contraction. Supported by NSERC.