Inhibition of Nitric Oxide Synthesis Eliminates Interstitial Adenosine Production During Systemic Hypoxia in Rat Skeletal Muscle

Abstract

The purpose of this study was to examine the relationship between nitric oxide (NO) synthesis and adenosine (Ado) production in the interstitial space of skeletal muscle during systemic hypoxia. In order to accomplish this, microdialysis fibers were inserted into the hindlimb of anesthetized rats and perfused with the following solutions; 1) Ringer's (control), 20 mM SNP (NO donor), 10 mM L‐NAME (NO inhibitor), 500 μM AOPCP (Ado inhibitor) and 10 mM L‐NAME+ 500 μM AOPCP during baseline (100% O2) and hypoxia (10.5% O2). Ringer's perfusion did not result in any changes in interstitial NO concentrations during either baseline or hypoxia. The perfusion of L‐NAME, AOPCP and L‐NAME+AOPCP inhibited (p<0.05) NO production below detection limits, while SNP perfusion increased interstitial NO levels beyond detection limits throughout the experiment. During Ringer's perfusion, interstitial Ado concentrations were increased (p<0.05) during hypoxia (0.07±0.01) and decreased (P<0.05) during recovery (0.05±0.01 μM) as compared to baseline (0.04±0.01 μM). The perfusion of L‐NAME, AOPCP and L‐NAME+AOPCP all inhibited adenosine production to the point where interstitial Ado levels were below detection limits (p<0.05) during baseline, hypoxia and recovery. Surprisingly, the perfusion of SNP also dramatically decreased (p<0.05) the interstitial adenosine concentrations below detectable limits during hypoxia (undetectable) and recovery as compared to baseline. These data demonstrate that interstitial Ado production is very closely linked to NO availability and even under conditions when interstitial Ado production is stimulated (hypoxia), blocking NO availability completely eliminates all interstitial Ado production. These data further indicate that interstitial Ado production is tightly regulated within a narrow range of NO concentrations and a static pool of NO is required for normal interstitial Ado production.Support or Funding InformationSupported by NSERCThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.