title: Microregional blood flow and high energy phosphates under conditions of high O2 supply in left ventricular subendocardium.
abstract: Blood flow and high energy phosphate (HEP) content were determined simultaneously in multiple microregions of the left ventricular subendocardium in 49 anaesthetized open-chest rabbits, to determine the relationship between the parameters during high O2 supply with hypercapnia and chromonar treatment. ATP and CP content were quantitated in quick-frozen hearts by fluorometry in 1-2 mg sites where perfusion was measured by H2 clearance employing bare-tipped platinum electrodes. Both hypercapnia and chromonar elevated subendocardial tissue perfusion approximately 30% and O2 supply 45% above control. Blood flow was normally distributed with either treatment, but was more homogeneous with hypercapnia. Neither treatment altered absolute levels of either HEP, but the variance of ATP was less than control. CP distribution was normal in both treatments. There was no significant linear correlation between blood flow and HEP under hypercapnia or chromonar treatment. We conclude that tissue HEP content is a variable not only dependent on O2 supply and blood flow, but also on the size of the ATP and CP pool and the energy demand of the local microregion. The variability of ATP in microregions of the rabbit subendocardium is reduced under conditions of high O2 supply.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001784:Blood Gas Analysis; D002302:Cardiac Output / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects*; D005615:Freezing; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology*; D010725:Phosphocreatine / Q000378:metabolism*; D011817:Rabbits
chemical_list: D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D010100:Oxygen