Plasma ATP during exercise: possible role in regulation of coronary blood flow

Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington Submitted 23 September 2004 ; accepted in final form 18 November 2004 It was previously shown that red blood cells release ATP when blood oxygen tension decreases. ATP acts on microvascular endothelial cells to produce a retrograde conducted vasodilation (presumably via gap junctions) to the upstream arteriole. These observations form the basis for an ATP hypothesis of local metabolic control of coronary blood flow due to vasodilation in microvascular units where myocardial oxygen extraction is high. Dogs ( n = 10) were instrumented with catheters in the aorta and coronary sinus, and a flow transducer was placed around the circumflex coronary artery. Arterial and coronary venous plasma ATP concentrations were measured at rest and during three levels of treadmill exercise by using a luciferin-luciferase assay. During exercise, myocardial oxygen consumption increased 3.2-fold, coronary blood flow increased 2.7-fold, and coronary venous oxygen tension decreased from 19 to 12.9 mmHg. Coronary venous plasma ATP concentration increased significantly from 31.1 to 51.2 nM ( P < 0.01) during exercise. Coronary blood flow increased linearly with coronary venous ATP concentration ( P < 0.01). Coronary venous-arterial plasma ATP concentration difference increased significantly during exercise ( P < 0.05). The data support the hypothesis that ATP is one of the factors controlling coronary blood flow during exercise. adenosine triphosphate; dogs; red blood cells; luciferase Address for reprint requests and other correspondence: E. O. Feigl, Dept. of Physiology and Biophysics, 357290, Univ. of Washington School of Medicine, Seattle, WA 98195-7290 (E-mail: efeigl{at}u.washington.edu )