Adenosine metabolism in small coronary arteries of pig.
Adenosine preferentially relaxes small coronary arteries over large ones, and small bovine coronary arteries are also known to have a higher density of adenosine receptors. Here we report a possible role of adenosine metabolism in this process. Subcellular fractions, from right coronary artery (lumen diameter of 2-3 mm) of pig designated as large coronary artery and its subsequent branches (lumen diameter of 0.5-1 mm) as small coronary arteries, were prepared and characterized. In comparison to the various large artery subcellular fractions, the corresponding small artery fractions were richer in 5'-nucleotidase but poorer in adenosine deaminase. Thus a cascade of events may promote adenosine relaxation in small coronary arteries: higher activity of 5'-nucleotidase leads to production of more adenosine, larger number of receptors allows greater reactivity to adenosine, and lower adenosine deaminase level promotes prolonged action of adenosine.
Grover
A K
AK
Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
Samson
S E
SE
Lee
R M
RM
D015720:5'-Nucleotidase / Q000378:metabolism; D000241:Adenosine / Q000378:metabolism*; D000243:Adenosine Deaminase / Q000378:metabolism; D000818:Animals; D001158:Arteries / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003331:Coronary Vessels / Q000378:metabolism*; D013552:Swine; D014664:Vasodilation
D015720:5'-Nucleotidase; D000243:Adenosine Deaminase; D000241:Adenosine; D002118:Calcium