TY - JOUR

T1 - ATP release and extracellular nucleotidase activity in erythrocytes and coronary circulation of rainbow trout

AU - Jensen, Frank B

AU - Agnisola, Claudio

AU - Novak, Ivana

N1 - Keywords: ATP release; ATP signaling; Ectonucleotidase activity; E-NTPDase; Extracellular ATP; Red blood cells; Erythrocyte

PY - 2009

Y1 - 2009

N2 - The present study tested the hypothesis that rainbow trout erythrocytes release ATP upon deoxygenation, a mechanism that enables mammalian erythrocytes to produce local vasodilation. We also investigated ATP release and ectonucleotidase activity in the coronary circulation of the isolated trout heart. Erythrocytes suspended in an albumin-containing saline and equilibrated at physiological Pco(2) showed negligible hemolysis (<0.1%), and notably they released small amounts of ATP. The elevation of extracellular [ATP] was higher in the presence of the ectonucleotidase inhibitor ARL 67156 than in its absence, revealing the presence of ectonucleotidase activity. The induction of either a slow (minutes) or a fast (seconds) decrease in hemoglobin O(2) saturation did not lead to additional ATP release. An elevation of Pco(2) was also without influence on erythrocyte ATP release. In the saline-perfused coronary circulation, [ATP] increased as the perfusate moved through the vessels in the presence of ARL 67156. When ATP was added to the inflowing saline, most ATP disappeared during passage of the coronary bed when ARL 67156 was absent but not when it was present. We conclude that rainbow trout erythrocytes and vasculature possess the key elements for ATP signaling, i.e. cellular ATP release and balanced ATP degradation by ectonucleotidases, but that erythrocyte ATP release is not influenced by oxygenation degree. The latter is suggested to be related to the lack of a deoxygenation-dependent interaction of trout hemoglobin with the cytoplasmic domain of band 3.

AB - The present study tested the hypothesis that rainbow trout erythrocytes release ATP upon deoxygenation, a mechanism that enables mammalian erythrocytes to produce local vasodilation. We also investigated ATP release and ectonucleotidase activity in the coronary circulation of the isolated trout heart. Erythrocytes suspended in an albumin-containing saline and equilibrated at physiological Pco(2) showed negligible hemolysis (<0.1%), and notably they released small amounts of ATP. The elevation of extracellular [ATP] was higher in the presence of the ectonucleotidase inhibitor ARL 67156 than in its absence, revealing the presence of ectonucleotidase activity. The induction of either a slow (minutes) or a fast (seconds) decrease in hemoglobin O(2) saturation did not lead to additional ATP release. An elevation of Pco(2) was also without influence on erythrocyte ATP release. In the saline-perfused coronary circulation, [ATP] increased as the perfusate moved through the vessels in the presence of ARL 67156. When ATP was added to the inflowing saline, most ATP disappeared during passage of the coronary bed when ARL 67156 was absent but not when it was present. We conclude that rainbow trout erythrocytes and vasculature possess the key elements for ATP signaling, i.e. cellular ATP release and balanced ATP degradation by ectonucleotidases, but that erythrocyte ATP release is not influenced by oxygenation degree. The latter is suggested to be related to the lack of a deoxygenation-dependent interaction of trout hemoglobin with the cytoplasmic domain of band 3.

U2 - 10.1016/j.cbpa.2008.11.007

DO - 10.1016/j.cbpa.2008.11.007

M3 - Journal article

C2 - 19049894

VL - 152

SP - 351

EP - 356

JO - Comparative biochemistry and physiology. Part A, Molecular &amp; integrative physiology

JF - Comparative biochemistry and physiology. Part A, Molecular &amp; integrative physiology

SN - 1095-6433

IS - 3

ER -