TY - JOUR
T1 - Sole activation of three luminal adenosine receptor subtypes in different parts of coronary vasculature
AU - Rubio, Rafael
AU - Ceballos, Guillermo
PY - 2003/1/1
Y1 - 2003/1/1
N2 - In isolated guinea pig hearts saline perfused at constant flow, adenosine A1, A2A, and A3 (Ax) agonists covalently bound to a large polymer (Pol; ≫2,000 kDa) were intracoronarily administered, and three effects were studied: dromotropic, vascular and inotropic. The rank order of potencies were the following: dromotropic (Pol-A2A≪≪Pol-A1>Pol-A3) and vascular and inotropic (Pol-A2A≥Pol-A1≫Pol-A3), where the rank order of potency for Pol-Ax depends on the part of the coronary vascular network involved; i.e., there is a vascular heterogeneity. The large size of Pol-Ax prevents extravascular diffusion and causes it to act solely in the endothelial luminal surface. This implies their cardiac effects are due to endothelial mediators. Inhibition of nitric oxide (NO) and prostaglandin (PG) synthesis with NG-nitro-L-arginine methyl ester and indomethacin, respectively, show that the three cardiac effects of Pol-A1 were mediated by NO and PG, whereas for Pol-A2A and Pol-A3 the mediator was mainly NO but not PG. These results suggest that if Pol-Ax activated the corresponding endothelial Ax-receptor subtype, a different mediator would be produced.
AB - In isolated guinea pig hearts saline perfused at constant flow, adenosine A1, A2A, and A3 (Ax) agonists covalently bound to a large polymer (Pol; ≫2,000 kDa) were intracoronarily administered, and three effects were studied: dromotropic, vascular and inotropic. The rank order of potencies were the following: dromotropic (Pol-A2A≪≪Pol-A1>Pol-A3) and vascular and inotropic (Pol-A2A≥Pol-A1≫Pol-A3), where the rank order of potency for Pol-Ax depends on the part of the coronary vascular network involved; i.e., there is a vascular heterogeneity. The large size of Pol-Ax prevents extravascular diffusion and causes it to act solely in the endothelial luminal surface. This implies their cardiac effects are due to endothelial mediators. Inhibition of nitric oxide (NO) and prostaglandin (PG) synthesis with NG-nitro-L-arginine methyl ester and indomethacin, respectively, show that the three cardiac effects of Pol-A1 were mediated by NO and PG, whereas for Pol-A2A and Pol-A3 the mediator was mainly NO but not PG. These results suggest that if Pol-Ax activated the corresponding endothelial Ax-receptor subtype, a different mediator would be produced.
KW - Cardiac function control
KW - Endothelial control
KW - Endothelial heterogeneity
KW - Endothelial mediators
KW - Luminal endothelial receptors
KW - Parenchymal function modulation
UR - http://www.scopus.com/inward/record.url?scp=0037235385&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.00068.2002
DO - 10.1152/ajpheart.00068.2002
M3 - Artículo
SN - 0363-6135
VL - 284
SP - H204-H214
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 1 53-1
ER -