TY - JOUR
T1 - Intracoronary Angiotensin II causes inotropic and vascular effects via different paracrine mechanisms
AU - Castillo-Hernandez, Jesus R.
AU - Rubio-Gayosso, Ivan
AU - Sada-Ovalle, Isabel
AU - Garcia-Vazquez, Alicia
AU - Ceballos, Guillermo
AU - Rubio, Rafael
N1 - Funding Information:
Supported by Consejo Nacional de Ciencia y Tecnologia G34998-N and SIHGO 20000202018.
PY - 2004/5
Y1 - 2004/5
N2 - We hypothesized that Angiotensin II (Ang II), like other circulating hormones, acts exclusively intravascularly. To activate or block solely intravascular Ang II receptors, Ang II and its peptide receptor blocker saralasin (Sar) were covalently coupled to a inert polymer (POL, MW >4000 kD) forming Ang II-POL and Sar-POL. These two nonpermeable polymers, Ang II and Sar, were intracoronarily administered into the isolated, saline-perfused rat hearts. Ang II-POL and Ang II caused a dose-dependent ventricular positive inotropic (+I) and vasoconstrictor effects (+V) which were blocked by Sar. Sar-POL blocked their +I but not their +V. Thus, Ang II and Ang II-POL act on endothelial luminal receptors through paracrine mechanisms. +I were blocked solely by purinoceptor antagonists and paralleled by augmented venous release of ATP degradation products (adenosine, inosine and hypoxanthine). In contrast, +V were blocked solely by aspirin, indomethacin or a thromboxane A 2 receptor antagonist. Intracoronary administration of ATP-γ-S and U46169, a purinergic, and TXA2 agonists, respectively, mimicked +I and +V. The results indicate that ATP is the paracrine inotropic mediator while thromboxane A 2 is the vasoconstrictor mediator. Thus, the +I and +V distinct effects by intracoronary Ang II indicate that its diverse mechanism of action along the coronary vascular tree may be due to a functionally heterogenous endothelium.
AB - We hypothesized that Angiotensin II (Ang II), like other circulating hormones, acts exclusively intravascularly. To activate or block solely intravascular Ang II receptors, Ang II and its peptide receptor blocker saralasin (Sar) were covalently coupled to a inert polymer (POL, MW >4000 kD) forming Ang II-POL and Sar-POL. These two nonpermeable polymers, Ang II and Sar, were intracoronarily administered into the isolated, saline-perfused rat hearts. Ang II-POL and Ang II caused a dose-dependent ventricular positive inotropic (+I) and vasoconstrictor effects (+V) which were blocked by Sar. Sar-POL blocked their +I but not their +V. Thus, Ang II and Ang II-POL act on endothelial luminal receptors through paracrine mechanisms. +I were blocked solely by purinoceptor antagonists and paralleled by augmented venous release of ATP degradation products (adenosine, inosine and hypoxanthine). In contrast, +V were blocked solely by aspirin, indomethacin or a thromboxane A 2 receptor antagonist. Intracoronary administration of ATP-γ-S and U46169, a purinergic, and TXA2 agonists, respectively, mimicked +I and +V. The results indicate that ATP is the paracrine inotropic mediator while thromboxane A 2 is the vasoconstrictor mediator. Thus, the +I and +V distinct effects by intracoronary Ang II indicate that its diverse mechanism of action along the coronary vascular tree may be due to a functionally heterogenous endothelium.
KW - ATP and thromboxane release
KW - Coronary vascular endothelial heterogeneity
KW - Intravascular Angiotensin II receptors
UR - http://www.scopus.com/inward/record.url?scp=10444274922&partnerID=8YFLogxK
U2 - 10.1016/j.vph.2004.08.002
DO - 10.1016/j.vph.2004.08.002
M3 - Artículo
C2 - 15607498
SN - 1537-1891
VL - 41
SP - 147
EP - 158
JO - Vascular Pharmacology
JF - Vascular Pharmacology
IS - 4-5
ER -