PMC

A, change in diameter in response to 10⁻⁷  m SNAP alone (■), 10 mm KCl alone (▲) and 10⁻⁷  m SNAP + 10 mm KCl added together simultaneously (▼). * SNAP alone differed significantly from SNAP + KCl. B, change in diameter in response to 10⁻⁷  m ADO alone (■), 10 mm KCl alone (▲) and 10⁻⁷  m ADO + 10 mm KCl added together simultaneously (▼). * ADO alone differed significantly from ADO + KCl. C, change in diameter in response to 10⁻⁷  m ADO alone (■),10⁻⁷  m SNAP alone (▲) and 10⁻⁷  m ADO + 10⁻⁷  m SNAP added together simultaneously (▼). * SNAP alone differed significantly from ADO + SNAP.

A, change in diameter in response to ADO + KCl in the absence (■) and presence (▲) of BaCl. *ADO + KCl differed significantly from ADO + KCl + BaCl. For comparison, the diameter change in response to ADO only (▼) is shown (data from Fig. ). B, change in diameter in response to ADO + KCl in the absence (■) and presence (▲) of 10⁻⁴  m Oua. *ADO + KCl differed significantly from ADO + KCl + Oua. For comparison, the diameter in response to ADO only (▼) is shown (data from Figure ).

A, PKA inhibitor, PKI does not alter the dilation to ADO when the vessel was pre-exposed to ADO (black bar, n = 8) but significantly attenuates the dilation to ADO when the vessel was not pre-exposed to ADO (hatched bar, n = 6). White bar, control response to ADO (n = 8). B, after pre-exposure to isoproterenol, PKI significantly attenuates the dilation to isoproterenol (n = 6). All bars are group mean ± s.e.m. *Significantly different from control response, P ≤ 0.05. ADO, adenosine; Iso, isoproterenol; PKI, myristoylated PKI[12-22]; PKA, protein kinase A.

A. Pertussis toxin did not affect CXCR4 expression. Pertussis toxin (100 ng/mL) was added to the cells 30 min before Ado and CXCR4 expression was measured by PCR after 2 hours. * P<0.01 vs control (n = 5). B. Chelerythrin blocked the increase of CXCR4 expression induced by Ado. EPC were pre-treated with 10 µmol/L H89, PD98059 or chelerythrin for 15 min before 10 µmol/L Ado treatment for 4 hours. CXCR4 expression was measured by PCR. * P<0.001 vs control. # P<0.01 vs Ado (n = 3). C. A_2B antagonist inhibited CXCR4 over expression induced by Ado. EPC were pre-incubated for 15 min with increasing concentrations of the A_2B antagonist (MRS1754) or vehicle before incubation with 10 µmol/L Ado for 6 hours. CXCR4 expression was measured by flow cytometry. P = 0.02 (n = 3). D. A_2B gene silencing inhibited CXCR4 expression. CXCR4 mRNA expression was measured in EPC transfected with A_2B siRNA or control siRNA for 24 to 48 hours and treated with 10 µmol/L Ado for 4 hours. A_2B siRNA inhibited the increase of CXCR4 expression induced by Ado. * P<0.01 vs control. # P<0.05 vs Ado + control siRNA (n = 3).