Since amlodipine, a long-acting Ca channel blocker, increases both NO and adenosine production in canine hearts, we investigated that amlodipine activates both ecto-5'-nucleotidase responsible for adenosine production and NO synthase (NOS) for NO production in human umbilical venous endothelial cells (HUVECs), and its cellular signaling. We measured activities of ecto-5'-nucleotidase and NOS in HUVECs in the condition with additions of xanthine (100 muM) + xanthine oxidase (1.6 x 10(-3) U/ml) in the presence or absence of amlodipine (1 x 10(-9)-1 x 10(-6) M). Amlodipine increased both ecto-5'-nucleotidase and NOS activities. Xanthine + xanthine oxidase deactivated both NOS and ecto-5'-nucleotidase, and amlodipine increased both activities of NOS and ecto-5'-nucleotidase by 117 +/- 33% and 48 +/- 6%, respectively. Amlodipine phosphorylated p38MAP kinase and that an inhibitor of p38MAP kinase inhibited the amlodipine-induced activation of both NOS and ecto-5'-nucleotidase. Furthermore, amlodipine increased both adenosine and NO production in the canine ischemic hearts. We concluded that amlodipine activates both NOS and ecto-5'-nucleotidase via p38MAP kinase in vitro and enhances both NO and adenosine production in vivo. (C) 2003 Elsevier Inc. All rights reserved.