Human micro- and macrovessel-derived endothelial cells: a comparative study on the effects of adrenaline and a selective adenosine A2-type receptor agonist under normoxic and hypoxic conditions.

Adrenaline is a highly effective stimulator of cyclic AMP (cAMP) production in microvascular endothelial cells (ECs)--HMEC-1, showing only a moderate activity in macrovascular ECs--HUVEC. In both EC preparations, adrenaline acts via beta-type receptors. Selective stimulation of adenosine A(2)-type receptors resulted in comparable increases in cAMP formation in ECs lining micro- and macrovessels. Hypoxia largely suppressed the cAMP effects resulting from stimulation of both beta-adrenoceptors and adenosine A(2) type receptors in ECs of microvessels (HMEC-1). In contrast, hypoxia had only slight effect on these responses in ECs of macrovessels (HUVEC). The present data provide further evidence of functional differences between microvessel- and macrovessel-derived ECs.