Isolated rat inferior mesenteric artery response to adenosine: possible participation of Na(+)/K(+)-ATPase and potassium channels.
Journal Title: Pharmacological Reports - Year 2005, Vol 57, Issue 6
Abstract
Adenosine (10(-7)-3 x 10(-4) M) produced concentration-dependent and endothelium-independent relaxation of isolated rat inferior mesenteric artery. Application of indomethacin (10(-5) M) or N(G)-nitro-L-arginine (10(-5) M) did did not alter adenosine-elicited relaxation. Conversely, in the presence of high concentration of K(+) (100 mM), ouabain (10(-4)) or combination of tetraethylammonium (5 x 10(-4) M) and glibenclamide (10(-6) M), adenosine-evoked relaxant effect was significantly reduced. In K(+)-free solution, 1-3 mM potassium induced relaxation, which was partially reversed by ouabain (10(-4) M). 1,3-Dipropyl-8-cyclopentylxanthine (10(-9) M), an A(1)-receptor antagonist, did not affect adenosine-evoked relaxation. Oppositely, 8-(3-chlorostyryl)-caffeine (3 x 10(-7)-10(-6) M), a selective A(2A) receptor antagonist, significantly inhibited adenosine-induced relaxation in a concentration-dependent manner (pA(2) = 6.74). These results indicate that in the isolated rat inferior mesenteric artery, adenosine produces endothelium-independent relaxation, which is partly induced by activation of smooth muscle adenosine A(2A) receptors, and further mediated by the activation of smooth muscle Na(+)/K(+)-ATPase and opening of mixed population of K(+) channels.
Authors and Affiliations
Miroslav Radenković, Leposava Grbović, Srdan Pesić, Dragica Stojić
Keywords
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