Adenosine decreases intracellular free calcium concentrations in cultured vascular smooth muscle cells from rat aorta.
Using an intracellularly trapped dye, quin 2, effects of adenosine on intracellular free calcium concentrations ([Ca2+]i) were recorded, microfluorometrically, using rat aortic medial vascular smooth muscle cells (VSMCs) in primary culture. Regardless of whether cells were at rest (in 5 mM K+), at K+-depolarization (in 55 mM K+) or at Ca2+ depletion (in Ca2+-free media), adenosine induced a rapid reduction of [Ca2+]i, following which there was a gradual increase to pre-exposure levels, in cells at rest and in the case of Ca2+ depletion. Only when the cells were depolarized (55 mM K+) did adenosine induce a new steady [Ca2+]i level, lower than the pre-exposure value. These findings indicate that decrease in [Ca2+]i by adenosine is one possible mechanism involved in the adenosine-mediated vasodilatation, and that adenosine decreases [Ca2+]i by direct extrusion, by sequestration, or by inhibiting the influx of Ca2+ into VSMCs.
D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D001011:Aorta; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D051381:Rats
D000241:Adenosine; D011188:Potassium; D002118:Calcium