title: Effects of trans- and cis-resveratrol on Ca2+ handling in A7r5 vascular myocytes.
abstract: Although the natural polyphenol resveratrol posses a direct vasorelaxant effect, its effects on cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) in vascular cells remain still unclear. Here, we have investigated the effects of the isomers trans- and cis-resveratrol on agonist- and high-K(+)-induced [Ca(2+)](i) increases and on voltage-activated transmembrane Ca(2+) fluxes using imaging and patch-clamp techniques in vascular A7r5 myocytes. Arginine vasopressin (AVP) or angiotensin II caused a biphasic increase in [Ca(2+)](i) that was reduced by preincubation with trans-resveratrol and cis-resveratrol. Both isomers also reduced the agonist-induced increase in [Ca(2+)](i) in absence of extracellular Ca(2+). In high-K(+) Ca(2+)-free solution, reintroduction of Ca(2+) caused a sustained rise in [Ca(2+)](i) that was reduced by preincubation with trans-resveratrol or cis-resveratrol. When the isomers were applied during the plateau phase of the agonist- or the high-K(+)-induced response, a biphasic change in [Ca(2+)](i) was observed: a transient reduction of the plateau (<5 min) followed by an increase (>10 min). Finally, trans-resveratrol and cis-resveratrol inhibited voltage-dependent L-type Ca(2+) currents (I(Ca(L))). In conclusion, resveratrol isomers exert a dual effect on [Ca(2+)](i) handling in A7r5 myocytes: 1) a blockade of I(Ca(L)) and 2) an increase in [Ca(2+)](i) by depletion of intracellular Ca(2+) stores (which interferes with the agonist-induced release of intracellular Ca(2+)) and influx of Ca(2+), mainly due to activation of capacitative Ca(2+) entry, although other Ca(2+)-permeable channels are also involved. Taken together, these effects may explain, in part, the endothelium-independent vasorelaxant effects of resveratrol in rat aorta.
authors.affiliation: Departamento de Farmacoloxía, Facultade de Farmacia. Universidade de Santiago de Compostela. Campus Universitario Sur, E-15782, Santiago de Compostela, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Campos-Toimil
authors.forename: Jacobo
authors.initials: J
authors.lastname: Elíes
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Alvarez
authors.forename: Ignacio
authors.initials: I
authors.lastname: Verde
authors.forename: Francisco
authors.initials: F
authors.lastname: Orallo
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D001127:Arginine Vasopressin / Q000494:pharmacology; D001808:Blood Vessels / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D005456:Fluorescent Dyes; D016257:Fura-2; D008564:Membrane Potentials / Q000187:drug effects; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D000077185:Resveratrol; D012433:Ryanodine / Q000494:pharmacology; D013237:Stereoisomerism; D013267:Stilbenes / Q000494:pharmacology*