Human umbilical artery smooth muscle exhibits a 2-APB-sensitive capacitative contractile response evoked by vasoactive substances and expresses mRNAs for STIM, Orai and TRPC channels

ROLDÁN PALOMO, AR; MARTÍN, P; REBOLLEDO, A; ENRIQUE, N; FLORES, LE; MILESI, V

BIOCELL

INST HISTOL EMBRIOL-CONICET

Lugar: Mendoza; Año: 2012 vol. 36 p. 73 - 81

0327-9545

After depletion of intracellular Ca2+ stores the capacitative response triggers an extracellular Ca2+ influx through store-operated channels (SOCs) which refills these stores. Our objective was to explore if human umbilical artery (HUA) smooth muscle presented this response and if it was involved in the mechanism of serotonin- and histamine-induced contractions. Intracellular Ca2+ depletion by a Ca2+-free extracellular solution followed by Ca 2+ readdition produced a contraction in HUA rings which was inhibited by the blocker of Orai and TRPC channels 2- aminoethoxydiphenyl borate (2-APB), suggesting a capacitative response. In presence of 2-APB the magnitude of a second paired contraction by serotonin or histamine was significantly less than a first one, likely because 2-APB inhibited store refilling by capacitative Ca 2+ entry. 2-APB inhibition of sarcoplasmic reticulum Ca2+ release was excluded because this blocker did not affect serotonin force development in a Ca2+-free solution. The PCR technique demonstrated in HUA smooth muscle the presence of mRNAs for STIM proteins (1 and 2), for Orai proteins (1, 2 and 3) and for TRPC channels (subtypes 1, 3, 4 and 6). Hence, HUA presents a capacitative contractile response triggered by stimulation with physiological vasoconstrictors and expresses mRNAs for proteins and channels previously identified as SOCs.