Serotonin stimulates a Ca2+ permeant nonspecific cation channel in hepatic endothelial cells

The contraction of hepatic endothelial cell fenestrae after exposure to serotonin is associated with an increase in intracellular Ca2+ which is derived from extracellular Ca2+, is inhibited by pertussis toxin and is not associated with activation of phosphoinositol turnover or cAMP. Using cell-attached and excised patches in primary cultures of rat hepatic endothelial cells, we identified a serotonin-activated channel with conductance of 26.4+/-2.3 pS. The channel was also permeant to Na+, K+ and Ca++ but not to anions. In cell-attached patch recordings, addition of serotonin to the bath significantly increased channel activity with Ca2+ or Na+ as the charge-carrying ions. This channel provides a mechanism whereby serotonin can raise the cytosolic Ca2+ concentration in hepatic endothelial cells.