Nucleotide receptors in hepatic stellate cells of the rat

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Abstract
When hepatic stellate cells were stimulated by UTP, ATP, or ADP, cellular levels of inositol phosphates significantly increased (UTP > ATP > ADP > 5′‐O‐(3‐thiotriphosphate). Thirty min after incubation with 100 μM of UTP, ATP, or ADP, levels of inositol monophosphate increased to 1318 ± 116, 616 ± 87 and 591 ± 234% of control levels, respectively, with concomitant increase in the production of inositol trisphosphate and bisphosphate. These nucleotides transiently increased the [Ca2+]i of fura‐2‐loaded stellate cells. Moreover, UTP, ATP, ADP and adenosine 5′‐O‐(3‐thiotriphosphate) were able to induce contraction of stellate cells as detected using the silicone‐rubber membrane method. These results suggested that hepatic stellate cells have nucleotide receptors which react predominantly with extracellular UTP and ATP and trigger the receptormediated contraction of the cells.