This study was performed to test the hypothesis that endothelin peptides differentially influence intracellular @entity460 concentration ([ @entity141 ](i)) in preglomerular microvascular smooth muscle cells (MVSMC), in part through activation of endothelin (ET)(A) receptors. Experiments were performed in vitro with the use of single MVSMC freshly isolated from @entity35 preglomerular microvessels. The effect of @entity1827 , @entity19015 , and @entity1826 on [ @entity141 ](i) was measured with the use of the @entity460 -sensitive dye, @entity593 , and standard fluorescence microscopy techniques. Baseline [ @entity141 ](i) averaged 84+/-3 nmol/L (n=141 cells from 23 dispersions). @entity1827 concentrations of 1, 10, and 100 nmol/L evoked peak increases in [ @entity141 ](i) of 48+/-16, 930+/-125, and 810+/-130 nmol/L, respectively. The time course of the [ @entity141 ](i) response was biphasic, beginning with a rapid initial increase followed by a sustained plateau phase or a period during which [ @entity141 ](i) oscillated sharply. Similar responses were observed after @entity19015 administration. In contrast, @entity1826 stimulated monophasic increases in [ @entity141 ](i) of only 14+/-5, 33+/-16, and 44+/-19 nmol/L at peptide concentrations of 1, 10, and 100 nmol/L, respectively. These responses are significantly smaller than responses to @entity1827 or @entity19015 , respectively. The relative contributions of @entity460 mobilization and @entity460 influx in the response to @entity1827 were also evaluated. Removal of @entity460 from the bathing medium did not significantly alter the peak response to 10 nmol/L @entity1827 but abolished the late phase elevation of [ @entity141 ](i). These data demonstrate that endothelin peptides increase [ @entity141 ](i) in preglomerular MVSMC. The concentration-response profiles are consistent with the response involving activation of ET(A) receptors. Furthermore, these results suggest that @entity1827 increases [ @entity141 ](i) by stimulating both the release of intracellular @entity460 and the influx of @entity460 from the extracellular medium.

Endothelin-mediated XXXX signaling in preglomerular smooth muscle cells.

@entity19015 :: ('24324(Tax:10116)', 'Gene') :: ['ET-2'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity1826 :: ('366270(Tax:10116)', 'Gene') :: ['ET-3'] @entity593 :: ('MESH:D016257', 'Chemical') :: ['fura 2'] @entity1827 :: ('24323(Tax:10116)', 'Gene') :: ['ET-1'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca(2+)']
@entity460 :: (MESH:D002118,Chemical) :: ['calcium']
