Porcine somatotropes can be separated by Percoll density gradient centrifugation into low (LD) and @entity2101 ( @entity2101 ) subpopulations that differ ultrastructurally and functionally. Here, we report the effects of @entity7704 ( @entity7704 ) on the cytosolic free @entity460 concentration ([ @entity141 ]i) of single LD and @entity2101 somatotropes. Resting [ @entity141 ]i in LD somatotropes was 2-fold higher than in @entity2101 cells. @entity7704 induced [ @entity141 ]i increases in a similar percentage of somatotropes from both subsets. However, amplitude and kinetics of the responses were markedly different. In all responsive LD somatotropes, @entity7704 evoked a rapid initial peak followed by a sustained plateau (plateau-type response). Blockade of extracellular @entity141 entry by 3 mM @entity1098 , 2 mM @entity5303 , or 100 microM @entity1855 completely abolished the plateau phase without affecting the initial @entity141 spike. Conversely, only the plateau phase was preserved in @entity2426 (TG)-treated LD cells. The vast majority of @entity7704 -responsive @entity2101 somatotropes exhibited a transient [ @entity141 ]i peak that returned gradually to baseline (transient-type response). This response was completely blocked by removal of extracellular @entity141 , whereas TG treatment had no effect. Taken together, our results indicate that the response of LD somatotropes to @entity7704 depends on mobilization of @entity141 of both extra- and intracellular origin, whereas that of @entity2101 somatotropes seems to be exclusively dependent on extracellular @entity141 entry through L-type voltage sensitive @entity141 channels (VSCC). These findings are the first to demonstrate a differential effect of @entity7704 on @entity141 mobilization in two somatotrope subpopulations, and suggest the existence of differences in the @entity7704 receptor(s) expressed in each subpopulation and/or in the intracellular signalling pathways activated upon @entity7704 binding.

@entity7704 mobilizes cytosolic free XXXX through different mechanisms in two somatotrope subpopulations from porcine pituitary.

@entity2426 :: ('MESH:D019284', 'Chemical') :: ['thapsigargin'] @entity7704 :: ('2691', 'Gene') :: ['GRF', 'growth hormone-releasing factor'] @entity5303 :: ('MESH:C018021', 'Chemical') :: ['CoCl2'] @entity1855 :: ('MESH:D014700', 'Chemical') :: ['verapamil'] @entity2101 :: ('MESH:C538394', 'Disease') :: ['high density', 'HD'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity1098 :: ('MESH:D004492', 'Chemical') :: ['EDTA']
@entity460 :: (MESH:D002118,Chemical) :: ['calcium']
