In PC12 cells, somatostatin (SRIF) decreases the Ca21 in¯ux in response to high K1 through the inhibition of voltagedependent Ca21 channels. In the present study, we measured the intracellular Ca21 concentration ( [Ca21]i) following the application of SRIF-14 or its analogues which bind to different SRIF subtype (sst) receptors. Their application differentially reduces [Ca21]i (octreotide . SRIF-14 . CGP23996 . BIM23056) in a dose-dependent manner. Pretreatment with a SRIF antagonist prevents the SRIF-induced inhibition of [Ca21]i. These results suggest the involvement of speci®c membrane receptors and are in line with recent ®ndings indicating the presence of receptor mRNAs on PC12 cells. Our results also exclude the possibility that SRIF interacts with opioid receptors and suggest that the SRIF-induced inhibition of [Ca21]i is mediated by mechanisms involving PTX-sensitive G-proteins and PK-dependent pathways.
Mechanisms mediating somatostatin-induced reduction of cytosolic free calcium in PC12 cells
TRAINA, Giovanna;
1999
Abstract
In PC12 cells, somatostatin (SRIF) decreases the Ca21 in¯ux in response to high K1 through the inhibition of voltagedependent Ca21 channels. In the present study, we measured the intracellular Ca21 concentration ( [Ca21]i) following the application of SRIF-14 or its analogues which bind to different SRIF subtype (sst) receptors. Their application differentially reduces [Ca21]i (octreotide . SRIF-14 . CGP23996 . BIM23056) in a dose-dependent manner. Pretreatment with a SRIF antagonist prevents the SRIF-induced inhibition of [Ca21]i. These results suggest the involvement of speci®c membrane receptors and are in line with recent ®ndings indicating the presence of receptor mRNAs on PC12 cells. Our results also exclude the possibility that SRIF interacts with opioid receptors and suggest that the SRIF-induced inhibition of [Ca21]i is mediated by mechanisms involving PTX-sensitive G-proteins and PK-dependent pathways.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
