Receptor-linked early events induced by vasoactive intestinal contractor (VIC) on neuroblastoma and vascular smooth-muscle cells.

Abstract

Vasoactive intestinal contractor (VIC) caused a series of biochemical events, including the temporal biphasic accumulation of 1,2-diacylglycerol (DAG), transient formation of Ins(1,4,5)P3, and increase in intracellular free Ca2+ [( Ca2+]i) in neuroblastoma NG108-15 cells. In these cellular responses, VIC was found to be much more potent in NG108-15 cells than in cultured rat vascular smooth-muscle cells. The single cell [Ca2+]i assay revealed that in the presence of nifedipine (1 microM) or EGTA (1 mM), the peak [Ca2+]i declined more rapidly to the resting level in VIC-stimulated NG108-15 cells, indicating that the receptor-mediated intracellular Ca2+ mobilization is followed by Ca2+ influx through the nifedipine-sensitive Ca2+ channel. Pretreatment with pertussis toxin only partially decreased Ins(1,4,5)P3 generation as well as the [Ca2+]i transient induced by VIC, whereas these events induced by endothelin-1 were not affected by the toxin, suggesting involvement of distinct GTP-binding proteins. The VIC-induced transient Ins(1,4,5)P3 formation coincident with the first early peak of DAG formation suggested that PtdIns(4,5)P2 is a principal source of the first DAG increase. Labelling studies with [3H]myristate, [14C]palmitate and [3H]choline indicated that in neuroblastoma cells phosphatidylcholine (PtdCho) was hydrolysed by a phospholipase C to cause the second sustained DAG increase. Down-regulation of protein kinase C (PKC) by prolonged pretreatment with phorbol ester markedly prevented the VIC-induced delayed DAG accumulation. Furthermore, chelation of intracellular CA2+ completely abolished the second sustained phase of DAG production. These findings suggest that PtdCho hydrolysis is responsible for the sustained production of DAG and is dependent on both Ca2+ and PKC.

• Authors: T Fu, Y Okano, W Zhang, T Ozeki, Y Mitsui, Y Nozawa
• Journal: The Biochemical journal (Biochem J) Vol. 272 Issue 1 Pg. 71-7 (Nov 15 1990) ISSN: 0264-6021 [Print] England
• PMID: 2124805 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Diglycerides
• Intercellular Signaling Peptides and Proteins
• Myristic Acids
• Palmitic Acids
• Peptides
• vasoactive intestinal constrictor
• Myristic Acid
• Palmitic Acid
• Egtazic Acid
• Inositol 1,4,5-Trisphosphate
• Nifedipine
• Choline
• Calcium
• Fura-2

Topics

• Animals
• Calcium (metabolism)
• Cell Line
• Cells, Cultured
• Choline (metabolism)
• Diglycerides (metabolism)
• Egtazic Acid (pharmacology)
• Fura-2
• Inositol 1,4,5-Trisphosphate (metabolism)
• Intercellular Signaling Peptides and Proteins
• Kinetics
• Muscle, Smooth, Vascular (drug effects, metabolism)
• Myristic Acid
• Myristic Acids (metabolism)
• Neuroblastoma
• Nifedipine (pharmacology)
• Palmitic Acid
• Palmitic Acids (metabolism)
• Peptides (pharmacology)