Document Detail

Origin of molecular species of diacylglycerol induced by bombesin in smooth muscle cells from rabbit rectosigmoid.
MedLine Citation:
PMID:  9655694     Owner:  NLM     Status:  MEDLINE    
The source of early production of sn-1,2-diacylglycerol (DAG) has for a long time been exclusively linked to hydrolysis of phosphatidylinositol 4,5-diphosphate, which on receptor activation is hydrolyzed into DAG and inositol 1,4,5-trisphosphate. We have investigated the origin of lipid sources of DAG production in smooth muscle cells, in response to contraction induced by peptide agonists. We have performed a quantitative analysis of the molecular species of DAG formed in relation to the known molecular composition of parent phospholipids. The molecular species of phospholipids are sufficiently unique that the phospholipid origin of DAGs and its quantitative contribution to their formation can be measured by HPLC. Cell suspensions (10-15 x 10(6) cells/ml) from the circular muscle of rabbit rectosigmoid were incubated in the presence of the contractile peptide agonist bombesin (BB) at 10(-6) M. Reactions were stopped at different time intervals from 30 s to 4 min. DAGs were extracted, purified by TLC, and benzoylated with benzoic anhydride. The benzoylated DAGs were first purified by TLC and then by normal phase HPLC before they were injected onto a reverse-phase column and eluted isocratically. Furthermore, phospholipids in the lipid extract [phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylethanolamine (PE)] were purified by TLC and similarly analyzed after hydrolysis to DAGs with phospholipase C (PLC). The DAG molecular species profiles for PI, PC, PS, and PE were all unique. Contraction of cells with BB gave noticeable increases (17-55%) in newly formed DAGs. The major phospholipid source of the newly formed DAGs at 30 s was only approximately 30% from PI, and the remainder was from PC. In contrast, after 4 min of BB stimulation, a decrease was seen in newly formed DAGs in the peak specific for PI hydrolysis. The data suggest that BB-induced contraction by activation of PLCs results in hydrolysis of different phospholipids. The DAGs formed as a result are qualitatively and quantitatively distinct. This could be the basis for the kinetically different pattern of sustained contraction observed with BB.
D Sbrissa; A Hajra; K N Bitar
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  275     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1998 Jul 
Date Detail:
Created Date:  1998-08-25     Completed Date:  1998-08-25     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  G138-50     Citation Subset:  IM    
Department of Pediatrics, Division of Gastroenterology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0656, USA.
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MeSH Terms
Bombesin / pharmacology*
Cells, Cultured
Chromatography, High Pressure Liquid
Chromatography, Thin Layer
Colon, Sigmoid / drug effects,  metabolism*
Diglycerides / biosynthesis*,  chemistry,  isolation & purification
Muscle Contraction / drug effects,  physiology
Muscle, Smooth / drug effects,  metabolism*
Phosphatidylcholines / biosynthesis
Phosphatidylethanolamines / biosynthesis
Phosphatidylinositols / biosynthesis
Phosphatidylserines / biosynthesis
Phospholipids / biosynthesis*,  chemistry
Rectum / drug effects,  metabolism*
Tetradecanoylphorbol Acetate / pharmacology
Type C Phospholipases
Grant Support
Reg. No./Substance:
0/Diglycerides; 0/Phosphatidylcholines; 0/Phosphatidylethanolamines; 0/Phosphatidylinositols; 0/Phosphatidylserines; 0/Phospholipids; 16561-29-8/Tetradecanoylphorbol Acetate; 31362-50-2/Bombesin; EC 3.1.4.-/Type C Phospholipases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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