Alpha 1-adrenergic receptor-mediated phosphoinositide hydrolysis and prostaglandin E2 formation in Madin-Darby canine kidney cells. Possible parallel activation of phospholipase C and phospholipase A2
alpha 1-Adrenergic receptors mediate two effects on phospholipid metabolism in Madin-Darby canine kidney (MDCK-D1) cells: hydrolysis of phosphoinositides and arachidonic acid release with generation of prostaglandin E2 (PGE2). The similarity in concentration dependence for the agonist (-)-epinephrine in eliciting these two responses implies that they are mediated by a single population of alpha 1-adrenergic receptors. However, we find that the kinetics of the two responses are quite different, PGE2 production occurring more rapidly and transiently than the hydrolysis of phosphoinositides. The antibiotic neomycin selectively decreases alpha 1-receptor-mediated phosphatidylinositol 4,5-bisphosphate hydrolysis without decreasing alpha 1-receptor-mediated arachidonic acid release and PGE2 generation. In addition, receptor-mediated inositol trisphosphate formation is independent of extracellular calcium, whereas release of labeled arachidonic acid is largely calcium-dependent. Moreover, based on studies obtained with labeled arachidonic acid, receptor-mediated generation of arachidonic acid cannot be accounted for by breakdown of phosphatidylinositol monophosphate, phosphatidylinositol bisphosphate, or phosphatidic acid. Further studies indicate that epinephrine produces changes in formation or turnover of several classes of membrane phospholipids in MDCK cells. We conclude that alpha 1-adrenergic receptors in MDCK cells appear to regulate phospholipid metabolism by the parallel activation of phospholipase C and phospholipase A2. This parallel activation of phospholipases contrasts with models described in other systems which imply sequential activation of phospholipase C and diacylglycerol lipase or phospholipase A2.
- Research Organization:
- Univ. of California, San Diego, La Jolla
- OSTI ID:
- 6793231
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOLIPIDS
METABOLISM
PROSTAGLANDINS
BIOCHEMICAL REACTION KINETICS
SYMPATHOMIMETICS
ANIMAL CELLS
ARACHIDONIC ACID
CALCIUM
DOGS
ENZYME ACTIVITY
HYDROLYSIS
KIDNEYS
LABELLED COMPOUNDS
LIPASE
NEOMYCIN
PHOSPHORUS COMPOUNDS
TRACER TECHNIQUES
ALKALINE EARTH METALS
ANIMALS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
AUTONOMIC NERVOUS SYSTEM AGENTS
BODY
CARBOXYLESTERASES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DECOMPOSITION
DRUGS
ELEMENTS
ENZYMES
ESTERASES
ESTERS
HYDROLASES
ISOTOPE APPLICATIONS
KINETICS
LIPIDS
LYSIS
MAMMALS
METALS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
REACTION KINETICS
SOLVOLYSIS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques