Differential effects of vasopressin and phenylephrine on protein kinase C-mediated protein phosphorylations in isolated hepatocytes

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:7107056

Cooper, R H; Johanson, R A; Wiliamson, J R

Receptor-mediated breakdown of inositol lipids produces two intracellular signals, diacylglycerol, which activates protein kinase C, and inositol trisphosphate, which causes release of intracellular vesicular Ca/sup 2 +/. This study examined the effects of Ca/sup 2 +/-ionophores, vasopressin, phenylephrine, and phorbol ester (PMA) on hepatocyte protein phosphorylations. (/sup 32/P) Phosphoproteins from hepatocytes prelabeled with /sup 32/P were resolved by 2-dimensional SDS-PAGE and corresponding autoradiographs were quantitated by densitometric analysis. The phosphorylation of five proteins, a plasma membrane bound 16 kDa protein with pI 6.4, a cytosolic 16 kDa protein with pI 5.8, and proteins with Mr's of 36 kDa, 52 kDa, and 68 kDa, could be attributed to phosphorylation by protein kinase C since the phosphorylation was stimulated by PMA. When the vasopressin concentration was varied, low vasopressin stimulated the phosphorylation of only the membrane bound 16 kDa protein of the above set of proteins, while higher vasopressin concentrations were required to stimulate the phosphorylation of all five proteins. Phenylephrine, even at supramaximal concentrations, stimulated the phosphorylation of only the membrane bound 16 kDa protein. These results suggest that phenylephrine is a less potent activator of protein kinase C than vasopressin by virtue of limited or localized diacylglycerol production.

• Research Organization: Univ. of Pennsylvania School of Medicine, Philadelphia
• OSTI ID: 7107056
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

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560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALINE EARTH METAL COMPOUNDS
ANIMAL CELLS
AUTORADIOGRAPHY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
CALCIUM COMPOUNDS
CARCINOGENS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELECTROPHORESIS
ESTERS
HORMONES
ISOTOPES
LIGHT NUCLEI
LIVER CELLS
MEMBRANES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PHORBOL ESTERS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORYLATION
PITUITARY HORMONES
PROTEINS
RADIOISOTOPES
SOMATIC CELLS
VASOPRESSIN