Biomaterial Database

Involvement of carboxyl groups in the divalent cation permeability of rat parotid gland basolateral plasma membrane. 1993

T Lockwich, and L M Mertz, and I S Ambudkar

Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.

Divalent cation permeability of rat parotid gland basolateral plasma membranes was examined in dispersed parotid acini (by Ca2+ or Mn2+ entry) and in isolated basolateral plasma membrane vesicles (BLMV, by 45Ca2+ influx). Mn2+ entry (fura2 quenching) was about 1.6 fold higher in internal Ca2+ pool-depleted acini (Ca(2+)-depl acini) than in unstimulated cells. Mn2+ entry into Ca(2+)-depl acini was increased at external pH > 7.4 and decreased at pH < 7.4. Pretreatment of Ca(2+)-depl acini with the relatively hydrophobic carboxylic group reagent, N,N'-dicyclohexylcarbodiimide (DCCD, 50 microM for 30 min) resulted in the inhibition of Mn2+ entry into Ca(2+)-depl acini to unstimulated levels. Another hydrophobic carboxyl group reagent, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) and the relatively hydrophilic carboxyl group reagents, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide (CMCD) did not affect Mn2+ entry. Similar to the effects in intact acini, Ca2+ influx into BLMV was decreased when the external pH was lowered below 7.4. Also DCCD (5 mM, 30 min), but not EEDQ, decreased (40%) Ca2+ influx in BLMV. However, unlike in acini, the hydrophilic reagents, EDC, EAC, and CMCD decreased Ca2+ permeability in BLMV and the effects were nonadditive with the decrease induced by DCCD. The aggregate effects of carboxyl group reagents on the Ca2+ and Mn2+ permeability in BLMV and intact acini, respectively, suggest that a critical carboxyl group (most likely accessible from the cytoplasmic side of the plasma membrane) is involved in divalent cation flux in rat parotid acinar cells.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008345	Manganese	A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)
D010306	Parotid Gland	The largest of the three pairs of SALIVARY GLANDS. They lie on the sides of the FACE immediately below and in front of the EAR.	Gland, Parotid,Glands, Parotid,Parotid Glands
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002413	Cations, Divalent	Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.	Divalent Cations
D002463	Cell Membrane Permeability	A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.	Permeability, Cell Membrane
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D004024	Dicyclohexylcarbodiimide	A carbodiimide that is used as a chemical intermediate and coupling agent in peptide synthesis. (From Hawley's Condensed Chemical Dictionary, 12th ed)	DCCD
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia