caa a22 4500 469078022 CHVBK 20180323132940.0 cr unu---uuuuu 170328e19921201xx s 000 0 eng 10.1007/BF00168732 doi (NATIONALLICENCE)springer-10.1007/BF00168732 Phospholipase D in heart: basal activity and stimulation by phorbol esters and aluminum fluoride [Elektronische Daten] [Ruth Lindmar, Konrad Löffelholz] Summary: Evidence for a general role of phospholipase D in signal transduction is accumulating. In the present study, the activity of the enzyme was investigated in heart tissue under basal conditions and after addition of phorbol esters or aluminum fluoride (AlF inf4 sup− ; 10 mM NaF plus 10 μM AlCl3). Atria of rats and chickens were incubated with [3H]-myristic acid in order to label preferentially phosphatidylcholine. Under basal conditions, the tissues generated choline and phosphatidic acid (PtdOH), the primary catalytic products of phospholipase D. When 0.5 or 2.0% ethanol was present, [3H]-phosphatidyl-ethanol (PETH) was rapidly formed at the expense of [3H]-PtdOH. This transphosphatidylation reaction is specific for phospholipase D activity. The basal formation of PETH was not inhibited by a Ca2+-free, EGTA-containing medium. - The phorbol ester 4β-phorbol-12β,13α-dibutyrate (PDB), which is known to activate protein kinase C, enhanced the net formation of choline, whereas the inactive 4β-phorbol-13α-acetate (PAc) was ineffective. PDB (0.2 μM), in contrast to PAc, also increased the formation of [3H]-PtdOH and, in the presence of ethanol, of [3H]-PETH. The PDB-evoked formation of PETH occurred again at the expense of PtdOH. Treshold and maximum effective concentrations of PDB were 10 nM and 0.2-0.6 μM, respectively. The effects of PDB on either choline efflux and generation of PETH showed the same Cat+-dependency, i.e., both effects were blocked by a Ca2+-free, EGTA-containing medium, but not by a Ca2+-free medium without EGTA. In protein kinase C-deficient tissue which was prepared by pretreatment with 0.61 μM PDB for 27 h, PDB failed to enhance the formation of PtdOH and PETH. - A1F4−, a known activator of G-proteins, increased not only the tissue content of inositol phosphates, but also markedly enhanced choline efflux and formation of [3H]-PtdOH and PETH. In conclusion, in mammalian and avian atria a high phospholipase D activity was found even under basal conditions. The enzyme was stimulated by protein kinase C and presumably by a G protein. Springer-Verlag, 1992 Phospholipase D nationallicence Protein kinase C nationallicence Phorbol ester nationallicence Aluminum fluoride nationallicence Signal transduction pathways nationallicence Heart nationallicence IP : inositol phosphate nationallicence DAG : diacylglycerol nationallicence PL : phospholipase nationallicence PtdOH : phosphatidic acid nationallicence PETH : phosphatidylethanol nationallicence PDB : 4β-phorbol-12β,13α-dibutyrate nationallicence PAc : 4β-phorbol-13α-acetate nationallicence AlFinf4sup− : aluminum fluoride nationallicence DMSO : dimethylsulfoxide nationallicence Lindmar Ruth Department of Pharmacology, University of Mainz, Obere Zahlbacher Strasse 67, W-6500, Mainz, Federal Republic of Germany aut Löffelholz Konrad Department of Pharmacology, University of Mainz, Obere Zahlbacher Strasse 67, W-6500, Mainz, Federal Republic of Germany aut Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/6(1992-12-01), 607-613 0028-1298 346:6<607 1992 346 210 https://doi.org/10.1007/BF00168732 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00168732 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lindmar Ruth Department of Pharmacology, University of Mainz, Obere Zahlbacher Strasse 67, W-6500, Mainz, Federal Republic of Germany aut NATIONALLICENCE 700 1- Löffelholz Konrad Department of Pharmacology, University of Mainz, Obere Zahlbacher Strasse 67, W-6500, Mainz, Federal Republic of Germany aut NATIONALLICENCE 773 0- Naunyn-Schmiedeberg's Archives of Pharmacology Springer-Verlag 346/6(1992-12-01), 607-613 0028-1298 346:6<607 1992 346 210 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer