Section 8
Chapter 7,158

Contrasting effects of phorbol dibutyrate and phorbol myristate acetate in rabbit aorta

Villalobos-Molina, R.; Ransanz, V.; Torres-Márquez, M.E.; Hong, E.; García-Sáinz, J.A.

Biochemical and Biophysical Research Communications 171(2): 618-624


ISSN/ISBN: 0006-291X
PMID: 2403351
DOI: 10.1016/0006-291x(90)91191-t
Accession: 007157067

In rat hepatocytes, active phorbol esters inhibited the alpha1-adrenergic stimulation of phosphatidylinositol labeling with the expected potency order: phorbol myristate acetate (PMA) > phorbol dibutyrate (PDB). In contrast, in rabbit aorta the alpha1-adrenergic action was inhibited dose-dependently by PDB but not by PMA. Similarly PDB (but not PMA) induced a strong contraction in rabbit aorta. The phorbol ester-induced contraction developed slowly, was dose-dependent and independent of extracellular calcium. These effects of PDB in rabbit aorta were neither inhibited by the protein kinase inhibitor H-7 nor mimicked by the synthetic diacylglycerol, OAG. Our results raise some doubts on the mechanism(s) through which the actions of PDB take place in rabbit aorta.

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