PubMed Health⌕ Search

Biomedical subjects

M M Trujillo

Publications and source records attributed to M M Trujillo.

3 recordsLinked to original sources
PubMed2002

Okadaic acid, useful tool for studying cellular processes.

One of the most interesting groups of substances of marine origin, from structural and pharmacological points of view are polyether toxins, which generally present a great diversity in size and potent biological activities. The subject of this review is limited to okadaic acid (OA). It was the first example of a group of polyether toxins produced by marine microalgae, which is responsible for the natural phenomena known as Diarrhetic Shellfish Poisoning, DSP red tides. These toxins are accumulated in the digestive glands of the shellfish with a disastrous effect upon the shellfish industry in many parts of the world. Thus, it has been demonstrated that OA is a highly selective inhibitor of protein phosphatases type 1 (PP1) and 2A (PP2A), subsequently that it causes dramatic increases in phosphorylation of numerous proteins as well as being a potent tumour promoter. For that reason, OA is an extremely useful tool for studying the cellular processes that are regulated by reversible phosphorylation of proteins as signal transduction, cell division and memory.

Amino Acid Sequence↗
PubMed2000

Cellular mechanisms involved in iso-osmotic high K+ solutions-induced contraction of the estrogen-primed rat myometrium.

The aim of the present study was to investigate the mechanisms involved in the contraction evoked by iso-osmotic high K+ solutions in the estrogen-primed rat uterus. In Ca2+-containing solution, iso-osmotic addition of KCl (30, 60 or 90 mM K+) induced a rapid, phasic contraction followed by a prolonged sustained plateau (tonic component) of smaller amplitude. The KCl (60 mM)-induced contraction was unaffected by tetrodotoxin (3 microM), omega-conotoxin MVIIC (1 microM), GF 109203X (1 microM) or calphostin C (3 microM) but was markedly reduced by tissue treatment with neomycin (1 mM), mepacrine (10 microM) or U-73122 (10 microM). Nifedipine (0.01-0.1 microM) was significantly more effective as an inhibitor of the tonic component than of the phasic component. After 60 min incubation in Ca2+-free solution containing 3 mM EGTA, iso-osmotic KCl did not cause any increase in tension but potentiated contractions evoked by oxytocin (1 microM), sodium orthovanadate (160 micrM) or okadaic acid (20 microM) in these experimental conditions. In freshly dispersed myometrial cells maintained in Ca2+-containing solution and loaded with indo 1, iso-osmotic KCl (60 mM) caused a biphasic increase in the intracellular Ca2+ concentration ([Ca2+]i). In cells superfused for 60 min in Ca2+-free solution containing EGTA (1 mM), KCl did not increase [Ca2+]i. In Ca2+-containing solution, KCl (60 mM) produced a 76.0 +/- 16.2% increase in total [3H]inositol phosphates above basal levels and increased the intracellular levels of free arachidonic acid. These results suggest that, in the estrogen-primed rat uterus, iso-osmotic high K+ solutions, in addition to their well known effect on Ca2+ influx, activate other cellular processes leading to an increase in the Ca2+ sensitivity of the contractile machinery by a mechanism independent of extracellular Ca2+.

Animals↗