Endothelin-1 stimulates myristoylated alanine-rich C-kinase substrate (MARCKS) phosphorylation in rat cerebellar slices

Exercise training-induced changes in sensitivity to endothelin-1 and aortic and cerebellum lipid profile in rats

The purpose of this work was to study whether exercise training induces changes in the lipid profile of rat aorta and nervous system and in the in vitro intrinsic responsiveness of these tissues to endothel in-1 (ET-1) treatment. The exercise program performed successfully produced the characteristic metabolic alterations of the trained state. Exercise training induced a large and significant increase in the levels of both aortic ethanolamine plasmalogens (PlasEtn) and glucosylceramides. In contrast, a decrease of aortic ceramide and cholesterol levels was evoked by exercise training. ET-1 increased PlasEtn content only in sedentary animals. An exercise-induced increase in cerebellum levels of ceramides and ceramide monohexosides was found. The cerebellum ceramide content was increased by ET-1 more noticeably in sedentary rats than in trained animals. In contrast, cerebral cortex was observed to be largely insensitive to both exercise training and ET-1 treatment. It was concluded that exercise training (i) induces changes in both vascular and cerebellar lipid profiles, the former being much more pronounced than the latter, and (ii) diminishes the aortic and cerebellar sensitivity to ET-1 action.

Microscale purification of proteins exhibiting anomalous electrophoretic migration: application to the analysis of GAP-43 phosphorylation

Quite often, in vivo analysis of posttranslational protein modifications is complicated by the lack of specific antibodies or unsatisfactory immunoprecipitation efficiency. Here, we present an alternative method to immunoprecipitation that takes advantage of the anomalous electrophoretic behavior exhibited by GAP-43. This method can be applied to other proteins which show similar characteristics, such as myristoylated alanine-rich C kinase, NAP-22, and Neurogranin, among others. All these proteins display relative mobility values that depend on the concentration of polyacrylamide used in the resolving gel. Cell extracts or tissue homogenates are first separated by SDS-PAGE in 15% polyacrylamide gels, and the bands containing GAP-43 are identified, excised from the gel, and rerun on a second SDS-PAGE in 7.5% polyacrylamide/6 M urea gels. To quickly identify the position of GAP-43 in the first gel, a small amount of fluorescein-labeled recombinant GAP-43 was added to the initial extracts. The method, applied to the analysis of GAP-43 phosphorylation in rat hippocampal slices, can be typically completed in less than 4 h. The excellent yields of purification obtained contributed to a greater accuracy and increased reliability of the radioactivity measurements. It also allowed further processing of the samples, including the analysis of the different phosphorylation sites by proteolytic digestion and peptide mapping.

Endothelin enhances adenosine and isoprenaline elevated cyclic AMP levels in rat cerebellar slices

In this study, we present evidence showing that endothelin (ET) potentiates the responses to adenosine, to 5'-N-ethylcarboxamidoad, a nonhydrolyzable adenosine agonist, and to isoprenaline. These responses seem to occur through ET-B receptors, as all three endothelin isopeptides have the same potency, sarafotoxin 6c has the same effect as ET-1, BQ-123, an ET-A receptor antagonist has no effect, and BQ-788, an ET-B receptor antagonist that totally suppresses the responses analyzed.

Involvement of sphingolipids in the endothelin-1 signal transduction mechanism in rat brain

In cerebral cortex, endothelin-1 (ET-1) evoked a decrease of 40% in sphingomyelin (SM) levels together with an increase in both ceramide and glycosphingolipid (GSL) levels (100 and 56% respectively). These facts indicate that ET-1 increases sphingomyelinase activity and, possibly, activates the synthesis of GSL. By contrast, in cerebellum ET-1 seems to activate the hydrolysis of both SM and GSL, since the peptide evoked a decrease (near 30%) of their levels concomitantly with an increased production of ceramides (200%). These ceramides are clearly different from those produced in cerebral cortex which come from the SM hydrolysis only. It is suggested that ETB receptor subtype is involved in these responses.