Browsing by Author "Loza, Isabel"
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- Antiserotoninergic activity of 2-aminoethylbenzocyclanones in rat aorta: Structure-activity RelationshipsPublication . Verde, Ignacio; Loza, Isabel; Ferreiro, T. G.; Sanz, F.; Lozoya, E.; Rodriguez, J.; Manaut, F.; Castro, Elena; Fontenla, José Angel; Cadavid, Isabel; Honrubia, M.; Fueyo, J.; Ravina, EnriqueSubcellular targeting of the components of the cAMPdependent pathway is thought to be essential for intracellular signaling. Here we have identified a novel protein, named myomegalin, that interacts with the cyclic nucleotide phosphodiesterase PDE4D, thereby targeting it to particulate structures. Myomegalin is a large 2,324-amino acid protein mostly composed of a-helical and coiled-coil structures, with domains shared with microtubule-associated proteins, and a leucine zipper identical to that found in the Drosophila centrosomin. Transcripts of 7.5–8 kilobases were present in most tissues, whereas a short mRNA of 2.4 kilobases was detected only in rat testis. A third splicing variant was expressed predominantly in rat heart. Antibodies against the deduced sequence recognized particulate myomegalin proteins of 62 kDa in testis and 230–250 kDa in heart and skeletal muscle. Immunocytochemistry and transfection studies demonstrate colocalization of PDE4D and myomegalin in the Golgi/centrosomal area of cultured cells, and in sarcomeric structures of skeletal muscle. Myomegalin expressed in COS-7 cells coimmunoprecipitated with PDE4D3 and sequestered it to particulate structures. These findings indicate that myomegalin is a novel protein that functions as an anchor to localize components of the cAMP-dependent pathway to the Golgi/centrosomal region of the cell.
- Effects of platelet-activating-factor on contractions and 45Ca2+ influx induced by noradrenaline and potassium in rat rubbed and intact aorta - comparison with its hypotensive effect in anesthetized normotensive ratsPublication . Verde, Ignacio; Orallo, Francisco; Loza, Isabel; Alzueta, A. F.; Campos,Manuel; Freire-Garabal, ManuelIn order to clarify the mechanism of hypotensive activity of platelet activating factor (PAF), the effects of this drug on blood pressure in anaesthetized normotensive rats, on KCl- and noradrenaline-induced 45Ca uptake and contractile responses in rat aorta rings with and without endothelium were studied. PAF (3 micrograms kg-1, i.v.) showed long-lasting hypotensive effects in anaesthetized normotensive rats accompanied by a significant increase in heart rate. PAF (0.1-10 microM) did not relax the contractions induced by noradrenaline (10 microM) or K+ (60 mM) in rubbed or intact rat aorta. PAF did not affect the basal uptake of 45Ca2+ nor that induced by the two vasoconstrictor agents. In experiments in a calcium free medium, PAF (10 microM) had no effect on the noradrenaline- (10 microM) induced contractions. These results suggest that the hypotensive activity of PAF in normotensive anaesthetized rats is not due to a direct effect on rubbed and intact rat aorta rings (acting within the cell or blocking Ca2+ influx through L-type transmembrane calcium channels).
- Pharmacological study of several effects of hydralazine in the bisected rat vas deferensPublication . Verde, Ignacio; Campos-Toimil, Manuel; Orallo, Francisco; Gil-Longo, José; Loza, Isabel; Fernandez-Alzueta, AlejandroWe have studied several effects of hydralazine in the bisected rat vas deferens. Hydralazine produced a shift to the left of the concentration-response curve for noradrenaline, with potentiation of the maximal response in both portions of the vas deferens. In contrast it caused a shift to the right of the concentration-response curve for noradrenaline in preparations pretreated with cocaine (inhibitor of catecholamine neuronal uptake), and of the curve for methoxamine and for CaCl2 (in depolarizing medium with K+ 55 mM), in all cases with depression of the maximal response. Hydralazine enhanced the contractions induced by noradrenaline in Ca2+-free medium, except in the presence of cocaine. It had no effect on [3H]noradrenaline neuronal uptake into noradrenergic neurons of the vas deferens, nor did it affect basal or K+-induced 45Ca2+ uptake. These results suggest that hydralazine potentiates the contractions elicited by noradrenergic by a mechanism other than blockade of the neuronal uptake of this catecholamine. Our results also suggest that the inhibition by hydralazine of the contraction elicited by Ca2+ (in Ca2-free depolarizing high-K+ 55 mM solution) and by methoxamine is not due to an action on voltage-dependent Ca2+ channels, but may reflect an intracellular site of action.
- A study of glaucine-induced relaxation of rat aortaPublication . Verde, Ignacio; Orallo, Francisco; Loza, Isabel; Gil-Longo, José; Calleja, José Maria; Cadavid, IsabelThe vasorelaxant effect of glaucine, the major alkaloid of Platycapnos spicata (L.) Bernh., was studied. At concentrations of 10 microM-0.3 mM in normal Krebs solution it was almost equieffective in relaxing K(+)-induced and noradrenaline-induced tension in rat aortic rings without endothelium, with IC50 values of 160 +/- 16 microM and 90 +/- 14 microM respectively. In experiments in a calcium-free medium, 10 microM glaucine strongly inhibited noradrenaline-induced contractions. Glaucine (0.3 mM) did not affect basal uptake of 45Ca, but induced uptake was reduced to 100% (K+) and 97.7% (noradrenaline) of the basal value. These results suggest that glaucine has an intracellular effect and also acts on the cell membrane by blocking voltage-dependent and receptor-operated calcium channels.