Browsing by Issue Date, starting with "1992"
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- Role of the endothelial system in Bay-K-8644 enantiomer and nifedipine vasomodulator action in rat aortaPublication . Verde, Ignacio; Gil-Longo, José; Orallo, Francisco; Campos, Manuel; Calleja, José MariaThe potential importance of the endothelial system in regulating the effects of (−)-Bay K 8644 (0.1 μM), (+)-Bay K 8644 (0.1 μM) and nifedipine (10 nM) on resting tension, on contractile responses to noradrcnaline (NA) and Ca2+ (in a Ca2+-free high-K+ solution), and on basal, NA-induced and K+-induced 45Ca2+ uptake, was investigated in rat aorta rings. Mechanical removal of endothclium considerably potentiated the contractile response induced by NA in standard medium and by Ca2+ in Ca2+-free high-K' (15 mM) medium, but did not modify the response induced by Ca2+ in Ca2+-frcc high-K+ (55 mM) medium or by NA in Ca2+-free medium. Furthermore, the basal 45Ca2+ uptake and that induced by NA (10 μM) or KCl (15 and 55 mM) were similar in endothelium-rubbed and intact rings. (−)-Bay K 8644 (0.1 μM) shifted the NA and Ca2+ concentration-response curves to the left with potentialion of the maximal contraction. However, (+)-Bay K 8644 (0.1 μM) and nifedipine (10 nM) caused a shift to the right, with depression of the maximal contraction. The NA concentration-response curves, and those of Ca2+ in Ca2+-free high-K+ (55 mM) medium, were affected by the drugs to similar extents, and were not modified by the presence or absence of endothelial cells. The drugs tested did not affect resting tension. Basal 45Ca2+ uptake was not modified by either nifedipine or the Bay K 8644 enantiomers. On the other hand, (−)-Bay K 8644 increased with equal effectives both NA- and KCl-induccd 45Ca2+ uptake, whilst (+)-Qay K 8644 and nifedipine inhibited both uptakes. The presence or absence of endothelium did not modify these effects. These results suggest that, in rat aorta, the endothelial system does not modulate either the agonist effect of (−)-Bay K 8644 or the antagonistic effects of (+)-Bay K S644 and nifedipine. Furthermore, our data indicate that the effects of Bay K 8644 enantiomers and nifedipine on the contractile responses and 45Ca2+ uptake elicited by NA and high-K+ (55 mM) solutions are similar.
- Heads for force: on the headhunting complex in Southeast Asia and MelanésiaPublication . Schouten, Maria Johanna ChristinaCross-cultural exploration of the practice of headhunting in various tribal societies in insular Southeast Asia and in South Melanesia, as described by ethnographers since the nineteenth century. Various motives for this practice, as well as beliefs and rituals attached to it nd the gende role involved, are discussed. With data from fieldwork among the inhabitants of Minahasa in northern Sulawesi.
- 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).
- Efecto del endotelio sobre las contracciones inducidas por noradrenalina y K+ en aortas de rata genéticamente hipertensa y rata normotensaPublication . Verde, Ignacio; Orallo, Francisco; Gil-Longo, José; Campos, M.Desde que Furchgott (1, 2) descubrió que la presencia de endotelio era imprescindible para la acción relajante vascular de la acetilcolina, han aparecido diversos y variados estudios que demuestran su participación en la relajación provocada por diversos agentes (ATP, serotonina, histamina, ...) (3. 4, 5, 6). Es mas, se han descrito diversos mecanismos en células del endotelio vascular que, al ser activados, pueden estimular la liberación de varios factores endoteliales (7). También se ha demostrado la existencia de una posible disfunción o mal funcionamiento del sistema endotelial en procesos de hipertensión, debido. bien a una dificultad en la liberación de EDRF (endothelium derived relaxing factor)(8), o bien a un aumento en la liberación de EDCF (endothelium derived contracting factor)(9. 10). Con el objeto de confirmar la Influencia de los procesos de hipertensión sobre el estado del endotelio, en el presente trabajo se estudia la posible modulación por el sistema endotelial de las contracciones inducidas por noradrenalina y. CaCI2 (en media despolarizante) en aorta de rata normotensa e hipertensa.