Navegando por Palavras-chave "DENERVATION"

Agora exibindo 1 - 2 de 2
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Decreased density of binding sites for the Ca2+ channel antagonist [3H] isradipine after denervation of rat vas deferens
    (Elsevier B.V., 1994-05-02) Jurkiewicz, Aron [UNIFESP]; Lafayette, Simone Sette Lopes [UNIFESP]; Nunes, S. H.; Martini, L. C.; Docarmo, LGD; Wanderley, A. G.; Jurkiewicz, N. H.; Universidade Federal de São Paulo (UNIFESP)
    Radioligand binding assays were performed with the selective antagonist of dihydropyridine-sensitive Ca2+ channels [H-3]PN200-110 (isradipine) in rat vas deferens, before and 7 days after denervation, and data were compared with those obtained for K+-induced contractions, which are Ca2+-dependent. the density (B-max) of dihydropyridine binding sites was decreased to almost one-third of its normal value after denervation. the respective affinity (K-D) was not significantly changed. in addition, it was observed that the K+-induced tonic contraction, which corresponded to 55 +/- 2% of the respective phasic contraction, was decreased to 41 +/- 3% after: denervation. It is assumed that the decreased density of Ca2+ channels causes a decrease in K+-induced influx of Ca2+ and consequently of the corresponding tonic contraction. These results indicate that autonomic innervation can regulate the density of dihydropyridine-sensitive Ca2+ channels in the rat vas deferens.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    IN VITRO DENERVATION OF THE RAT VAS-DEFERENS THROUGH HYPOTHERMIC STORAGE
    (Stockton Press, 1992-10-01) Jurkiewicz, Neide Hyppolito [UNIFESP]; Garcia, Antonio G.; Jurkiewicz, Aron [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); UNIV AUTONOMA MADRID
    1 The rat vas deferens was excised, stored at 4-6-degrees-C and tested after 24, 48, 72 or 96 h for its contractile activity and for the presence of innervation.2 The maximal contractile capacity of the vas, tested through cumulative concentrations of barium chloride (3 x 10(-2) m) was progressively reduced from about 110 mm to about 63 mm after 72 h, without further decay after 96 h. Spontaneous rhythmic contractions were practically absent.3 A loss of endogenous pools of catecholamines was indicated by four parameters: (a) a decline of about 80% after 24 h and of more than 95% after 48 h of the contractile effect of the indirect sympathomimetic agonist tyramine; (b) a fall of about 20%, 50% and 85% on the concentration of noradrenaline, respectively after 24, 48 and 72 h; (c) a fall of about 25% and 90% after respectively 24 and 48 h, of the activity of dopamine-beta-hydroxylase (DBH); (d) a decline of noradrenaline-induced histofluorescence on cross sections of the vas.4 A loss of neuronal uptake capacity was indicated by: (a) a progressive variation of the apparent affinity for adrenaline, expressed as pD2 values, that increased by about 1.5 log units (corresponding to a 30 fold potentiation) after 72 h, and (b) a reduction of the ability of cocaine to potentiate the contractile effects of adrenaline.5 The pD2 values for barium chloride, 5-hydroxytryptamine (5-HT) and histamine were not significantly changed, while the corresponding value for acetylcholine was slightly but significantly reduced by about 0.8 log units.6 The maximal heights of concentration-response curves for noradrenaline, acetylcholine, histamine and 5-HT were reduced by 42-66% in relation to controls. However, when this reduction was measured in relation to the corresponding barium effect, by means of the relative responsiveness ratio (rho), a small though significant increase was observed for noradrenaline, and a fall for the other drugs.7 It is concluded that: (1) the values for the various biochemical and pharmacological parameters decline at different rates, though revealing altogether that denervation is completed by at least 85% after 72 h of hypothermic storage; (2) two of the results, i.e., the lack of spontaneous rhythmic contractions and the lack of increased contractile effects for acetylcholine, 5-HT and histamine, indicate that in these conditions the vas is devoid of the so-called nonspecific sips of denervation.