Navegando por Palavras-chave "CASTRATION"

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    EFFLUX OF ACETYLCHOLINE IN DIMORPHIC SKELETAL-MUSCLE FROM CASTRATED MALE-RATS
    (Assoc Bras Divulg Cientifica, 1991-01-01) Lima-Landman, Maria Teresa Riggio de [UNIFESP]; Goncalo, M. C.; Lapa, Antonio José [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The effect of testosterone on motor neurons of dimorphic muscles is demonstrable by the increased frequency of miniature end-plate potentials (mepp) and decreased end-plate acetylcholinesterase activity observed in castrated rats. No change occurs in induced acetylcholine (ACh) release. Although these muscles atrophy after castration there is no loss of muscle fibers. In the present study we reinvestigate the neuromuscular transmission in levator ani (LA) muscles from normal (N) adult (120 days) male rats and from rats castrated (C) 30 days before. The measurement of radioactive [H-3]-choline was used to evaluate ACh release since it permits simultaneous estimation of quantal and non-quantal ACh release. The LA muscle was incubated with [H-3]-choline (1-mu-Ci/ml) for 30 min and ACh efflux was measured after washout. The basal release of [H-3]-choline (dpm total tissue radioactivity-1 number of fibers-1) was 296 +/- 33 and 156 +/- 24 in N and C, respectively. Induced ACh release (25 Hz, 5 min) was the same in N and C (653.19 +/- 66.46 and 496.62 +/- 68.67, respectively). These results indicate that castration increased mepp frequency but reduced the total spontaneous release of ACh.
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    LOW DIHYDROPYRIDINE RECEPTOR DENSITY IN VASA DEFERENTIA OF CASTRATED RATS
    (Stockton Press, 1992-02-01) Castillo, CJF; Lafayette, Simone Sette Lopes [UNIFESP]; Caricati-Neto, Afonso [UNIFESP]; Sette, Mario [UNIFESP]; Jurkiewicz, Neide Hyppolito [UNIFESP]; Garcia, Antonio G.; Jurkiewicz, Aron [UNIFESP].; Universidade Federal de São Paulo (UNIFESP); UNIV AUTONOMA MADRID
    Radioligand binding studies in crude membrane preparations of vasa deferentia of normal rats, with the 1,4-dihydropyridine (+)-[H-3]-PN200-110 (isradipine) showed typical saturation isotherms. The binding exhibited a K(D) of 259 +/- 60 pM and B(max) of 144 +/- 20 fmol mg-1 protein. The low K(D) and the stereoselective displacement of (+)-[H-3]-PN200-110 binding by (+)- and (-)-PN200-110 and by nifedipine suggests that these tissues contain dihydropyridine receptors probably coupled to voltage-sensitive, L-type calcium channels. In membrane preparations from vasa deferentia from rats castrated 30 days previously the maximum specific binding was 25 +/- 10 fmol mg-1 protein, representing only 11% of total binding; thus, the calculation of reliable K(D) values was not feasible. These findings suggest that a testicular hormone, possibly testosterone, plays an important role in the regulation of dihydropyridine-sensitive, voltage-dependent calcium channels in the rat vas deferens.