RESUMEN
Since musculoskeletal impairment increases with age, it is important to determine if exercise changes age-related muscle weakness. This study compared the training effects of electrical stimulation and voluntary isometric contraction, the traditional exercise, on the quadriceps femoris in males 65 years and older. Eighteen informed, nondisabled males, 72 +/- 4 years of age, participated in 12 training sessions over 4 weeks. Maximal voluntary isometric contraction (MVIC) torque was measured with a Cybex II dynamometer prior to and following training. An interclass correlation coefficient (3,1) of 0.982 demonstrated repeated reliable torque measurement. The electrical stimulation group trained at an average of 36% of pretest MVIC; the traditional exercise group trained at an average of 42% MVIC. Average (F = 14.06, p = 0.004) and peak (F = 14.32, p = 0.004) torque values were increased with both modes of training. Both methods of training using a low training load were effective in increasing torque in this older male sample. Electrical stimulation has the same potential as traditional exercise to provide improved strength for aged males. Future research should examine electrical stimulation in older persons with compromised ability to exercise using traditional methods.
Asunto(s)
Estimulación Eléctrica , Contracción Isométrica/fisiología , Músculos/fisiología , Esfuerzo Físico/fisiología , Muslo/fisiología , Anciano , Ejercicio Físico/fisiología , Humanos , Masculino , Pulso Arterial/fisiología , Factores de TiempoRESUMEN
A series of alpha-amino-3-(phosphonoalkyl)-2-quinoxalinepropanoic acids was synthesized and evaluated for NMDA receptor affinity using a [3H] CPP binding assay. Functional antagonism of the NMDA receptor complex was evaluated in vitro using a stimulated [3H]TCP binding assay and in vivo by employing an NMDA-induced seizure model. Some analogues also were evaluated in the [3H]-glycine binding assay. Several compounds of the AP-6 type show potent and selective NMDA antagonistic activity both in vitro and in vivo. In particular alpha-amino-7-chloro-3-(phosphonomethyl)-2-quinoxalinepropanoic acid (1) displayed an ED50 of 1.1 mg/kg ip in the NMDA lethality model. Noteworthy is alpha-amino-6,7-dichloro-3-(phosphonomethyl)-2-quinoxalinepropanoic++ + acid (3) with a unique dual activity, displaying in the NMDA receptor binding assay an IC50 of 3.4 nM and in the glycine binding assay an IC50 of 0.61 microM.
Asunto(s)
2-Amino-5-fosfonovalerato/análogos & derivados , N-Metilaspartato/antagonistas & inhibidores , 2-Amino-5-fosfonovalerato/síntesis química , 2-Amino-5-fosfonovalerato/metabolismo , 2-Amino-5-fosfonovalerato/farmacología , Animales , Unión Competitiva , Encéfalo/metabolismo , Técnicas In Vitro , Masculino , Ratones , Modelos Moleculares , Conformación Molecular , N-Metilaspartato/toxicidad , Quinoxalinas/síntesis química , Quinoxalinas/farmacología , Ensayo de Unión Radioligante , Ratas , Receptores de N-Metil-D-Aspartato/metabolismoRESUMEN
The purpose of this study was to extend our previous work with the auditory-evoked brainstem response and determine whether galactosemia would produce a functional neuropathy similar to that previously seen in streptozocin-induced diabetic rats. Sprague-Dawley male rats implanted with cortical electrodes received either normal chow (n = 17) or a 50% galactose diet (n = 17) for 5 weeks. Peak II latency of the auditory-evoked brainstem response, interpreted as a functional measure of the auditory nerve (VIII cranial) in rats, was significantly prolonged in galactose-fed rats relative to controls (P less than 0.05). These results demonstrate a functional deficit in the auditory nerves of galactosemic rats. The deficit in the auditory-evoked brainstem response of galactosemic rats is similar to our previous finding in streptozocin-induced diabetic rats.
Asunto(s)
Potenciales Evocados Auditivos , Galactosemias/fisiopatología , Nervio Vestibulococlear/fisiopatología , Animales , Tronco Encefálico/fisiopatología , Catarata/etiología , Galactosemias/complicaciones , Masculino , Ratas , Ratas EndogámicasRESUMEN
The behavioral effects of several new anxiolytics and putative anxiolytics were evaluated in two tests sensitive for anxiolytic activity. In the first test, rats were trained to lever-respond for sweetened milk under a multiple variable-interval fixed-ratio (VI-FR) schedule of reinforcement. In the FR component a brief electric shock coincided with the presentation of reward (i.e. conflict procedure). Treatment of these rats with diazepam, tracazolate, CGS-9896, and the pyrimidinylpiperazine derivatives buspirone, gepirone and ipsapirone (TVX Q 7821) significantly increased responding that was suppressed by foot-shock. A common metabolite of the pyrimidinylpiperazines, l-PP, had no affect on punished responding. A second group of rats was trained to discriminate diazepam from saline using a two-lever operant choice procedure. Diazepam-stimulus generalization occurred to CGS-9896, CL 218,872, zopiclone and tracazolate, but not to buspirone, gepirone, ipsapirone or l-PP. It was concluded that while all of the new compounds examined appear to share an anxiolytic effect as demonstrated by their activity in the conflict procedure, the pyrimidinylpiperazine agents do not share discriminative stimulus properties which are common to drugs which act via the benzodiazepine receptor.