Erowid References Database
Anton PG, Duncan ME, McGrath JC.
“An Analysis of the Anatomical Basis for the Mechanical Response to Motor Nerve Stimulation of the Rat Vas Deferens. Further Evidence for Adrenergic Transmission in the Human Vas Deferens.”.
The mechanical response to motor nerve stimulation of the vas deferens of rat and man was studied. Methods In studies using male Wistar rats (250-300 g) the motor nerve pathway to the tissue was stimulated at different points between the vertebral outflow and the intramural fibers in the pithed rat and in isolated tissues to determine if 2 anatomically separate groups of neurones were involved in the biphasic response. In order to determine whether different groups of smooth muscle fibers were involved in the 2 phases different preparations of isolated tissue were used. In other studies the responses to field stimulation of the motor nerves were monitored in circular and longitudinal smooth muscle layers of isolated portions of vas deferens from healthy male patients undergoing elective vasectomy, and from guinea pigs, mice and rabbits. Drugs used in studies included pancuronium bromide (Organon), reserpine (Koch-Light), guanethidine (CIBA-Geigy), hexErmethonium (Koch - Light), LSD (Sandoz), noradrenaline (Koch-Light), phentolamine (CIBA-Geigy) and yohimbine (BTL). Results Fibers mediating both phases of the biphasic response arose from the upper lumbar vertebral outflows. Pre- or post-ganglionic stimulation elicited both phases and both were inhibited by hexamethonium (1 mg/kg, i.v.). However, the initial twitch phase was relatively resistant to this blockade in the pithed animal or with hypogastric nerve stimulation in isolated tissue. In rat vas deferens preparations perfused through the lumen in situ or in vitro the perfusion pressure response to motor nerve stimulation also showed 2 phases. Studies on portions of vas deferens showed that the proportions of the 2 phases of response varied along the length of the tissue. At the prostatic end the total response was weak with a dominant twitch, and at the epididymal and the 2 phases were of a comparable magnitude. The 'twitch' phase was relatively susceptible to blockade by LSD and reserpine and the 'secondary' phase to phentolamine. Both phases were equally sensitive to guanethidine. Portions of human vas deferens responded to field stimulation of intramural nerves, or exogenous noradrenaline (10 6-lo 4 M) with rhythmical contractions of both circular and longitudinal muscle layers. Field stimulatioln of guinea-pig and rabbit preparations produced an initial rapid 'twitch' response not seen in human preparations. Phenotlamine and yohimbine depressed responses of human vase to field stimulation.
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