The effects of lysergic acid diethylamide on the response to field stimulation of the rat vas deferens and the rat and cat anococcygeus muscles.

1. The effect of lysergic acid diethylamid (LSD) on the response to field stimulation in vitro of the rat vas deferens and anococcygeus muscle was examined. 2. LSD in concentrations from 10(-9) to 10(-6) M caused an increase in tone or rhythmic activity in both tissues, effects identical to those produced by guanethidine or tyramine. The motor effects of all three drugs were abolished by phentolamine 2 x 10(-6) M. Methysergide 2 x 10(-7) M given before LSD reduced the motor effect but was ineffective once the LSD contraction had developed. 3. LSD 10(-9) to 10(-6) M reduced and eventually abolished the response to motor adrenergic nerve stimulation in the anococcygeus muscle with no effect on the response to noradrenaline (NA) and no evidence of differential sensitivity according to the number of stimulating pulses. In the vas deferens LSD abolished the initial twitch component with no effect on the secondary slow contraction. LSD had no effect on the response to inhibitory nerve stimulation in the anococcygeus. 4. These results suggest that in the anococcygeus LSD closely resembles guanethidine in its effects as an adrenergic neurone blocking drug with indirect sympathomimetic actions. In the vas deferens these properties would explain the block of the initial twitch component in the motor response to field stimulation and the increase in rhythmic activity but do not explain the resistance of the secondary slow component of the motor response.