The effect of pithing and of nerve stimulation on the depletion of noradrenaline by reserpine in the rat anococcygeus muscle and vas deferens.

1 The depletion of noradrenaline (NA) in the rat anococcygeus muscle and vas deferens by reserpine and the effect on this of the abolition of nerve activity by pithing and reinforcement of nerve activity by stimulation of the spinal cord outflows has been studied.2 NA depletion of the anococcygeus and vas deferens measured 24 h after reserpine was similar and was related to dose. The heart was depleted faster than the two smooth muscle tissues.3 In the absence of reserpine neither abolition of nerve activity by pithing nor its reinforcement by nerve stimulation had a detectable influence on NA content of the anococcygeus or vas deferens.4 In rats given reserpine (200 mug/kg), increasing nerve activity by spinal stimulation significantly increased NA depletion in both the anococcygeus and the vas deferens when compared with animals pithed but not stimulated. These results confirm that nerve impulse traffic can be an important factor in determining the rate of depletion of NA by reserpine.5 The mechanical response to nerve stimulation in both the vas deferens and anococcygeus was resistant to quite severe depletion of their NA content, with the exception of the initial fast component of the response in the vas. The implications of these results for motor transmission in the vas deferens are discussed.