Sjöblom-Widfeldt N, Nilsson H
Department of Physiology, University of Göteborg, Sweden.
Acta Physiol Scand. 1990 Apr;138(4):523-8. doi: 10.1111/j.1748-1716.1990.tb08880.x.
We have previously studied the transmitters involved in, and the calcium dependency of, the neurogenic response to continuous, regular nerve stimulation in small mesenteric arteries from the rat. We have now studied responses to irregular nerve stimulation in these respects. Small mesenteric arteries from rat were mounted into a myograph and the intramural sympathetic nerves were activated by field stimulation. Irregular nerve stimulation was patterned after recorded activity in human cutaneous nerves. The response to irregular stimulation was reduced by only approximately 50% in the presence of the alpha 1-adrenoceptor antagonist prazosin. In particular, responses to low-frequency stimulation were resistant to prazosin. When the extracellular calcium concentration was reduced from 2.5 to 1.0 mM, approximately 50% of the response to irregular nerve stimulation remained. Responses to low-frequency stimulation were particularly reduced. Thus in these arteries the neurogenic response is caused by noradrenaline and a, perhaps purinergic, co-transmitter. The co-transmitter is important for the response to low-frequency stimulation and for the initial part of the contraction caused by high-frequency stimulation. Reducing the calcium concentration affects more strongly the response to low-frequency nerve stimulation.
我们之前研究了大鼠小肠系膜动脉对持续、规律神经刺激的神经源性反应所涉及的递质及其钙依赖性。现在我们在这些方面研究了对不规则神经刺激的反应。将大鼠的小肠系膜动脉安装到肌动描记器中，通过场刺激激活壁内交感神经。不规则神经刺激是根据人类皮神经记录的活动模式设计的。在α1肾上腺素能受体拮抗剂哌唑嗪存在的情况下，对不规则刺激的反应仅降低了约50%。特别是，对低频刺激的反应对哌唑嗪有抗性。当细胞外钙浓度从2.5 mM降至1.0 mM时，对不规则神经刺激的反应仍保留约50%。对低频刺激的反应尤其降低。因此，在这些动脉中，神经源性反应是由去甲肾上腺素和一种可能是嘌呤能的共递质引起的。该共递质对低频刺激的反应以及高频刺激引起的收缩的初始部分很重要。降低钙浓度对低频神经刺激反应的影响更强。
