Kangrga I, Larew J S, Randic M
Department of Veterinary Physiology, Iowa State University, Ames 50011.
Neurosci Lett. 1990 Jan 1;108(1-2):155-60. doi: 10.1016/0304-3940(90)90723-m.
Bath applied SP (2 x 10(-7) to 5 x 10(-7) M) produced a significant increase in the concentration of glutamate in the spinal slice perfusate, whereas the efflux of aspartate increased only with a higher concentration of SP (5 x 10(-6) M). The enhancement of the basal efflux of glutamate persisted in the absence of external Ca2+, but the effect was blocked by (D-Arg1, D-Pro2, D-Trp7,9, Leu11)-SP, a SP analogue claimed to be an antagonist of synthetic SP. Calcitonin gene-related peptide (CGRP 10(-7) M) produced a significant increase in the concentrations of glutamate and aspartate in the perfusate. Neonatal capsaicin treatment prevented the SP-induced increase in the release of glutamate. In contrast, the effect of CGRP was not significantly modified by the capsaicin treatment. These results indicate that SP and CGRP are capable of modulating the basal efflux of endogenous aspartate and glutamate and this modulation may represent one of the mechanisms by which these peptides contribute to primary afferent synaptic transmission.
浴槽应用P物质（2×10⁻⁷至5×10⁻⁷M）可使脊髓切片灌流液中谷氨酸浓度显著升高，而天冬氨酸外流仅在较高浓度的P物质（5×10⁻⁶M）时增加。在无细胞外Ca²⁺时，谷氨酸基础外流的增强仍持续存在，但该效应被（D-精氨酸¹、D-脯氨酸²、D-色氨酸⁷,⁹、亮氨酸¹¹）-P物质阻断，后者是一种据称是合成P物质拮抗剂的P物质类似物。降钙素基因相关肽（CGRP 10⁻⁷M）可使灌流液中谷氨酸和天冬氨酸浓度显著升高。新生期辣椒素处理可阻止P物质诱导的谷氨酸释放增加。相反，辣椒素处理对CGRP的作用无显著影响。这些结果表明，P物质和CGRP能够调节内源性天冬氨酸和谷氨酸的基础外流，这种调节可能是这些肽参与初级传入突触传递的机制之一。
