Haring H, Tøttrup A
Department of Surgical Gastroenterology C. Rigshospitalet, University of Copenhagen, Denmark.
Regul Pept. 1991 Jul 9;34(3):251-60. doi: 10.1016/0167-0115(91)90183-h.
We studied the effect of synthetic porcine galanin on circular and longitudinal oriented strips of pig ileal muscle. Galanin 10(-11)-10(-6) M had no effect on resting tension in the two layers. In circular muscle precontracted with carbachol 10(-6) M, galanin dose-dependently inhibited the amplitude of contractions to a maximum of 33 +/- 8% at 10(-6) M. In longitudinal muscle the amplitude of contractions induced by carbachol 10(-7) M or transmural field stimulation increased after addition of galanin 10(-9)-10(-7) M to a maximum of 21 +/- 6%, while at higher concentrations inhibition occurred. Maximal inhibition was 36 +/- 14% at galanin 10(-6) M. Tetrodotoxin did not influence the effects of galanin in the preparations. The results indicate that in the homologous species galanin inhibits the circular muscle layer, possibly by a direct action on the smooth muscle. In the longitudinal muscle the effect of galanin is apparently excitatory. The inhibition observed with high concentration of galanin could be due to tachyphylaxis and desensitization. Alternatively, an additional population of low affinity, inhibitory receptors may exist.
我们研究了合成猪甘丙肽对猪回肠肌肉环形和纵形肌条的作用。10⁻¹¹ - 10⁻⁶ M的甘丙肽对两层肌肉的静息张力均无影响。在由10⁻⁶ M卡巴胆碱预收缩的环形肌中，甘丙肽剂量依赖性地抑制收缩幅度，在10⁻⁶ M时最大抑制率为33±8%。在纵形肌中，加入10⁻⁹ - 10⁻⁷ M甘丙肽后，由10⁻⁷ M卡巴胆碱或跨壁场刺激诱导的收缩幅度增加，最大增加至21±6%，而在更高浓度时则出现抑制。在10⁻⁶ M甘丙肽时最大抑制率为36±14%。河豚毒素不影响甘丙肽在这些标本中的作用。结果表明，在同源物种中，甘丙肽抑制环形肌层，可能是通过对平滑肌的直接作用。在纵形肌中，甘丙肽的作用明显是兴奋性的。高浓度甘丙肽观察到的抑制可能是由于快速耐受性和脱敏作用。或者，可能存在另一类低亲和力的抑制性受体。
