Jungmann Carolin, Pyzik Sophie-Charlotte, Packeiser Eva-Maria, Körber Hanna, Hoppe Susanne, Mazzuoli-Weber Gemma, Goericke-Pesch Sandra
Reproductive Unit, Clinic for Small Animals, University of Veterinary Medicine Hannover, 30559 Hannover, Germany.
Tierklinik Neustädter Bucht, 23730 Sierksdorf, Germany.
Biology (Basel). 2023 Jun 15;12(6):860. doi: 10.3390/biology12060860.
In pregnant bitches, the response to oxytocin and denaverine hydrochloride in dystocia management is usually poor. To better understand the effect of both drugs on myometrial contractility, the circular and longitudinal muscle layers were examined in an organ bath. For each layer, three myometrial strips were stimulated twice, each with one of three oxytocin concentrations. The effect of denaverine hydrochloride was studied once in direct combination with oxytocin and alone with subsequent oxytocin administration. Contractions were recorded and evaluated for average amplitude, mean force, area under the curve (AUC), and frequency. Effects of different treatments were analyzed and compared within and between layers. In the circular layer, oxytocin significantly increased amplitude and mean force compared to untreated controls regardless of stimulation cycles or concentrations. In both layers, high oxytocin concentrations caused tonic contractions, while the lowest concentration created regular rhythmic contractions. Longitudinal layer tissue responded to oxytocin with a significantly decreased contractility when stimulated twice, presumably a sign of desensitization. Denaverine hydrochloride neither affected oxytocin induced contractions nor showed a priming effect to subsequent oxytocin. Thus, no benefit of denaverine hydrochloride on myometrial contractility was found in the organ bath. Our results suggest a better efficiency of low-dose oxytocin in canine dystocia management.
在怀孕母犬中，催产素和盐酸地那维林在难产处理中的效果通常不佳。为了更好地了解这两种药物对子宫肌层收缩性的影响，在器官浴中对环形和纵形肌层进行了检查。对于每一层，三条子宫肌层条带分别用三种催产素浓度之一进行两次刺激。研究了盐酸地那维林与催产素直接联合使用一次以及随后单独使用催产素时的效果。记录收缩情况并评估平均振幅、平均力量、曲线下面积（AUC）和频率。分析并比较了不同处理在各层内和各层间的效果。在环形层中，无论刺激周期或浓度如何，与未处理的对照组相比，催产素均显著增加了振幅和平均力量。在两层中，高浓度催产素引起强直性收缩，而最低浓度则产生规则的节律性收缩。纵形层组织在两次刺激时对催产素的反应是收缩性显著降低，这可能是脱敏的迹象。盐酸地那维林既不影响催产素诱导的收缩，对随后的催产素也未显示出启动作用。因此，在器官浴中未发现盐酸地那维林对子宫肌层收缩性有任何益处。我们的结果表明低剂量催产素在犬难产处理中效率更高。
