Vassilev Petar, Zaytseva Ekaterina, Ardasheva Raina, Turiyski Valentin
Medical University of Plovdiv, Plovdiv, Bulgaria.
Folia Med (Plovdiv). 2023 Feb 28;65(1):116-123. doi: 10.3897/folmed.65.e73081.
The present study was conducted in an attempt to find possible direct mechanisms of action of Clostridium difficile toxins A and B (TCdA and TCdB) on contractility of isolated rat intestinal smooth muscles, as the contractive pathways affected by the toxins and responsible for motility disorders remain unclear.
Adult male Wistar rats were used in our experiments. Longitudinal smooth muscle (SM) preparations of proximal colon were isolated and their contractile activity was isometrically registered. The samples were mounted in tissue baths and exogenously treated with acetylcholine (ACh), serotonin (5-HT), dopamine, norepinephrine, TCdA and TCdB. The potential of TCdA and TCdB to affect the action of these mediators on SM activity was examined.
The experiments have shown that exciting action of ACh and 5-HT on colonic contractility is enhanced by TCdA rather than TCdB. Conversely, relaxing effect of dopamine and norepinephrine on contractile activity of colonic SM is under impact of TCdB but not TcdA. TCdA has a stronger direct effect on in vitro SM sensitivity to ACh and 5-HT than TCdB.
TCdA and TCdB affect directly the contractile reactivity of isolated rat colon smooth muscle. TCdA has a stronger direct effect on smooth muscle sensitivity to acetylcholine and 5-HT than TCdB. Such a trend has not been established for dopamine and norepinephrine.
本研究旨在探寻艰难梭菌毒素A和B（TCdA和TCdB）对离体大鼠肠道平滑肌收缩性可能的直接作用机制，因为受毒素影响且导致运动障碍的收缩途径仍不清楚。
成年雄性Wistar大鼠用于我们的实验。分离出近端结肠的纵行平滑肌（SM）标本，并对等长记录其收缩活性。将标本置于组织浴槽中，并用乙酰胆碱（ACh）、血清素（5-HT）、多巴胺、去甲肾上腺素、TCdA和TCdB进行外源处理。研究了TCdA和TCdB影响这些介质对SM活性作用的可能性。
实验表明，TCdA而非TCdB增强了ACh和5-HT对结肠收缩性的兴奋作用。相反，多巴胺和去甲肾上腺素对结肠SM收缩活性的舒张作用受到TCdB而非TcdA的影响。与TCdB相比，TCdA对体外SM对ACh和5-HT的敏感性具有更强的直接作用。
TCdA和TCdB直接影响离体大鼠结肠平滑肌的收缩反应性。与TCdB相比，TCdA对平滑肌对乙酰胆碱和5-HT的敏感性具有更强的直接作用。多巴胺和去甲肾上腺素未呈现出这样的趋势。
