Effect of subchronic use of unsymmetrical dimethylhydrazine on contractile activity of isolated lymphatic vessels

Introduction. Unsymmetric dimethylhydrazine (UDMH, heptyl) is widely used as a rocket fuel. Heptyl belongs to especially dangerous substances (hazard class I). UDMH with chronic intragastric administration has a cardiotropic effect, which served as the basis for studying its effect on the contractile activity of lymphatic vessels, since they are part of the vascular system. In addition, lymphatic vessels are considered as objects similar in terms of parameters of phase contractile activity with the heart and having a certain commonality of regulatory mechanisms of cardiomyocytes and smooth muscle cells of lymphangions.

Materials and methods. The toxic effect of UDMH was evaluated on a model of isolated rat lymphatic vessels with subchronic intragastric administration of heptyl for 28 days at doses of 0.02; 0.2; and 2 mg/kg.

Results. The use of UDMH in all studied doses led to a decrease in the contractile activity of lymphatic vessels, which manifested itself in the suppression of the frequency and amplitude of contractions and, as a consequence, the integral indicator – minute productivity. At the same time, the tonic voltage increased dose-dependent. When assessing the state of the endothelium of lymphatic vessels using acetylcholine, a decrease (inversion) of the response of lymphangions to the vasodilator was revealed.

Limitations of the study. The study was performed on male white rats and does not take into account gender differences in the effect of NDMG on lymphatic vessels.

Conclusion. As a result of the study, it was found that UDMH in doses of 0.02; 0.2; and 2 mg/kg causes inhibition of the pumping function of lymphatic vessels, due to a violation of the processes of both excitation and contraction in smooth muscle cells of lymphangions.

Compliance with ethical standards. The study was carried out in accordance with the rules of bioethics approved by the European Convention for the Protection of Vertebrates Used for Experimental and Other Purposes and approved by the Local Bioethical Commission of FSUE "Scientific Research Institute GPECH" of the FMBA of Russia.

Contribution of authors:
Nechaykina O.V. — concept and design of the study, collection and processing of material, writing of text;
Petunov S.G. — concept and design of the study, editing;
Laptev D.S. — concept and design of research, editing;
Bobkov D.V. — editing.
All co-authors — approval of the final version of the article, responsibility for the integrity of all parts of the article.

Conflict of interest. The authors declare that there is no conflict of interest.

Acknowledgment. The study was carried out within the framework of the implementation of the state program of the Russian Federation “Development of healthcare”.

Received: August 30, 2023 / Revised: November 1, 2023 / Accepted: December 28, 2023 / Published: February  29, 202