In electric field stimulation (EFS) an electrical stimulus is applied uniformly to an isolated tissue in short-wave pulses. Depending on the mediators released by the EFS, tissue contraction or relaxation may occur. Initially, our research group demonstrated that the stimulated contractions of human umbilical cord vessels (HUCV) depend on the presence of the endothelium and are not affected by tetrodotoxin, a sodium channel blocker, used to prevent the release of mediators from nerve endings. Similar findings were found in reptiles. The aorta of the tortoise Chelonoidis carbonaria and the aorta of Crotalus durissus terrificus, Bothrops jararaca and Panterophis guttatus. Recently, basal release of dopamine by HUCV endothelial cells was detected through pharmacological tests and liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS). Dopamine acts in the dopaminergic neurotransmission in the central nervous system, in the modulation of blood pressure by renal and vascular mechanisms and is important in the modulation of cardiac function. The analyzes with LC-MS-MS also revealed a new vascular mediator 6-nitrodopamine. The 6-nitrodopamine is produced from the dopamine nitration. Preliminary tests by our research group identified that 6-nitrodopamine has an important positive chronotropic effect on the right atrium of rats and in the modulation of their blood pressure. The objective of this work is to characterize the pathophysiological and 6-nitrodopamine role released by the umbilical cord endothelium in risk pregnancies, through pharmacodynamic analysis through pharmacological tests and to measure the concentrations of this mediator produced by HUCV through LC-MS- MS comparing with the results obtained in usual risk pregnancies.
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