Expression of Kv4.2 and Kv4.3 potassium channels in human umbilical veins from normal, diabetic and hypertensive pregnancies

Objective: A substantial line of evidence indicates that Kv4.2 and Kv4.3 channels are the major components of rapid transient-outward potassium currents (A-type currents). It is speculated that those currents may be involved in the maintenance of the membrane potential, as well as in the regulation of propagation and frequency of action potentials. However, very little is known about the presence and function of A-type currents in human vascular smooth muscles such as human umbilical vein (HUV). Having in mind its crucial role in the proper fetal oxygenation the aim of the study was to determine whether Kv4.2 and Kv4.3 potassium channels are present in HUV smooth muscle and to investigate potential alterations of their expression during maternal pathological conditions - gestational diabetes mellitus (GDM) and pregnancy-induced hypertension (PIH). Materials and methods: Healthy, diabetic and hypertensive pregnancies were subjects of this investigation. Each group was consisted of 6 HUV samples obtained from 6 normal pregnancies, 6 pregnancies with GDM, and 6 pregnancies with PIH. After pharmacology analysis, immunohistochemistry and Western blot were performed. Results: Immunohistochemistry revealed similar expression pattern of both, Kv4.2 and Kv4.3 subunits, in HUV smooth muscle in all groups of patients. Results obtained by Western blot were in agreement with immunohistochemical staining. The expression of Kv4.2 and Kv4.3 subunits was not significantly different between the groups. Conclusion: Collectively, this is the first study that demonstrated presence of Kv4.2 and Kv4.3 potassium channels in the HUV smooth muscle and their preservation during the course of GDM and PIH. These channels are most likely major components of rapid A-type currents that may be relevant for maternal-fetus blood flow and hence fetal development. Also, they may represent sensors for detecting hemodynamic and/or metabolic changes in the local environment.