Objective: Functional association of voltage- dependent calcium and potassium channels (voltage- gated, Ca²⁺-activated and ATP- sensitive) play important role in membrane potential, intracellular Ca2+ and vascular tone regulation. This study was performed to investigate the expression of BK_Ca, voltage-gated Kv 1.5-, Kir 1.2.-subunit of K(ATP)- and L-type calcium channels in rat thoracic aorta smooth muscle (SM). Methods: The vessels were obtained from anesthetized intact and irradiated (6 Gy) male Wistar rats (200-250 g). The effects of whole body g-irradiation on ion channels expression were studied using patch- clamp technique in whole-cell configuration and polymerase chain reaction (PCR) in real time. Results: Our results demonstrated a significant decrease of BK_Ca channels pore-forming a-subunit expression in rat aorta SM after irradiation (more than 50 %, P<0.05, n=10). The mRNA level of other potassium channels were increased significantly following irradiation: Kv 1.5 – from 0.025±0.004 to 0.10±0.016 relative units (P<0.01, n = 6), K(ATP) – from 0.22±0.04 to 0.72±0.07 relative units (P<0.01, n = 6). At the same time, the expression L-type calcium channels in vascular SM had increased fourfold under irradiation impact (P<0.01, n = 6). These differences in gene expression are associated with an increased voltage-gated potassium channels current density. The PCR-analysis data were confirmed electrophysiologycally, and related transmembrane currents were seen changed in the same manner. Our data clearly demonstrate that the changes in ion channels expression in rat vascular SM after irradiation are similar to those in spontaneously-hypertensive rats [Cox R., 2001]. Conclusion: Ca²⁺ and K⁺ channels expression increment may be due to BK_Ca channelopathy compensation, and these mechanisms may be intrinsic to various types of arterial hypertension. Cox R.H. 2002. Vascul Pharmacol 38(1), 13-23