Altered K(ATP) Channel Subunits Expression and Vascular Reactivity in Spontaneously Hypertensive Rats With Age

ATP-sensitive potassium (K(ATP)) channels link membrane excitability to metabolic state to regulate a series of biological activities including the vascular tone. However, their ability to influence hypertension is controversial. Here we aim to investigate possible alteration of K(ATP) channel in vascular smooth muscles (VSMs) during hypertension development process. In this study, we used 16-week-old spontaneously hypertensive rats (SHRs), 49-week-old SHRs, and their age-matched Wistar-Kyoto rats to study the expression of VSM K(ATP) subunits at the mRNA and protein level and the function of VSM K(ATP) by observing the relaxation reactivity of isolated aorta rings to K(ATP) modulators. We found that the expression of VSM K(ATP) subunits Kir6.1 and sulfonylurea receptor (SUR2B) decreased during hypertension. Moreover, the expression of SUR2B and Kir6.1 in 49-week-old SHRs decreased much more than that in 16-week-old SHRs. Furthermore, the aorta rings of 49-week-old SHRs showed lower reactivity to diazoxide than 16-week-old SHRs. This study suggests that K(ATP) channels in VSM subunits Kir6.1 and SUR2B contribute to modify the functionality of this channel in hypertension with age.