Objectives Cold is an important factor contributing to the high incidence of hypertension. Large conductance calcium-activated potassium (BKCa) channels modulate vascular smooth muscle tone. The objective of this study is to determine whether BKCa channels in vascular smooth muscle cells (VSMC) play a role in the development of hypertension during chronic exposure to cold.
Methods Forty-eight rats were divided into cold-treated group and control group randomly, and then, rats of cold-treated group were exposed to 4 ± 1° (4 h/day) and rats of another group were kept at 25 ± 1°.
Results Compared to control group, systolic blood pressure of the rats exposed to cold for 2, 4, 6, 8 weeks were increased by 7.14%, 20.42%, 40.54%, 28.74%, respectively. The BKCa current and BKCa peak current density in aortic VSMC increased significantly as the time of exposure to cold went until the 6th week exposure to cold. At the 6th weeks, the BKCa peak current density in the cold exposed group compared to the control group were increased 345.21% (n = 6, P < 0.01). Furthermore, the expression of BKCa channel α-subunit mRNA in the cold-treated rats was higher than control (P < 0.01).
Conclusions Our data showed that BKCa channels have apparent change with the development of hypertension during repeated cold exposure, suggesting that BKCa channel could be thought as a new target for prevention and treating cold-induced hypertension.