Cold Stress On Rats Vascular Smooth Muscle Cell Calcium Channel Expression

Objective：To observe the changes of the blood pressure and expression of vascular smoothmuscle cells calcium channelα1Csubunit (LTCC α1C) in the rats and the rat vascularsmooth muscle cells exposed in low temperature.Methods：①Thirty rats with the weight of (150-180)g SD(Sprague Dawley) wererandomly divided into4groups:1. Control group(N，n=6):animals were exposed to atemperature of25±1℃.2. Cold treated groups(C，n=18): animals were exposed tocold(4±1)℃and relative humidity of70%for4hours per day for2weeks、4weeksand6weeks respectively. Systolic blood pressure (SBP) was measured twice perweek by the tail-cuff method in a room at (25±1)°C. Five readings were taken at oneBP measurement and the average of6readings was recorded as the weeks’ SBP. TheSD rats were sacrificed by cervical dislocation，the thoracic aorta were isolated fromthe rats which were cut into small pieces and fully homogenated in the RNAextraction reagent Trizol.②The rat aortic VSMC was cultured by the adhesion method.VSMC cells wereexposed group [temperature (4±1)℃]， and divided into exposure groups accordingto exposure time.LTCCα1C mRNA expression was determined by RT-PCR.Results：1.The blood pressure of the rats exposed to cold environment was increased. Theblood pressure of experimental of groups began to increase from the first two weeksand there is significant different group with the control (p <0.01).2. The expression of LTCCα1C mRNA of the cold exposure group increasedsignificantly was compared to the control group，(p <0.01).3. There was a significant correlation between the expression of LTCCα1CmRNA and the blood pressure change the rats exposured to cold.4. VSMC was observed under inverted phase contrast microscope and spindle，long spindle-shaped， arranged radially， showing typical "Valley" and "peak" growth phenomenon.5. The calcium ion concentration in rat aortic vascular smooth muscle cells ofrats exposure to cold group was increased significantly compared to the controlgroup，(p <0.01).6. The expression of LTCC α1C mRNA of the cold-exposure group wasincreased，compared with the control group.There is statistically significant differencebetween them(p <0.01).Conclusions：1.Cold stressed hypertension can be induced in rats after exposed to cold.2.The increase of expression of calcium channelα1C subunit (LTCCα1C) in ratsaortic vascular smooth muscle cells exposed to cold was significantly correlated withSBP increased and the duration of the time exposed to cold.3.The increase of VSMC Ca concentration would be the possible pathogenesisof hypertension rats exposed to cold.