To investigate the effects of artificial cold wave and artificial heat wave on stroke onset in stroke-prone medium-sized renal vascular hypertensive rats（stroke-prone renovascular hypertensive rats, RHRSP）.

Healthy male SD rats（4-6 weeks old) were randomly assigned into experimental group (n=24), sham-operated group (n=8), and control group (n=8). Twenty-four successfully modeled RHRSP rats were randomly assigned into cold wave group, heat wave group, and normal climate group, with 8 rats in each group. After 3 days, the rats in each group were executed and tissue specimens were collected to dete the presence of cerebral hemorrhage, then TTC staining was performed to observe the cerebral infarction, and HE staining was performed to detect the histopathology of the brain. Repeated measures analysis of variance and LSD test were used to compare the differences in blood pressure of rats in each group at different time points（before operation, 4 weeks, 8 weeks, and 12 weeks after operation). One-way analysis of variance and LSD test were used to compare the differences in blood pressure among groups of rats before and after artificial climate chamber treatment. Paired t test was used to compare the difference of blood pressure before and after treatment with artificial climate box in each group. Chi-square test and Fisher 's exact test were used to analyze the incidence of stroke in each group.

The blood pressure value of the experimental group at 12 weeks after operation was higher than that at 8 weeks after operation, 4 weeks after operation, and before operation [(196.63±18.40) mmHg vs (169.43±13.41) mmHg vs (143.80±6.63) mmHg vs (111.37±7.65) mmHg], and the difference was statistically significant (P＜0.05). After the artificial climate chamber treatment, the blood pressure of the cold wave group was higher than that of the normal room temperature group, and the heat wave group [(225.40±19.29) mmHg vs (204.20±8.71) mmHg vs (188.68±10.01) mmHg], and there was a significant difference (P＜0.05 ). In the cold wave group, the blood pressure after artificial climate box treatment was higher than that before treatment [(225.40±19.29) mmHg vs (204.22±18.74) mmHg], and there was a significant difference (t=-2.789, P=0.027). In the heat wave group, the blood pressure after artificial climate box treatment was lower than that before treatment [(188.68±10.01) mmHg vs (205.48±13.73) mmHg] and there was a significant difference (t=3.586, P=0.009). The combination of cold and heat wave group was called the extreme weather group. There were 8 cases of stroke in the extreme weather group, including 3 cases of cerebral infarction caused by cold wave, 2 cases of cerebral hemorrhage, 2 cases of cerebral infarction caused by heat wave, 1 case of cerebral hemorrhage, and 0 cases in the normal climate group. The total number of stroke cases in the extreme weather group was significantly different from that in the normal climate group (χ²=6.000, P=0.022).

Artificial cold wave and heat wave can increase the risk of stroke in stroke-prone renovascular hypertensive rats with renal vascular hypertension.