Decreased aortic contractile reaction to 5-hydroxytryptamine in rats with long-term hypertension induced by lead (Pb(2+)) exposure.

Male Wistar rats were exposed to 100ppm Pb(2+) in drinking water for 10 months. Tail blood pressure, serum 5-hydroxytryptamine (5-HT), the expression of 5-HT(2B) receptor in the aorta, the aortic response to 5-HT, and the pathologic changes of aorta were examined. The systolic blood pressure of Pb(2+) exposed group was significantly increased after 2 months of Pb(2+) exposure. After 10 months of Pb(2+) exposure, aortic contractile response to 5-HT was significantly decreased. There was no significant difference in the levels of serum 5-HT and the expression of 5-HT(2B) receptor between these two groups. The aortic media and the media-lumen ratio of Pb(2+) exposed group were significantly increased. These data suggest that long-term Pb(2+) exposure can increase blood pressure, and can alter the function and structure of aortic of rats. The decreased aortic response to 5-HT has little relation to the expression of 5-HT(2B) receptor and the serum level of 5-HT, maybe is a result of the aortic structural alteration.