Major histocompatibility complex in the rat and blood pressure regulation

The objective of this study was to evaluate whether the major histocompatibility complex of the rat can be related to blood pressure (BP) level and BP response to stress. Blood pressure was determined under light ether anesthesia or during moderate restraint stress in normotensive Lewis rats, in rat strains congenic with respect to their RT1 haplotype [LEW.1A (RT1a) and LEW.1W (RT1u)], and in their recombinant lines LEW.1AR1 (RT1ar1), LEW.1AR2 (RT1ar2), LEW.1WR1 (RT1wr1), and LEW.1WR2 (RT1wr2). Under light ether anesthesia, systolic blood pressure was similar in Lewis, LEW.1A, and LEW.1W rats. There were also no significant differences in blood pressure in LEW.1AR1 and LEW.1AR2 animals when compared with Lewis or LEW.1A rats. In contrast, BP was significantly increased in LEW.1WR2 rats. On the other hand, moderate restraint stress induced a BP increase in animals of all recombinant lines compared to the respective congenic strains. These results confirmed our previous finding in recombinant inbred strains about the significant role of RT1 complex in BP regulation. Moreover, our data indicated that BP can be influenced by interaction of individual regions of the RT1 complex on the genetic background of Lewis strain.