[Changes of the arterial baroreflex sensitivity in one-kidney Grollman hypertensive rats]

The objective of this study was to investigate the changes of arterial baroreflex sensitivity (ABS) in one-kidney Grollman hypertensive rats. The blood pressure was altered with phenylephrine or sodium nitroprusside. Mean arterial pressure (MAP) and pulse interval were recorded simultaneously and the MAP-pulse interval regression line was constructed. All rats were divided into three groups: Grollman-operation group, sham-operated group and normal group. ABS was determined at the 3rd week after operation. The results were as follows: The ABS of the Grollman hypertensive group was significantly lower than that of the sham-operated group (P less than 0.01). After i.v.c. injection of 150 micrograms captopril the MAP of both groups are lowered, but more significantly in Grollman than in the sham-operated group (P less than 0.05, at 35 min after injection). From 35 to 60 min after injection, the MAP of the sham-operated group has practically reached a steady level while that of the Grollman group still shows significant tendency of decline. At 60th min, the ABS of the hypertensive was significantly increased than that measured 60 min before injection (P less than 0.05), while similar measurements for the sham-operated group showed only a slight or much less significant increase. MAP was increased and ABS was decreased by i.v.c. injection of 8 micrograms angiotension II in the normal group. The results of the present investigation indicate that ABS decreases during the development of one-kidney Grollman hypertensive rats, and that this change appears to be related to the increased concentration of angiotension II in the brain.