Figure 2.

Arterial pressure response to exogenous ET-1 in DBH-ET_B;ET_Bsl/sl and DBH-ET_B;ET_B+/+ rats. Significant differences (P < 0.001 by paired t test) in the arterial blood pressure responses to acute injection of ET-1, 1 nmol/kg intravenously, are demonstrated in DBH-ET_B;ET_B+/+ and DBH-ET_B;ET_Bsl/sl rats. Measurements were made under ketamine and xylazine anesthesia in the abdominal aorta via a catheter inserted through the femoral artery. ET-1 was given intravenously (i.v.) in the tail. DBH-ET_B;ET_Bsl/sl rats were fed a high-sodium diet for 3 weeks and were treated with amiloride for 3 days before the study. Time of ET-1 injection is indicated by the arrow at the bottom of the figure. ET_B+/+ rats show the prototypic transient depressor response followed by sustained pressor response. The depressor response is absent in DBH-ET_B;ET_Bsl/sl rats. Similar absence of the transient depressor response was also observed in DBH-ET_B;ET_Bsl/sl fed a normal sodium diet before study (data not shown). Crosses indicate DBH-ET_B;ET_Bsl/sl animals that died during the study. Both of the 2 surviving DBH-ET_B;ET_Bsl/sl animals developed retinal hemorrhages seconds after ET-1 injection.