Figure 4. Salt-Sensitive Hypertension and BP-Lowering Effects of EP3 Antagonism.

A) A separate cohort of mice were first maintained on a low salt chow diet (LSD, 0.3% salt) since weaning and at 12 weeks of age were shifted to a 4% HSD for 5 weeks. Blood pressure was continuously recorded with radiotelemetry at baseline and during these 5 weeks. DG-041 was injected (20 mg/kg/day, subcutaneous) for 4 consecutive days. B) Establishment of salt-sensitive hypertension in S-P467L mice during the first 4 weeks of HSD. Per institutional animal facility regulations, cages were changed once a week (on days 1, 8, 15, and 22). N=10-11. *p<0.05, S-P467L HSD vs NT HSD by two-way ANOVA repeated measurements. C) Average SBP at baseline and at the end of 4 weeks (HSD days 26-28) were plotted. Two-way ANOVA P_genotype: <0.0001; P_diet: 0.001; P_interaction: 0.32. Sidak’s multiple comparisons, *p<0.05, S-P467L vs NT; ^#p<0.05, S-P467L HSD vs S-P467L LSD. See Figure S3 for DBP, MBP, pulse pressure, HR and activity). D-E) Hourly SBP for first two days in week 5 (HSD days 29-30) was consolidated and plotted in 24-hour format (solid blue and solid red). During HSD days 31-34, mice received a subcutaneous injection of DG041 (20 mg/kg/day) at 10AM each day for 4 consecutive days (see protocol in panel A). Averages of SBP during the last two days of DG041 administration (open squares, see supplemental Figure 4 for daily effects) were plotted against the pre-treatment SBP. DG041 (plasma half-life = 4-6 hours, efficacy window = 2-6 hours post s.c. administration) caused transient dipping of BP in S-P467L mice but not in NT controls. F) SBP in the efficacious window between 12PM and 4PM was plotted to show the effect of DG-041. N=10-11. Two-way ANOVA P_genotype: 0.002; P_DG041: <0.0001; P_interaction: 0.022. *p<0.05 S-P467L vs NT before DG041; Sidak’s multiple comparisons, ^#p<0.05 S-P467L after vs before DG041. One outlier was eliminated from the NT group as determined by a Grubb’s test.