The action of salt and captopril on blood pressure in mice with genetic hypertension

OBJECTIVE: Does captopril lower blood pressure in genetically hypertensive, normotensive and hypotensive mice under normal and salt-loaded conditions? DESIGN AND METHODS: Groups of inbred mice that were genetically hypertensive, normotensive or hypotensive were given one of the following treatments: (a) captopril in drinking water for 7 days; controls were given water. (b) 0.85% saline to drink for up to 14 days; controls were given water. (c) Water or saline followed by captopril/water or captopril/saline for 7 days. (d) In hypotensive mice only, 0.85% saline, 0.85% saline plus captopril, water or captopril in water. Systolic blood pressures (SBP) were measured by a computerized tail-cuff sphygmomanometer. Results were compared by analysis of variance (ANOVA). RESULTS: Captopril lowered SBP in all strains of mice. When saline was given with captopril, the fall in SBP was slower but the final SBP level was similar to that of mice given captopril in water. Hypotensive mice showed a transient rise in SBP on saline, which was abolished by concurrent treatment with captopril. CONCLUSION: Captopril lowers blood pressure in hypertensive, normotensive and hypotensive mice. Salt-loading retards the captopril-induced fall in SBP, but the final level of SBP achieved is similar to that in mice given captopril with water. The BPL1 strain of mouse was slightly salt-sensitive, and this was abolished by captopril.