Abstract
Summary
The effects ot two β-adrener-gic receptor-blocking agents, timolol and propranolol, on resting PRA and on the hydralazine-induced increase in PRA were studied in SHR and in two strains of normo-tensive rats [Wistar (NWR) and Sprague-Dawley (NSDR)]. With single oral doses, these β-adrenergic-blocking drugs reduced PRA in a dose-dependent manner in SHR but not in NWR or NSDR. After four daily doses, timolol antagonized the hydralazine-induced increase in PRA in SHR and lowered PRA in NWR. Timolol lowered PRA in NSDR only at 10 mg/kg/day p.o. for 4 days. It was concluded that SHR are more sensitive than normotensive rats to the PRA-lowering effects of β-adrenergic-blocking drugs.
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