THE ROLE OF ANGIOTENSIN-CONVERTING ENZYME AND NITRIC-OXIDE IN THE ENHANCED SYSTEMIC DEPRESSOR RESPONSES TO BRADYKININ IN PREGNANT RATS

1. In the present study we have examined the effects of angiotensin I converting enzyme (ACE) inhibition and nitric oxide (NO) synthesis inh ibition on bradykinin (BK) depressor responses in pregnancy in both Wi star-Kyoto (WKY) and spontaneously hypertensive rats (SHR). 2. Ramipri l (10 mg/kg, i.v.) significantly reduced mean blood pressure (MBP) in all animals, Further administration of L-nitro-arginine (L-NOARG, 20 m g/kg, i.v.) increased MBP to a less extent in pregnant WKY and to a si milar level in pregnant SHR compared with their non-pregnant controls (controls), respectively. 3. Systemic depressor responses to BK were i ncreased in pregnant WKY and were unchanged in pregnant SHR as compare d with their controls. Ramipril (10 mg/kg, i.v.) potentiated BK respon ses in all groups, and abolished the differences between pregnant and non-pregnant WKY. Further administration of L-NOARG (20 mg/kg, i.v.) d id not further influence BK responses in all groups. 4. The results su ggest that systemic depressor responses to BK are enhanced in pregnant WKY and unchanged in pregnant SHR. Decreased ACE activity may contrib ute to enhanced systemic depressor responses to BK in pregnant WKY.