Captopril potentiates the vasodepressor action of Met‐enkephalin in the anaesthetized rat

Open Access
Publisher Website
Google Scholar
Abstract
The transient vasodepressor action of Met‐enkephalin (10–80 μg kg−1, i.v.) in anaesthetized rats was significantly potentiated by the angiotensin‐converting enzyme inhibitor, captopril (2 mg kg−1, i.v.); at this dose, it failed to modify the transient vasodepressor action of the non‐specific vasodilator, nitroprusside (2.5, 5.0, 10 μg kg−1, i.v.). Captopril (2 mg kg−1, i.v.) caused a slow, progressive fall in the blood pressure of anaesthetized spontaneously hypertensive (SH) rats when compared to vehicle‐treated controls. Pretreatment with naloxone (1.5 mg kg−1, i.v.) 30 min earlier failed to alter significantly the hypotensive action of captopril in anaesthetized SH rats. It was concluded that although captopril potentiated the vasodepressor action of Met‐enkephalin in anaesthetized normotensive rats, potentiation of endogenous opioids does not appear to be involved in the hypotensive action of captopril in anaesthetized SH rats.