AIM To establish a new bioassay method for estimating the rat
Angiotensin ⅰ Converting Engyme (Ace)', 1, 1608626)"; href="/tags/angiotensin-%E2%85%B0-converting-engyme-(ace)/" onclick="javascript:LinkToPage('','link_id=110')">
Angiotensin ⅰ Converting Engyme (Ace) activity in vivo
by using ramipril (Ram), a ACE inhibitor. METHODS The change in mean arterial pressure induced by angioteuasin Ⅰ (AngⅠ) or bradykinin (BK) was measured before and 1, 24, 48 h after pretreatment with Ram (0 05,0 1 mg·kg -1 ,iv). The ACE activity was expressed by the pressor effect (%)of AngⅠ or the depressor effect (%) of BK. RESULTS The pressor effects of AngⅠ or the supernatant fraction of heart tissue homogenate containing AngⅠ were siginificantly reduced 1 h and 24 h after pretreatment with Ram, but not 48 h after pretreatment with Ram. In comparison of the depressor response of BK vs pressor response of AngⅠ 1 h after pretreatment with Ram,it was shown that the depressor effect of BK is more sensitive than the pressor effect of AngⅠ( P <0 05). CONCLUSIONS Ram maintains inhibitory effect to ACE in the plasma or myocardial tissues within 24 h in dose dependent manner. But the inhibition disappeares by 48 h. As a parameter of ACE inhibition,the BK induced depressor effect is more sensitive than the pressor effect of AngⅠ.