Changes in tissues and general renin-angiotensin system’s function are
   the most important factors in cardiovascular disease such as essential
   hypertension. Recent research shows that general  renin - angiotensin 
   system  affects the short and immediate response , and that of the tissues
   systems are effective in long  period functions in controlling cardiovascular
   mechanism . This study was carried out to investigat the changes in function
   of tissue renin - angiotensin  systems in mesenteric resistance vessels of
   Goldblatt tow kidney – one clip ( 2k - 1c ) renovascular hypertensive rats.

          Vascular response to angiotensin I and captopril effects were observed
   during a period of 2, 4 , 6 and 8 weeks post  hypertension  induction. The
   blood pressure of the hypertensive group was measured and compared
   with both sham and control groups.

          This study showed that after eight weeks of hypertension induction ,
   captopril was unable to inhibit converting  angiotensin I to angiotensin II .
   These changes were synchronous  with precipitate process of  increased
   arterial blood pressure in hypertensive animals.

          This was probably due to increased  angiotensin  converting enzyme
   activity or production of other enzymes , such as Chymase that , introduced 
   a role in angiotensin  II  production . More investigation and accurate study
   of the process can probably affect to recognize the ethiology  and efficient
   treatment of  hypertension and other  cardiovascular disease .