Comparison O F Effects of Locally Infused Angiotensin I and I1 O N Hand Veins and Fore- Arm Arteries I N Man: Evidence for Converting Enzyme Activity I N Limb Vessels

It has been suggested that renin can generate angiotensin I1 at a local vascular level (Thurston & Swales, 1974). For this to occur, angiotensin converting enzyme must also be present. This enzyme occurs predominantly in the vascular bed of the lungs of animals (Vane, 1974), but it has also been shown to occur in the arterial bed of the hind limb of the dog (Aiken & Vane, 1972) and sheep (Osborn, Tildesley, O’Gorman & Mahler, 1971), the dog intestine (Di Salvo & Montefusco, 1971) and kidney (Aiken & Vane, 1972). In man, conversion of angiotensinI (AI) into angiotensin I1 (AII) has been shown to take place in the pulmonary vascular bed (Biron, Campeau & David, 1969), but it is not known if conversion can also take place at other sites. We have studied this problem by comparing the response of superficial hand veins and the forearm arterial bed to locally infused A1 and AII. We have also examined the effect on the venous response of an angiotensin converting enzyme inhibitor, the nonapeptide BPP,, or SQ 20,881 (Collier, Robinson & Vane, 1973).