A comparative study of tumour-blood-flow modification in two rat-tumour systems using endothelin-1 and angiotensin II: Influence of tumour size on angiotensin-II response
✍ Scribed by Katrina M. Bell; Vivien E. Prise; Katija M. Shaffi; David J. Chaplin; Gillian M. Tozer
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- French
- Weight
- 1003 KB
- Volume
- 67
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
Tumour blood flow modification following i.v. administration of angiotensin II (AT II, 0.19 nmol kg-' min-I) or endothelin-I (ET-I, I nmol kg-') was compared in the P22 carcinosarcomabearing BD9 rat and the HSN fibrosarcoma-bearing CBH/CBi rat using the tissue uptake of radiolabelled iodoantipyrine. Results were compared with a range of normal tissues. HSN tumour blood flow was Unmodified by either peptide, whereas P22 tumour blood flow was unmodified by ET-I but was reduced to 80% of the control flow by AT II. Both peptides reduced absolute blood flow in the skin overlying the tumour, in contralateral skin, skeletal muscle, kidney and small intestine, whereas blood flow to the brain and heart was significantly increased by ET-I and unmodified by AT II. Both peptides significantly increased vascular resistance (mean arterial blood pressure + tissue blood flow) in all normal tissues and both turnours, thus demonstrating the existence of vascular receptors for these 2 vasomodifiers, and the capacity of the vessels to respond to receptor activation. Dependency of response on tumour size was examined in the P22 tumour. In contrast to that in small P22 tumours (I .22 f 0.06 g), blood flow to large P22 tumours (7. I8 f 0.25 g) was unmodified by AT II. Vascular resistance was equally increased in both tumour groups, thus illustrating little difference in the vascular response to AT II in the size range examined. Results show that the 2 rat tumours responded directly to ET-I and AT II, but do not indicate any advantage of ET-I over AT II in tumour blood flow modification.