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Title: Vasoactive hormone studies in man using urotensin II and vasopressin
Author: Affolter, Jonathan Theodore
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2007
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Using the established method of bilateral venous occlusion plethysmography to measure forearm blood flow, combined with intra-arterial infusion of drugs into the brachial artery, we sought to determine the effects of urotensin II on human forearm blood flow. Other methods such as the Aellig venous displacement technique, to assess venous tone, and pulse wave analysis, to quantify arterial stiffness were also used during local and systemic urotensin II intravenous infusions respectively. Doppler flowmetry was used to assess skin microcirculation combined with intra-dermal peptide injection respectively. Doppler flowmetry was used to assess skin microcirculation combined with intra-dermal peptide injection; we assessed skin blood flow in response to vasopressin alone and in combination with a novel selective VI antagonist. Venous occlusion plethysmography was again used to determine forearm blood flow responses to vasopressin alone and in combination with V1 and V2 antagonists. During intra-arterial infusion of urotensin II we did not observe any significant changes in forearm blood flow, even in the presence of endothelial inhibitors such as aspirin and a ‘nitric oxide clamp’ nor was change observed in venous tone. Moreover, no alteration in systemic haemodynamics or arterial stiffness was seen during systemic intravenous infusion. We observed a significant fall in skin blood flow with intra-dermal injection of vasopressin, however, the V1 receptor antagonist did not alter skin vasoconstriction. Intra-arterial infusion of vasopressin caused a reproducible biphasic change in forearm blood flow, low doses causing vasoconstriction and high doses, nitric oxide mediated vasodilatation. Vasodilatation was subject to tachyphylaxis during prolonged infusion of high dose vasopressin. Neither intra-arterial V1 or V2 antagonist, when co-infused with vasopressin, altered this biphasic vasoconstriction and vasodilatation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available