angiotensin-iii and Hypotension

Components of the renin angiotensin system, namely renin, angiotensinogen, angiotensin I and II and aldosterone were measured in plasma of patients with hymenoptera venom anaphylaxis (n = 50) and healthy non-allergic controls (n = 25). Patients with a history of anaphylactic reactions to hymenoptera venom who did not undergo immunotherapy showed significantly reduced renin, angiotensinogen, angiotensin I and angiotensin II in plasma as compared with controls (P < 0.05). There was no difference in the aldosterone concentration between patients and controls. Angiotensin I, angiotensin II, renin and angiotensinogen levels were the same in male and female patients. There was also no difference in the angiotensin I, II, renin or angiotensinogen levels between young and older patients. A significant inverse correlation between the severity of clinical symptoms and the plasma levels of renin (r = -0.382, P < 0.001), angiotensinogen (r = -0.567, P < 0.0001), angiotensin I (r = -0.656, P < 0.0001) and angiotensin II (r = 0.0762, P < 0.0001) was found: the lower the levels the more severe the clinical symptoms. No correlation was found for aldosterone. Hymenoptera venom allergic patients with repeated anaphylactic reactions during hyposensitization did not tolerate the sting of a living insect (n = 6). In these patients, renin, angiotensinogen, angiotensin I and II remained significantly lower than in healthy non-allergic controls. Patients with successful immunotherapy (n = 27) who tolerated the sting of a living insect had renin, angiotensin I and II significantly higher than patients without immunotherapy. These findings suggest a possible role of the renin angiotensin system in hymenoptera venom anaphylaxis.

Topics: Adolescent; Adult; Aged; Aldosterone; Anaphylaxis; Angiotensin I; Angiotensin II; Angiotensin III; Angiotensinogen; Bee Venoms; Child; Desensitization, Immunologic; Female; Homeostasis; Humans; Hypotension; Male; Middle Aged; Renin; Renin-Angiotensin System; Severity of Illness Index; Wasp Venoms

This study was designed to ascertain whether renal vascular angiotensin receptors differ from other systemic angiotensin receptors and whether, on that basis, antagonists with greater specificity for the renal vasculature can be defined. Femoral and renal blood flow and their responses to angiotensin II (AII) and its heptapeptide analogue, 1-des Asp AII (AIII), were measured with an electromagnetic flowmeter in 26 dogs. For the kidney, the threshold doses of AII and AIII were identical (2.5+/-0.27 vs. 2.3+/-0.35 pmol/100 ml renal blood flow, with similar dose-response curves. In contrast, AII had a greater pressor effect (P less than 0.001) and produced more femoral vasoconstriction (P less than 0.001) than AIII. All four antagonists studied (1-Sar, 8-Ala AII [P113]; 8-Ala AII; 1-des Asp, 8-Ala AII; 1-des Asp, 8-Ile AII) induced parallel shifts in the renal blood flow response to AII and AIII. P113 induced greater blockade than 8-Ala AII (P less than 0.001) which, in turn, was more effective than 1-des Asp, 8-Ala AII (P less than 0.001). 1-des Asp, 8-Ile AII was as effective as P113. Each analogue induced an identical inhibition of the renal vascular response to AII and AIII. In addition, AII and AIII induced cross-tachyphylaxis. All lines of evidence suggested that AII and AIII act on a single receptor in the kidney, which differs at least functionally from other systemic vascular receptors. The possibility that heptapeptide analogues represent angiotensin antagonists with greater specificity for the renal vasculature was pursued in a model in which the renin-angiotensin system is activated. Acute, partial thoracic inferior vena caval occlusion was induced in an additional 16 dogs. P113 induced progressive, dose-related hypotension and a limited increase in renal blood flow in this model. The 1-des Asp, 8-Ile AII analogue, conversely, induced a consistent, larger, dose-related renal blood flow increase, with significantly less hypotension over a wide dose range. We conclude that the renal vascular receptor differs sufficiently from systemic angiotensin receptors that heptapeptide analogues of AII will be useful in exploring angiotensin's role in states characterized by disordered renal perfusion and function.

Topics: Angiotensin II; Angiotensin III; Angiotensin Receptor Antagonists; Animals; Blood Pressure; Constriction; Dogs; Dose-Response Relationship, Drug; Femoral Artery; Hypotension; Kidney; Receptors, Angiotensin; Receptors, Cell Surface; Regional Blood Flow; Vena Cava, Inferior