Hypertension
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The acute administration of the angiotensin-converting enzyme (ACE) inhibitor captopril to healthy subjects transiently increases 5.5-fold the plasma levels of a natural stem-cell regulator, N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP). The aim of this study was to measure plasma Ac-SDKP levels during chronic treatment with all types of ACE inhibitors and to assess its relevance as a marker of ACE inhibition. Plasma levels of Ac-SDKP were blindly determined in age- and sex-matched hypertensive patients either treated (ACEI group, n=27) or not (non-ACEI group, n=23) with an ACE inhibitor for more than 1 month. ⋯ We conclude that Ac-SDKP accumulates in plasma during chronic ACE inhibitor treatment. The long-term consequences of Ac-SDKP accumulation are unknown. The reliability of plasma Ac-SDKP measurement makes it the best marker of chronic ACE inhibition, which can help to verify patients' compliance to ACE inhibitor treatment.
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Randomized Controlled Trial Clinical Trial
Effects of SR 49059, a new orally active and specific vasopressin V1 receptor antagonist, on vasopressin-induced vasoconstriction in humans.
We have evaluated the efficacy of SR 49059, a new orally active and specific vasopressin V1 receptor antagonist (arginine-vasopressin [AVP]), in the blockade of the vascular effects of exogenous AVP in healthy subjects. In preliminary experiments, two procedures to measure the V1 vascular effects of AVP were assessed. First, the AVP-induced changes in skin blood flow were investigated by the injection of increasing doses of AVP intradermally, with or without a previous local vasodilation with calcitonin gene-related peptide (CGRP). ⋯ In addition, the 300-mg dose of SR 49059 completely blocked the vasoconstriction of the radial artery induced by AVP. In conclusion, skin blood-flow measurement, after intradermal injection of AVP on a skin area vasodilated with CGRP, is an effective method to investigate the V1 vascular effect of AVP in humans. SR 49059 is a potent and specific antagonist of V1 receptors, which blocks the AVP-induced vasoconstriction.
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The effects of the nonpeptide angiotensin II AT1 receptor antagonist candesartan on responses to angiotensin II were investigated in the mesenteric vascular bed of the cat. Under constant-flow conditions, injections of angiotensin II caused dose-related increases in perfusion pressure that were reduced by candesartan in doses of 3, 10, and 30 microg/kg i.v.. After administration of the AT1 receptor antagonist in a dose of 3 microg/kg i.v., the dose-response curve for angiotensin II was shifted to the right in a parallel manner, whereas the administration of higher doses resulted in nonparallel rightward shifts of the angiotensin II dose-response curves. ⋯ Treatment with the AT2 receptor antagonist PD123,319 or with sodium meclofenamate did not alter the inhibitory effects of candesartan on responses to angiotensin II. Candesartan also decreased pressor responses to angiotensin III and IV with a parallel shift at the low dose and a nonparallel shift to the right of the dose-response curve at the high dose. These results indicate that candesartan is a potent, selective, long-acting AT1 receptor antagonist that, depending on dose, can produce both competitive and noncompetitive blockade of responses to angiotensin II, III, and IV.