Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent studies have suggested that the angiotensin II (ANG II) metabolite [Des-Asp]ANG II (ANG III) may be nearly equipotent with the parent compound in causing several acute neural responses known to be stimulated by angiotensin peptides (i.e., drinking, augmentation of sympathetic neurotransmission, and centrally mediated pressor responses). Because neural actions of ANG II are thought to contribute importantly to the ability of this hormone to cause chronic hypertension, the purpose of the present experiments was to explore the cardiovascular effects of chronic administration of ANG III either into the bloodstream or directly into the brain via the cerebral ventricles. The neurogenic component of the pressor response to acute infusion of ANG III also was reinvestigated. In anesthetized pithed rats (n = 6) ANG III had only 10% of the pressor potency of ANG II when given by acute (5-10 min) intravenous infusion. In conscious rats (n = 5) ANG III had 25% of the pressor potency of ANG II when tested using acute intravenous administration. The acute intravenous pressor potency ratio in conscious versus pithed rats was 4.8 for ANG III and 1.1 for ANG II, suggesting that, compared with ANG II, the pressor response to ANG III shows a greater dependence on neurogenic mechanisms at the doses tested. Chronic (5-day) intravenous infusion of ANG III (at 10, 20, and 100 ng/min) caused sustained hypertension without changes in fluid/electrolyte balance, but only at a dose (100 ng/min) estimated to produce blood levels of ANG III well beyond the "physiological" range.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hypertension during chronic peripheral and central infusion of angiotensin III. 402 41

Rabbit brain endo-oligopeptidase B inactivates angiotensin I (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu) and angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) by hydrolysis of the Pro7-Phe8 peptide bond. The site of hydrolysis was determined in preparative and analytical experiments in which both products were recovered in a molar ratio of 1:1, and the sum of the products plus unhydrolyzed substrate accounted for the starting material. The enzyme has a Km of 6.3 x 10(-5) M for angiotensin II at pH 8.3 and is activated 30-fold with 4.8 mM dithiothreitol. BPP9a ( less than Gln-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro, SQ 20,881) inhibits the inactivation of angiotensin II with an I50 of 5 x 10(-5) M. BPP5a (less than Gln-Lys-Trp-Ala-Pro, SQ 20,475) is less active and D-3-mercapto-2-methylpropanoyl-L-proline (captopril, SQ 14,225) has essentially no activity. These endo-oligopeptidase B in angiotensin I and II metabolism remains to be established.
Hypertension
PMID:Brain endo-oligopeptidase B: a post-proline cleaving enzyme that inactivates angiotensin I and II. 617 71

The effects of captopril (SQ 14.225), an orally active inhibitor of angiotensin converting enzyme, were investigated in a dose titration study of primary hypertension. In 32 patients 4 weeks titration with captopril gave a mean blood pressure (BP) reduction of 26/16 mmHg supine and 30/16 mmHg standing. No serious side effects were observed. The BP lowering effect was related to pretreatment plasma renin activity and was less in low renin hypertension (p less than 0.05). Captopril reduced angiotensin II (p less than 0.05), plasma (p less than 0.005) and urinary aldosterone (p less than 0.001) as well as urinary kallikrein excretion (p less than 0.005). Captopril (SQ 14.225) is a competitive inhibitor of peptidyl dipeptide hydrolase, also known as angiotensin converting enzyme (ACE) or kininase II, which converts angiotensin I (A I) into angiotensin II (A II), hydrolyzes des-Asp-angiotensin I to angiotensin III (A III) and inactivates bradykinin (BK) (19). Captopril has potent antihypertensive effects when used in human hypertension (review, 3) especially when the renin-angiotensin-aldosterone system (RAAS) is activated. To further investigate the mode of action and the hypotensive effect of captopril, we measured plasma renin activity (PRA), A II, plasma (PA) and urinary aldosterone excretion (UA) and urinary kallikrein excretion (UK) in 32 patients with established primary (essential) hypertension.
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PMID:Captopril in primary hypertension. Effects related to the renin-angiotensin-aldosterone and kallikrein-kinin systems. 701 90

The aspartic proteinases are an important family of enzymes associated with several pathological conditions such as hypertension (renin), gastric ulcers (pepsin), neoplastic disease (cathepsins D and E), and AIDS (HIV proteinase). Studies of inhibitor binding are therefore of great importance for design of novel inhibitors for potential therapeutic applications. Numerous X-ray analyses have shown that transition-state isostere inhibitors of aspartic proteinases bind in similar extended conformations in the active-site cleft of the target enzyme. Upon comparison of 21 endothiapepsin inhibitor complexes, the hydrogen bond lengths were found to be shortest where the isostere (P1-P'1) interacts with the enzyme's catalytic aspartate pair. Hydrogen bonds with good geometry also occur at P'2, and more so at P3, where a conserved water molecule is involved in the interactions. Weaker interactions also occur at P2, where the side-chain conformations of the inhibitors appear to be more variable than at the more tightly held positions. At P2 and, to a lesser extent, P3, the side-chain conformations depend intriguingly on interactions with spatially adjacent side chains, namely P'1 and P1, respectively. The tight binding at P1-P'1, P3, and P'2 is also reflected in the larger number of van der Waals contacts and the large decreases in solvent-accessible area at these positions, as well as their low temperature factors. Our analysis substantiates earlier proposals for the locations of protons in the transition-state complex. Aspartate 32 is probably ionized in the complexes, its charge being stabilized by 1, or sometimes 2, hydrogen bonds from the transition-state analogues at P1. The detailed comparison also indicates that the P1 and P2 residues of substrate in the ES complex may be strained by the extensive binding interactions at P3, P'1, and P'2 in a manner that would facilitate hydrolysis of the scissile peptide bond.
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PMID:A structural comparison of 21 inhibitor complexes of the aspartic proteinase from Endothia parasitica. 770 59

The conversion of 11-deoxycorticosterone (DOC) to aldosterone is catalyzed by a single enzyme, termed P450c11AS, which has 11 beta-hydroxylase, 18-hydroxylase and 18-oxidase activities. The normotensive Dahl salt-resistant (R) rat has two mutation in P450c11AS that increase its aldosterone synthase activity. If such a mutation were to occur in human patients the predicted phenotype would be low-renin hypertension with elevated ratios of plasma aldosterone to plasma renin activity. Before searching for P450c11AS mutations in such patients we sought to determine if mutations in human P450c11AS could increase enzymatic activity in a fashion analogous to the Dahl R rat. We used site-directed mutagenesis of the human P450c11AS cDNA to create the mutants Glu 136-->Asp, Lys 251-->Arg and the combination of the two; these mutations correspond to those seen in the Dahl R rat. Cells transfected with these mutant human P450c11AS sequences could convert [14C]DOC to corticosterone, 18OH-corticosterone, and aldosterone. In particular the Lys 251-->Arg mutant produced 4 times as much 18OH-corticosterone and 50-80% more aldosterone than the wild type. These data show that mutations of human P450c11AS can increase enzymatic activity, suggesting that such mutations could, in theory, be the basis of some forms of human low-renin hypertension.
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PMID:Artificial mutations in P450c11AS (aldosterone synthase) can increase enzymatic activity: a model for low-renin hypertension? 788 20

We determined the antihypertensive effects of BQ-123 (cyclo(D-Trp-D-Asp-L-Pro-D-Val-L-Leu-), sodium salt), a selective endothelin ETA receptor antagonist, in spontaneously hypertensive rats treated with deoxycorticosterone acetate-salt (DOCA-salt SHR). BQ-123 (1-30 mg/kg/h) decreased blood pressure in DOCA-salt SHR in a dose-dependent manner, although plasma immunoreactive endothelin-1 did not significantly increase and the maximal contractile response to endothelin-1 in the aorta significantly decreased as compared with values observed in age-matched SHR. These results suggest that endogenous endothelin-1 is involved in the maintenance of hypertension in DOCA-salt SHR, and that circulating endothelin-1 is not sufficient to reflect the physiological role of endothelin-1.
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PMID:Antihypertensive effects of BQ-123, a selective endothelin ETA receptor antagonist, in spontaneously hypertensive rats treated with DOCA-salt. 798 65

The renin-angiotensin system (RAS) is the most important regulator of electrolyte homeostasis and blood pressure. Our recently generated transgenic mice carrying either the human renin (hREN) or human angiotensinogen (hANG) genes did not develop hypertension but dual gene strains obtained by cross-mating separate lines of mice exhibited a chronically sustained increase in blood pressure, suggesting the presence of species-specific reactivity between renin and angiotensinogen. In order to examine this specificity, the present study was designed to perform a strictly comparative study on hydrolysis of hANG by hREN and mouse submandibular renin (mREN) in vitro by using pure proteins. The recombinant hANG (rhANG) and the synthetic human-type tridecapeptide (hTDP), Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu-Val-Ile-His, corresponding to the N-terminal sequences of hANG, were used to determine the species specificity of recombinant hREN (rhREN) and mREN. While hTDP was cleaved by both rhREN and mREN with similar Km and with the same order of kcat, rhANG was cleaved by mREN with 16.7-fold higher Km and with 28.2-fold lower kcat than by rhREN. These results showed that kcat/Km value of mREN for rhANG was 468-fold lower than that for rhREN acting on rhANG.
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PMID:Comparative studies on species-specific reactivity between renin and angiotensinogen. 804 64

17 alpha-Hydroxylase deficiency blocks the biosynthesis of cortisol and sex steroids, resulting in mineralocorticoid excess, hypertension, sexual infantilism, and female phenotype in both genetic sexes. The disease is caused by mutations in the gene encoding cytochrome P450c17, which is the single enzyme that mediates both 17 alpha-hydroxylase and 17,20-lyase activities. We report a 14-yr-old patient from Thailand with a classical clinical presentation of this rare disorder. Analysis of her P450c17 gene by polymerase chain reaction amplification and sequencing showed a nine-base deletion, eliminating codons 487-489 (Asp-Ser-Phe) near the carboxy-terminus of P450c17. This deletion creates a BclI site in the mutant DNA, permitting accurate demonstration that the patient was homozygous for this lesion, whereas one parent and two siblings were heterozygous. By use of site-directed mutagenesis, we created a vector that could express this mutated form of P450c17 when transfected into non-steroidogenic COS-1 cells. Such transfected cells produced immunodetectable P450c17 protein, but had no 17 alpha-hydroxylase or 17,20-lyase activity, whereas cells similarly transfected with a vector expressing normal human P450c17 could 17 alpha-hydroxylate either pregnenolone or progesterone and convert 17 alpha-hydroxypregnenolone to dehydroepiandrosterone, showing the presence of both activities. This is the first report of the molecular genetic basis of 17 alpha-hydroxylase deficiency in a Southeast Asian patient.
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PMID:Deletion of amino acids Asp487-Ser488-Phe489 in human cytochrome P450c17 causes severe 17 alpha-hydroxylase deficiency. 834 56

The effects of the endothelin receptor antagonist TAK-044 (cyclo[D-alpha-aspartyl-3-[(4-phenylpiperazin-1-yl)carbonyl]-L-ala nyl-L-alpha-aspartyl-D-2-(2-thienyl)glycyl-L-leucyl-D-tryptophyl]+ ++disodiu m salt) and BQ-123 (cyclo[D-Asp-Pro-D-Val-Leu-D-Trp]) were studied in the rat heart to characterize the receptor subtypes responsible for the cardiovascular actions of endothelin-1. Endothelin-1 induced a transient decrease and subsequent increase in perfusion pressure in perfused rat hearts, and increased left ventricular developed pressure. TAK-044 diminished these endothelin-1-induced responses (100 pmol/heart) with IC50 values of 140, 57 and 1.3 nM, respectively. BQ-123 (1-30 mu M) partially inhibited the endothelin-1-induced hypertension (30-40%) in the rat heart, and failed to inhibit the hypotension. The positive inotropic effect of endothelin-1 was abolished by BQ-123. Neither indomethacin (10 mu M) nor Nomega-nitro-L-arginine methyl ester (100 mu M) attenuated the endothelin-1-induced hypotension. TAK-044 and BQ-123 attenuated the positive inotropic effect of endothelin-1 in rat papillary muscles. In rat cardiac membrane fractions, TAK-044 and BQ-123 inhibited [125I]endothelin-1 binding to endothelin ET(A) receptors with IC50 values of 0.39 +/- 0.6 and 36 +/- 9 nM, respectively, whereas only TAK-044 potently blocked the endothelin ET(B) receptor subtype (IC50 value: 370 +/- 180 nM). These results suggest that endothelin-1 modulates cardiovascular functions in the rat heart by activating both endothelin ET(A) and endothelin ET(B) receptors, all of which are sensitive to TAK-044.
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PMID:Pharmacological characterization of cardiovascular responses induced by endothelin-1 in the perfused rat heart. 872 Apr 78

We examined the apolipoprotein E polymorphism of an obese patient presenting non-insulin-dependent diabetes, hypertension and moderate lipid disturbances. The apolipoprotein E genotyping carried out from leukocyte DNA using PCR amplification and restriction enzyme digestion demonstrated homozygosity for the rare apoE1[Gly127-->Asp; Arg158--> Cys] (Weisgraber allele). The nucleotide change results in a glycine to aspartic acid substitution at amino acid 127 in the apolipoprotein E2.
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PMID:Genotyping of a patient homozygous for a rare apolipoprotein E1 [Gly127-->Asp; Arg158-->Cys] (Weisgraber allele). 875 Jun 11


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