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)

Previous studies of mice homozygous for one of several overlapping radiation-induced deletions in chromosome 7 revealed reduced expression of a number of hepatocyte proteins. These proteins include the plasma membrane receptors for insulin, epidermal growth factor, and glucagon, all of which are reduced in number by over 70% with no change in apparent affinity constants. It is not known whether all or only select liver cell surface proteins are so affected in newborn deletion homozygotes. In the present study, we investigated expression of two additional, functionally distinct intrinsic hepatocellular membrane binding proteins: the hepatic binding protein (HBP: the receptor for asialoglycoproteins), and the organic anion binding protein (OABP) which may play a role in organic anion transport. Immunoblot analysis showed the content of OABP and HBP in neonatal mutants to be identical to that in controls. As compared to adults, neonates showed levels of only about 8% of HBP and 75% of OABP binding proteins. Assays of HBP binding activities confirmed these results. The normal levels of these hepatocyte binding proteins in the deletion homozygotes suggest that the DNA sequences deleted in these mutants do not regulate all genes encoding such proteins but only a selected number of them.
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PMID:Selective expression of hepatocellular membrane proteins in mice homozygous for a lethal chromosomal deletion. 394 35

We evaluated the distribution and fate of homologous radioactive Hepatic-binding-protein (125I-HBP) in the rabbit after intravenous (iv) injection and the possibility that this protein may induce interferon production. We demonstrated that only 9% of the injected 125I-HBP remained in the circulation 30 min after injection. The 125I-HBP-Asialoorosomucoid complex displayed a longer half-life than the HBP alone, while 125I-Asialoorosomucoid had a very short half-life and only 1% of the dose was found in the circulation after iv administration. Ten min after iv injection of 125I-HBP the major amount of radioactivity was present in the liver and less in the kidneys and lung. HBP, after iv administration, does not stimulate interferon production and this fact is probably due to its rapid catabolism.
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PMID:Short circulatory residence of the hepatic binding protein. 620 22

To investigate the possible role of an alteration in excitation-contraction coupling in cardiac hypertrophy, we compared simultaneously recorded action potentials along with isometric or isotonic contractions of normal and hypertrophied papillary muscles. Hypertrophy was produced by renal hypertension in rats. Hypertrophied papillary muscles were taken from rats that had been hypertensive for 10 [HBP (10)] or 20 [HBP (20)] weeks. Regression of changes induced by hypertrophy was studied in rats that had been hypertensive for 10 weeks and then made normotensive for 10 weeks by removal of the ischemic kidney. Papillary muscles from age-matched, sham-operated rats [SHAM (10), SHAM (20)] were used as controls. We found that HBP (10) rats had significantly longer action potentials than SHAM (10) rats and that difference in the action potential duration recorded during isotonic and isometric contractions was significantly different from SHAM (10) and HBP (10) rats. Peak developed tension was the same in HBP (10) and SHAM (10) muscles, but the duration of isometric contraction and time-to-peak shortening were longer in HBP (10) muscles. Similarly, whereas the peak tension was the same in HBP (20) and SHAM (20) muscles, the duration of the action potential and isometric contraction, as well as the time-to-peak tension, was longer in HBP (20) muscles. The longer values for action potential duration, isometric contraction, and time-to-peak tension in HBP (20) muscles returned to SHAM values in HBP (R) muscles. The functional relationship between contraction and the action potential time course was assessed by plotting action potential duration against four parameters of contraction: peak developed tension, time-to-peak tension, time-to-half relaxation, and time-to-peak shortening. Statistical analysis of these data showed a significant correlation between action potential duration and all four parameters of contraction in SHAM (10) and SHAM (20) muscles. In contrast, HBP (10) muscles showed a significant correlation between action potential duration and only two contractile parameters, whereas action potential duration did not correlate significantly with any of the contractile parameters in HBP (20) muscles. Remarkably, in HBP (R) preparations a significant correlation was restored between action potential duration and three of the four contractile parameters. The results of this study suggest that reversible cardiac hypertrophy is associated with reversible alterations in excitation-contraction coupling. The reversibility of the mechanical and electrical alterations that accompany hypertrophy suggests, in turn, that cardiac hypertrophy is an adaptive process.
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PMID:Reversible alterations in excitation-contraction coupling during myocardial hypertrophy in rat papillary muscle. 621 59

A 93,000 molecular weight protein (HBP.93) which binds hemin and protoporphyrin IX with high affinity has been isolated from rabbit serum using affinity chromatography on hemin-conjugated agarose. The amino acid composition of this protein is unique in that the proline and histidine contents are remarkably high (16.6 and 9.9 mol %, respectively). A large increase in the absorbance of the Soret region arises from the heme-protein interaction. The spectrophotometric titration showed that the protein can bind 25-35 mol of hemin/mol of protein. The apparent dissociation constant was estimated to be 1-4 X 10(-7) M for hemin at pH 7.4 and approximately 10(-6) M for protoporphyrin IX at pH 9.2. The similarity of the difference spectrum of heme-HBP.93 complex to that of heme-hemopexin complex suggests that a bisimidazol-type coordination of heme iron is involved in the binding. The extremely high capacity of HBP.93 to bind heme is also demonstrated by a large increase in the sedimentation velocity of the protein upon heme binding. The native heme-protein complex migrates faster than the heme-free protein in a polyacrylamide gel at pH 8.8; the increased mobility appears to be due to the charge on the carboxyl groups of the bound heme. Although the use of a hemin-agarose column has failed to reveal a protein of similar size and heme affinity in the sera of a number of other species, including man, the heme-binding properties and high histidine level of the human alpha 2-histidine-rich glycoprotein raise the possibility that the two proteins are related.
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PMID:A protein with multiple heme-binding sites from rabbit serum. 627 54

The radioiodinated pindolol analogs 125I-labeled cyanopindolol ([125I]CYP) and 125I-labeled hydroxybenzylpindolol ([125I]HBP) have been used to study binding to human platelet beta-adrenergic receptors. [125I]CYP binds to a saturable class of binding sites on platelet membranes with a dissociation constant (Kd) of 14 +/- 3 pM and maximal binding capacity (Bmax) of 18 +/- 4 fmol/mg protein. Binding of [125I]CYP is reversible and is characterized by forward and reverse rate constants of 1.8 . 10(7) s-1 . M-1 and 3.8 . 10(-4) s-1, respectively. [125I]HBP binds to a saturable class of platelet membrane sites with a Kd of 50 +/- 10 pM and Bmax of 32 +/- 6 fmol/mg protein. [125I]HBP also binds to a saturable class of sites on intact platelets with a Kd of 58 +/- 14 pM and Bmax of 24 +/- 4 molecules per platelet. Binding of [125I]CYP and [125I]HBP is stereospecifically inhibited by propranolol and epinephrine; the (-) stereoisomers are at least 50-times more potent than the (+) stereoisomers. Binding of both radioligands is inhibited by adrenergic ligands with a potency order of propranolol much greater than isoproterenol greater than epinephrine greater than practolol greater than norepinephrine greater than phenylephrine. These observations indicate that [125I]CYP and [125I]HBP bind to platelet sites which have the pharmacological characteristics of beta-adrenergic receptors but which are not typical of either the beta 1 or beta 2 sub-type.
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PMID:Demonstration of human platelet beta-adrenergic receptors using 125I-labeled cyanopindolol and 125I-labeled hydroxybenzylpindolol. 628 27

Hemin, in the presence of 2-mercaptoethanol and oxygen, catalyzes the selective degradation of heme-binding proteins to small peptide fragments. Among the proteins examined, the heme-binding protein of rabbit serum (HBP-93) proved to be unusually sensitive. Myoglobin also exhibited considerable sensitivity whereas hemopexin and bovine serum albumin were only slightly susceptible to this degradative action of hemin. The reaction with HBP-93 depended upon coordination of the protein with hemin, was optimal at pH 6.5 and increased 4-fold as the temperature was elevated from 10 to 60 degrees C. The requirement for both oxygen and the reducing agent, 2-mercaptoethanol, and the partial protection of HBP-93 to degradation by catalase, superoxide dismutase, mannitol, and thiourea suggest the involvement of reduced oxygen species in the reaction. A possible role for the heme-mediated degradation of proteins in cell differentiation and other biological responses is discussed.
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PMID:Hemin-mediated oxidative degradation of proteins. 632 3

We investigated the renin-angiotensin system in the genetically hypertensive (HBP), normotensive (NBP) and low blood pressure (LBP) mice developed by G. Schlager, one of the authors. Renin in the plasma, kidney and submaxillary gland was determined by enzymatic assay and by direct radioimmunoassay (DRIA). Trypsinization of mouse plasma was also investigated. PRA and plasma renin content were not significantly different in the different lines, sexes and generations. Trypsinization of the plasma revealed the presence of inactive renin, as has also been found in humans, hogs, dogs and rats. The proportion of active renin against trypsinized total renin was about 54-77% and was not significant in the different lines, sexes and generations. There was also no significant difference in renal renin content in the various lines, sexes and generations. However, in the submaxillary gland, renin content and activity were high in male mice, in every line. These data suggest that the renin-angiotensin system may not contribute to the established phase of blood pressure.
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PMID:Renin-angiotensin system in genetically hypertensive mice. 638 22

It was found that autoxidative degradation is responsible for the inactivation of the unstable Microcystis toxin HBP-Tx. The purified toxin was similar in its properties to the "fast-death-factor" in Microcystis, described as a cyclic peptide in the literature. The apparent presence of an entirely different toxin was simulated by the partially inactivated HBP-Tx. A number of associated fluorescent compounds were identified as the non-toxic degradation products of the toxin. As a consequence, as established method for the detection of other algal toxins was applied. This chemical assay, which uses fluorescent measurement of the oxidized toxin in the cyanobacterium Aphanizomenon flos-aquae, was applicable for HBP-Tx after the removal of interfering degradation products of the toxin. The results obtained with Microcystis toxin HBP-Tx do not confirm suggestions concerning the structure of the "fast-death-factor".
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PMID:Instability and variable toxicity of HBP-Tx, a toxin in the cyanobacterium Microcystis aeruginosa. 642 92

We studied the distribution and nature of the electrical changes associated with myocardial hypertrophy induced by renal hypertension in rats. Standard microelectrode techniques were used to study transmembrane action potentials recorded from endocardial, papillary muscle, and epicardial stimulation from hypertrophied (HBP) and normal (SHAM) hearts. We also determined the effects of stimulation frequency on the action potentials recorded from these preparations. To assess whether altered intercellular electrical connections contribute to the electrophysiological changes associated with hypertrophy, we analyzed the spatial steady state voltage decrement produced by passing intracellular constant current pulses and determined the effective input resistance (Rin) of endocardial HBP and SHAM preparations. Our results show that the action potential prolongation that accompanies hypertrophy is not uniform. Thus, the entire course of repolarization is prolonged in epicardial and papillary muscle fibers, but only the latter half of repolarization is prolonged in epicardial fibers. Endocardial action potentials is general, and HBP action potentials in particular, have a distinctive steep relation between duration and stimulation frequency which may be due to a difference in the rate dependence of a membrane conductance(s), although relatively greater accumulation of extracellular potassium or altered activity of the Na+-K+ pump cannot be excluded as contributing factors. In addition, the similarity in the profile of spatial voltage decrement and the values for Rin in HBP and SHAM preparations indicates that alterations in electrotonic coupling between cells are unlikely to account for the prolonged action potentials of hypertrophied myocardium.
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PMID:Non-uniform electrophysiological properties and electrotonic interaction in hypertrophied rat myocardium. 645 68

The results of previous studies of the relation between the surface electrocardiogram and cellular transmembrane potentials have suggested that the T wave configuration of the ECG is the result of a difference in the duration of endocardial and epicardial action potentials. Ventricular hypertrophy induced by renal hypertension in rats is associated with lengthening of action potential duration and a reproducible decrease in T wave magnitude. Therefore, this model was used to study the relation between the surface T wave configuration and regional differences in action potential duration. ECGs were recorded from hypertensive (HBP) and sham-operated (SHAM) rats. The hearts from these animals were removed and transmembrane action potentials were recorded by standard microelectrode techniques from endocardial and epicardial preparations. We found that the normally peaked T waves seen in the ECG of SHAM rats was reduced by 35% in the ECG of HBP rats. This reduction of T wave magnitude was associated with similar duration of epicardial and endocardial action potentials in HBP rats. However, peaked T wave in SHAM ECG was not accompanied by a significant disparity in the duration of the epicardial and endocardial action potentials. Thus, there is no simple, consistent correlation between surface T wave configuration and regional differences in intracellular action potential duration in rats.
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PMID:Transmembrane action potentials and the electrocardiogram in rats with renal hypertension. 645 47


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