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Biomedical subjects

T Inagami

Publications and source records attributed to T Inagami.

At least 379 records · Page 21Linked to original sources
PubMed1984

Kallikrein-kinin and renin-angiotensin systems in rat renal lymph.

Rat renal lymph contains 254 +/- 17 ng/ml (means +/- SEM, N = 20) of immunoreactive glandular kallikrein. Like the immunoreactive glandular kallikrein in plasma, it is biologically inactive. Gel filtration of renal lymph reveals profiles for immunoreactive glandular kallikrein, protein, and inhibition of trypsin and kallikrein which resemble those seen for plasma except that high molecular weight plasma components are reduced or missing in renal lymph. In contrast, gel filtration of thoracic lymph reveals immunoreactive glandular kallikrein and protein profiles which are indistinguishable from those seen with plasma. Renin levels are 170-fold higher in renal lymph than in thoracic lymph while angiotensin-converting enzyme levels are only 16% those of thoracic lymph. In keeping with the high renin and low converting enzyme activities, renal lymph contains high levels of angiotensin I. Immunoreactive glandular kallikrein levels in renal lymph, thoracic lymph and plasma do not show the striking differences observed for renin.

Angiotensin I↗
PubMed1984

Biochemistry of renin.

Biochemical features of renin have been studied. Determination of the amino acid sequence and catalytically essential groups in the active sites of mouse submandibular gland revealed the similarity of renin with acid proteases. Yet stringent substrate specificity, neutral pH optimum of its enzyme activity and the unique structure of the activation peptide distinguish it from digestive enzymes. Inactive renin was identified as renin zymogen by complete purification and translation in vitro.

Amino Acid Sequence↗
PubMed1984

Release of active and inactive renin from hog renal cortical slices in vitro.

Both inactive and active renin were released from renal cortical slices of the hog. Isoproterenol, prostaglandin E1, and dibutyryl cAMP stimulated the release of both inactive and active renin. Renal kallikrein caused selective stimulation of the release of active renin and suppressed the release of inactive renin. Bradykinin and kallidin did not stimulate renin release. The effect of kallikrein was abolished by aprotinin but not by indomethacin. These observations indicate that the effect of kallikrein is not mediated via kinin formation or prostaglandin generation. The data suggest that there may be at least two types of mechanism for renin release from hog kidney. One is of the nonselective type by which both active and inactive renin are released, as in the case of beta-adrenergic or prostaglandin stimulation. The other is a selective mechanism by which only active renin is preferentially released, as in the case of urinary or renal kallikrein stimulation.

1-Methyl-3-isobutylxanthine↗
PubMed1984

Demonstration of renin activity in purified rat Leydig cells: evidence for the existence of an endogenous inactive (latent) form of enzyme.

Previous histochemical studies demonstrated the specific localization of immunoreactive renin-like substance in Leydig cells of rat testes. The studies reported herein demonstrate a specific renin enzyme activity in the two purified populations of Leydig cells (I and II) of mature rat testes. Leydig cells of both populations also exhibited an inactive (latent) renin which was activated by the sulfhydryl reagents dithiothreitol, beta-mercaptoethanol, glutathione, and cysteine but not by limited proteolysis by trypsin, which is a characteristic activating agent for prorenin or inactive renin of the zymogen type. The activation of latent renin by dithiothreitol produced approximately 5-and 10-fold increases in renin activity in Leydig cell populations I and II, respectively. Active and latent renin showed strong affinity to an antirat renin immunoglobulin-Sepharose column, indicating a close immunological relationship of latent renin to active renin. Both active and latent renin from Leydig cell populations (I and II) exhibited the pH optimum of 6.0. The gel filtration of Leydig cell extracts characteristically revealed that the apparent mol wts of active and latent renin were 39,000 and 48,000, respectively. Both active and latent renin in Leydig cells remained almost at similar levels through four continuous subcultures. The activity of latent renin slightly increased during the four consecutive subcultures, while active renin levels remained almost constant.

Animals↗
PubMed1984

Gonadotropin-dependent renin in the rat testes.

Using specific anti-rat renal renin antibody, the presence of renin in the rat testis was demonstrated by biochemical determination of renin activity. There was no correlation between testicular and plasma renin activity, indicating independent control of testicular and plasma renin levels. Since specific immunohistochemical staining for renin had been observed exclusively in Leydig cells, the effects of hypophysectomy and gonadotropin treatment on the testicular renin were investigated. After hypophysectomy, renin level in the testis decreased significantly, whereas plasma renin was slightly increased. In contrast, testicular renin had remarkably increased through gonadotropin treatment. The results indicate the presence of gonadotropin-dependent renin in the Leydig cells, and suggest a role for it in regulating testicular functions.

Animals↗
PubMed1984

Atrial natriuretic factor: purification of active peptides, cloning of cDNA and determination of structures of active peptides and precursors.

Four peptides possessing both natriuretic and smooth muscle relaxant activities were purified from rat heart atrium and their amino acid sequences were determined. All contained a common sequence which contains a macro-ring structure formed by 17 amino acid residues and a disulphide bridge. The major atrial peptide in the atrium was identified as that containing 31 amino acid residues. The cDNA of the atrial peptide precursor was cloned and its nucleotide sequence determined. The amino acid sequence of the precursor deduced from the nucleotide sequence contained 152 residues and a potential signal peptide sequence characteristic of secretory polypeptides.

Amino Acid Sequence↗
PubMed1984

Ultrastructural immunocytochemical localization of renin and angiotensin II in the juxtaglomerular cells of the ischemic kidney in experimental renal hypertension.

Partial ligation of the rat aorta between the renal arteries induces acute hypertension with atrophy of the left (ischemic) kidney, intense stimulation of juxtaglomerular cell (JGC) secretory activity, and significant increases in renal cortical renin activity, in plasma renin activity, and in the plasma levels of angiotensin I (AI) and angiotensin II (AII). With the unlabeled antibody technique at the light-microscopic level and various dilutions of renin antiserum, immunoreactive renin can be visualized in the JGC of sham-operated controls with high dilutions of antiserum that do not reveal renin in the JGC of ischemic kidney. The reverse is true with AII antisera; ie, high dilutions of AII antisera immunostain the JGCs of ischemic kidney but not those of control kidney. With the protein A-gold technique at the electron-microscopic level, using gold particles of small and large size and immunoreacting the two faces of a fine section, renin and AII can be localized in the same JGC secretory granules. With the same technique (immunoreacting only one face of a fine section with small gold particles), quantitative analysis reveals a lower concentration of renin and a higher concentration of AII in the secretory granules of the ischemic kidney JGCs; these granules are also of smaller size than those of control kidney JGCs. AI cannot be visualized in these cells at either the light- or electron-microscopic level. These results indicate that AII co-localized with renin in JGC secretory granules and probably co-secreted, is not synthetized by these cells but is internalized following receptor binding.

Angiotensin II↗
PubMed1983

Rat kidney renin and cathepsin D: purification and comparison of properties.

Renin and cathepsin D were purified by seven-step procedures involving five steps common to both enzymes. These common five steps were extraction of freeze-dried kidney powder in 30% methoxyethanol-water, diethylaminoethyl-cellulose (DEAE-cellulose) batch absorption and elution, pepstatin-aminohexyl-Sepharose chromatography, Sephadex G-100 chromatography, and DEAE-cellulose chromatography. The renin component was purified further by passage through an anti-rat spleen cathepsin D immunoglobulin G-Sepharose (IgG-Sepharose) column followed by carboxymethyl-Sephadex (CM-Sepharose) chromatography which separated two renin components. Cathepsin D activity obtained by the fifth step was purified by passage through an anti-rat kidney renin IgG-Sepharose column followed by DEAE-Sephacel chromatography which separated three cathepsin D components. The homogeneity of renin and cathepsin D preparations was demonstrated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The two components of renins showed molecular weights of 42 000 and 36 000 by gel filtration and 38 000 and 36 000 by SDS gel electrophoresis, respectively. They showed isoelectric points of 5.35 and 5.65 by electrofocusing in 5% polyacrylamide gels. Their optimum pHs of enzyme activity were 6.5 as determined by using nephrectomized rat plasma as a substrate. Their specific angiotensin I (Ang I) generation activities were 158 and 146 micrograms of Ang I (microgram of protein)-1 h-1, respectively, which correspond to 1100 and 1020 Goldblatt units (mg of protein)-1 h-1. The three cathepsins showed molecular weights of 41 000, 43 000, and 41 000 by gel filtration and 46 000, 45 000, and 46 000 by SDS gel electrophoresis.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin I↗
PubMed1983

Rat atrial natriuretic factor. Purification and vasorelaxant activity.

The atrial natriuretic activity of rat heart has been found to exist in multiple forms. One of these factors has been purified to apparent homogeneity by a combination of gel filtration and high pressure liquid chromatography in two different systems and its amino acid composition determined. The purified active peptide is shown to have a molecular weight of approximately 3800. In addition, the vasorelaxant activity of rat atrium has been purified and found to co-chromatograph with the natriuretic activity in all chromatographic systems employed. Thus, the vasorelaxant activity resides in the natriuretic factor. The existence of this new multifunctional peptide implies a higher level of complexity for cardiovascular control of blood volume and pressure.

Amino Acids↗
PubMed1983

Mouse submaxillary renin has a protease activity and converts human plasma inactive prorenin to an active form.

The activation of inactive prorenin by active renin was investigated. Inactive prorenin extensively purified from human plasma was activated by active renin which had been purified from mouse submaxillary glands by multiple chromatographic steps. The apparent lack of protease activity in renin was puzzling in view of the close similarity of its active site structure with that of acid proteases. After a series of affinity chromatographic steps designed to eliminate minute contaminants, renin was found to contain a very low but finite level of a neutral protease activity which was equivalent to 1/40,000 of that of cathepsin D tested by hemoglobinolytic activity. The protease activity was considered as intrinsic to renin since it co-purified with renin persistently at a constant ratio to the renin activity, was precipitated by a monoclonal antibody specific for renin, showed a neutral pH optimum of the enzyme activity in the same pH range as that of renin, and was inhibited by pepstatin. The neutral protease activity is likely to mediate the activation of inactive prorenin.

Animals↗
PubMed1983

A 45 000 molecular weight human renin precursor is synthesized in a cell-free translation system.

Human kidney mRNA species were isolated and fractionated through a continuous sucrose gradient ultracentrifugation. mRNA fractions were translated by using a rabbit reticulocyte lysate and [35S]methionine as tracer. Double immunoprecipitation was carried out with highly specific anti-human renin and anti-rabbit gamma-globulin antisera. A 15S mRNA has been found to direct synthesis of a 45 000 molecular weight protein immunoprecipitable with anti-human renin. This protein is considered to be the ultimate precursor of renin (pre-prorenin).

Enzyme Precursors↗
PubMed1983

Pituitary-dependent renin-like immunoreactivity in the rat testis.

By means of a specific anti-rat renin antiserum, immunohistochemical staining was observed restricted to Leydig cells of rat testis. Specificity of the staining was ascertained by the absence of reaction with nonimmune serum or with the antiserum preincubated with rat renin. Specific staining of Leydig cells was absent in newborn rats; it developed with the onset of puberty. Staining was suppressed or abolished by hypophysectomy and estrogen treatment and was reduced by gonadotropin stimulation. Vasectomy destroyed the seminiferous epithelium but did not impair renin-like immunoreactivity of the interstitial tissue. It is concluded that Leydig cells contain a pituitary-dependent renin-like substance.

Age Factors↗
PubMed1983

Calmodulin antagonists stimulate renin release from isolated rat glomeruli.

Effects of calmodulin antagonists on renin release from isolated rat glomeruli were examined. The calmodulin antagonists used were N-(6-aminohexyl)-5-chloro-naphthalene-1-sulfonamide (W-7), triflupromazine and trifluoperazine. These drugs induced renin release from isolated glomeruli in a dose-dependent manner. The threshold concentration for renin release in the calcium-containing medium was 50 microM for W-7, 5 microM for triflupromazine and 2 microM for trifluoperazine respectively. The threshold concentrations were 2-5 times less in the calcium-free medium. The maximum levels of renin release by the three antagonists were similar in both calcium-containing and calcium-free media. In the absence of these antagonists, the basal rate of renin release in the calcium-free medium was markedly higher than in the calcium-containing medium. These results suggest that the calcium-calmodulin system inhibits renin release and that renin release is regulated by a mechanism different from the calcium-stimulated exocytotic mechanism by which many hormones are released.

1-Methyl-3-isobutylxanthine↗
PubMed1983

The subcellular distribution of renin in hog anterior pituitary.

Renin in hog anterior pituitary was found to be located principally in the particulate fractions. Density gradient centrifugation of the granular fraction revealed a discrete band of renin activity distinct from lysosomal and mitochondrial markers. This band has a density similar to that of known kidney renin secretory granules and may be due to renin secretory or storage granules in the anterior pituitary.

Animals↗
PubMed1983

Renin exists in human adrenal tissue.

Readily detectable levels of renin activity were demonstrated in human adrenal tissues. This activity was inhibited by specific antibody raised against pure renin, indicating that it was not due to the nonspecific action of proteases. The renin activity was predominantly in the cortex rather than in the medulla of the adrenal. An adrenal gland that was surgically removed from a patient with Cushing's disease and had high renin activity was used for further characterization of the enzyme. It shared many biochemical features with kidney renin, such as molecular weight, isoelectric point, glycoprotein nature, optimum pH of enzyme activity, affinity to pepstatin, and the presence of trypsin-activatable inactive renin. The lack of correlation between PRA and the adrenal renin, and the particulate localization of the subcellular distribution of adrenal renin suggested its local origin rather than contamination or contribution of the plasma enzyme.

Adrenal Glands↗
PubMed1983

Structure of mouse submaxillary gland renin.

To determine the structural basis for the highly specific action of renin, structural features of the active site and the complete amino acid sequence of mouse submaxillary gland renin were determined. A rapid method was developed for a large scale purification of renin from mouse submaxillary gland. The active site of renin was shown to consist of 2 aspartyl residues, 2 tyrosyl residues and one arginyl residue, the structures analogous to the active site of pepsin and other acid proteases. Renin was found to consist of one heavy chain (Mr = 31,036) and one light chain (Mr = 5,458) connected by a disulfide bridge. Amino acid sequences of these chains were determined using overlapping peptides generated by cleavage with cyanogen bromide, trypsin, Staphylococcus aureus protease and Lysobacter enzymogenes endoproteinase Lys-C. Sequences involving 2 catalytically essential aspartyl residues 32 and 215, characteristic to acid proteases, were found identical with pepsin, penicillopepsin and chymosin. The sequence of L-chain was homologous with carboxyl terminal region of porcine pepsin in 46% of amino acid residues. H-chain showed 41% homology with 284 residues on the amino-terminal side of the porcine pepsin molecule. Residues identical in renin and acid proteases are distributed throughout the length of the molecules, suggesting a similarity in their overall structure.

Amino Acid Sequence↗
PubMed1983

Local generation of angiotensin in the kidney and in tissue culture.

The renin-angiotensin system is an exception among the various peptide hormone producing mechanisms in that it is an extracellular system. It was not clear whether renin in tissues other than kidney participates in the extracellular system or an intracellular mechanism. We examined the possibility of intracellular formation of angiotensin II in these tissues by using cloned, renin containing cells in culture as models. Neuroblastoma cells, pheochromocytoma cells, adrenal cortical cells and juxtaglomerular cells were shown to contain renin, angiotensin I and angiotensin II. Presence of angiotensin I converting enzyme was also demonstrated in some cell lines examined. Even juxtaglomerular cells in the intact kidney were shown to contain angiotensin I and angiotensin II by immunohistochemical technique. These findings indicate an intracellular mechanism of angiotensin II formation in various tissues and suggest that angiotensin II may have local paracrine functions.

Adrenal Cortex↗