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T Inagami

Publications and source records attributed to T Inagami.

At least 361 records · Page 20Linked to original sources
PubMed1985

A role for the adrenal renin-angiotensin system in the regulation of potassium-stimulated aldosterone production.

Potassium is a major regulator of aldosterone production. It also increases adrenal renin. The causal relationship between potassium and adrenal renin is not known. To evaluate the role of the intraadrenal renin-angiotensin (ANG) system in potassium-stimulated aldosterone synthesis and release, specific adrenal renin activity, PRA, and plasma aldosterone were measured during potassium loading or captopril treatment in the rat. Adrenal ANGs were determined using a HPLC system combined with RIA to obtain quantitative information on the components of the adrenal renin-ANG system. In addition, the effect of pretreatment with captopril on aldosterone production by isolated adrenal glomerulosa cells was examined. In intact animals potassium loading markedly increased adrenal renin and plasma aldosterone, whereas PRA was suppressed. The administration of captopril to rats in normal potassium balance did not suppress plasma aldosterone. Captopril treatment during potassium loading inhibited the potassium-induced increase in aldosterone. Furthermore, pretreatment with captopril suppressed adrenal ANG II and reduced the response of aldosterone production to extracellular potassium concentration by isolated adrenal glomerulosa cells in vitro. These results suggest that the adrenal renin-ANG system plays a significant role in the control of aldosterone production under potassium stimulation.

Adrenal Glands↗
PubMed1985

Induction of renin activity by gonadotropic hormones in cultured Leydig tumor cells.

The hormonal regulation of renin activity in cloned and cultured Leydig tumor cells (designated MA-10) was examined. The treatment of Leydig cell cultures with bovine LH (bLH), hCG, or with (Bu)2cAMP elicited a dose- and time-dependent induction of renin activity and a concomitant increase in steroid biosynthesis. The optimum concentration of hCG was 25 ng/ml, which caused an average 25-fold increase in renin activity compared to the control value. bLH action was optimum at 75-100 ng/ml and induced an approximately 35-fold increase in renin activity. The maximum inducible level of renin activity was attained after 8-9 h of hormone treatments. The addition of progesterone (the major steroid product of the MA-10 cells) did not induce a significant increase in renin activity. Treatment of MA-10 cells with epidermal growth factor also failed to produce any increase in renin activity. The optimum concentration of (Bu)2cAMP was 800 microM for the induction of renin activity and caused an approximately 40-fold increase compared to the control value. Renin activity induced by bLH, hCG, or (Bu)2cAMP was completely inhibited by mouse anti-renin antibody, indicating the specific nature of renin. Upon withdrawal of (Bu)2cAMP from the culture medium, renin activity gradually declined to the control level, and with retreatment of these cultures with (Bu)2cAMP, a newly induced state of enzyme activity was resumed. Indirectly, the role of new protein and RNA synthesis was examined during hormonal regulation of renin induction using protein and RNA synthesis inhibitors such as cycloheximide, puromycin, actinomycin D, or rifampicin. Both protein and RNA synthesis inhibitors blocked the induction of renin activity in the presence of all three inducing agents, bLH, hCG, or (Bu)2cAMP. The results provide evidence that the induction of renin activity is modulated by bLH, hCG, or (Bu)2cAMP and represent the de novo synthesis of enzyme molecules.

Angiotensin I↗
PubMed1985

Immunohistological evidence for renin in human endocrine tissues.

The peroxidase-labeled antibody method and the avidin-biotin-complex method with antiserum to purified human kidney renin were used to identify renin in human endocrine tissues. Renin immunoreactivity was found in some large cells of the anterior pituitary, the zona glomerulosa and the zona reticularis of the adrenal, the Leydig cells of the testis, and the follicular epithelial cells of the thyroid and prostate glands. The specificity of the immunohistochemical reaction was confirmed by immunoabsorption tests. The specific localization of immunoreactive renin in each tissue suggests a possible role of renin in the function of these tissues.

Adrenal Glands↗
PubMed1985

Evidence for the existence of des-Asp1-angiotensin II in human uterine and adrenal tissues.

Renin is present in various tissues outside the kidney. In contrast, the levels of angiotensins (ANG), the active products of the renin-angiotensin system, have not been thoroughly evaluated in tissues. In this study, we demonstrated the presence of immunoreactive (ir) ANG I and ANG II in various human tissues by RIA. Of the tissues examined, uterine tissue contained the most ir-ANG II. Since the anti-ANG II antibody used had significant cross-reactivity with ANG III, high performance liquid chromatography was performed to separate ANG II from ANG III. The major portion of the ir-ANG II in the plasma was ANG II. In contrast, the major portion of the ir-ANG II in uterine tissue was determined to be ANG III, a known biologically active peptide. The adrenal gland and testis also contained ANG III. From these results, it can be postulated that ANG III may contribute to the biological activity of ANG in some tissues.

Adrenal Glands↗
PubMed1985

Renin and angiotensins in cultured mouse adrenocortical tumour cells.

Mouse adrenal tissue has been reported to contain high renin activity. However, it is not clear whether the renin is produced inside the tissue or is derived from a blood-borne component. We have investigated a cloned cell line of mouse adrenocortical tumour (Y-1) which has a steroidogenic activity. Sizable quantities of renin were demonstrated, predominantly in the cell lysate. This renin activity was distinguished from cathepsin D in view of its specific affinity to anti-renin antibody, optimal pH was determined, and the substrate specificity was checked with haemoglobin. Immunoreactive angiotensins were also detectable, but were demonstrated both in the cell and in the culture medium. This study provides further evidence for the existence of renin intrinsic to the adrenal gland. This study also suggests an intracellular role for renin and possible secretion of generated angiotensins.

Adrenal Cortex Neoplasms↗
PubMed1985

Biochemical studies of rat atrial natriuretic factor.

The natriuretic substances were purified from rat atrium (ANF, atrial natriuretic factor) and were shown to be identical with the inhibitor of norepinephrine-induced contraction of smooth muscle. Their four native forms were isolated. Amino acid sequence analyses showed they are peptides with 35, 31, 30 and 25 amino acid residues respectively and contain a ring structure consisting of 17 amino acid residues and a disulfide bridge. The presence of a high molecular weight prohormone was shown. cDNA coding for the precursor was cloned and used to deduce the amino acid sequence of the preprohormone. Genomic DNA for ANF was cloned and the presence of two introns were found. Several ANF peptides were synthesized. Structure-function studies showed that the ring structure is essential for the activity. Antibodies produced against the synthetic 25 amino acid residue ANF were used to develop radioimmunoassay. The presence of ANF in rat plasma was demonstrated as evidence that ANF is a circulating hormone. ANF was also found in the hypothalamus of rats. The quantitative determination of the synthetic ability of ANF has been determined by the application of ANF cDNA for the quantification of ANF messenger RNA. Immunohistochemical methods localized ANF in cardiac atriocytes, gonadotrophs in anterior pituitary and adrenal medulla (chromaffin cells). A strong immuno-reactivity was found in dark cells of the collecting ducts of the kidney. ANF increases cyclic GMP in target cells suggesting that cyclic GMP may be the intracellular mediator of ANF action.

Adrenal Cortex↗
PubMed1985

Comparison of serum phospholipid fatty acids among fishing and farming Japanese populations and American inlanders.

Fatty acid compositions of phospholipids in serum were analyzed in three different populations in seaside fishing and mountain farming villages in Japan and in inland inhabitants of the United States of America. The percentage of omega-3 polyunsaturated fatty acids, i.e., eicosapentaenoic acid (20:5) and docosahexaenoic acid (22:6) was significantly low in United States inlanders with a high coronary heart disease morbidity compared with both populations in Japan with low morbidity. The level of arachidonic acid (20:4) was the same among these three inhabitant population groups. However, omega-3 polyunsaturated fatty acid levels were significantly higher in the inhabitants of fishing villages with relatively low stroke morbidity than in those of farming villages with extremely high stroke morbidity in Japan.

Agriculture↗
PubMed1985

Preparation of a specific high-titer antibody against rat kidney renin.

Specific high-titer antibodies to rat kidney renin were raised using pure rat kidney renin conjugated with tetanus toxoid as antigen. The titers of two antisera for 50% inhibition of rat kidney renin activity were 80 000 and 700 000, respectively. The antibody inhibited the enzyme activities of hog kidney renin and mouse submaxillary gland renin at concentrations 1 000 times higher than required for rat kidney renin but did not inhibit human renal renin or rat kidney cathepsin D. The antibody can be used for characterizing the physiological and pathophysiological role of renin in blood pressure regulation, for the histochemical localization of renin in rat tissues and for distinguishing specific renin activity from the nonspecific renin-like activity of cathepsin D.

Animals↗
PubMed1984

Detection of renin mRNA in mouse testis by hybridization with renin cDNA probe.

Using 32P-labeled DNA complementary to mouse submaxillary gland renin mRNA, we probed mRNA gel blots from mouse testis and kidney tissues. Poly(A)-RNA from testis contained a hybridizable RNA species which was blotted onto nitrocellulose paper. The molecular size of testicular renin mRNA (approximately 1600 nucleotides in length) was not significantly different from tht of kidney renin mRNA. Densitometric scan revealed that the content of renin mRNA in mouse testis was approximately 5-fold lower than that in mouse kidney. These results support the proposal that mouse testicular cells synthesize renin.

Animals↗
PubMed1984

Cloning of genomic DNA for human atrial natriuretic factor.

A human genomic DNA clone for atrial natriuretic factor (ANF) gene was isolated from a human gene library using the previously cloned cDNA for rat ANF as a probe. Partial nucleotide sequencing of the cloned DNA revealed the location of a 120-bp long intron between Lys-41 and Asn-42 of the ANF precursor. Restriction mapping also suggested the existence of at least one other intron in or proximal to the 3' -untranslated region.

Amino Acid Sequence↗
PubMed1984

Atrial natriuretic factor in rat hypothalamus, atria and plasma: determination by specific radioimmunoassay.

A rapid and reproducible radioimmunoassay method was developed for rat atrial natriuretic factor (ANF)-IV. The method is also applicable to human atrial peptide. ANF was detected in rat hypothalamus (5.03 pmoles/g tissue), right (86.8 pmoles/mg tissue) and left atria (52.5 pmoles/mg tissue), and plasma (156 fmoles/ml). After high salt intake immunoreactive ANF in atria and plasma increased significantly, while a significant decrease was observed in hypothalamus. Gel chromatography revealed high and low molecular weight ANF in atria and hypothalamus while only a low molecular weight form was found in plasma.

Amino Acid Sequence↗
PubMed1984

Rat atrial natriuretic factor: isolation, structure and biological activities of four major peptides.

Four peptides possessing both natriuretic activity and smooth muscle relaxant activity were isolated from rat atrium and their amino acid sequences determined. The four peptides designated ANF-I, ANF-II, ANF-III and ANF-IV containing 35, 31, 30 and 25 amino acid residues, respectively, were obtained in a molar ratio of 4:60:20:16. The predominant species ANF-II, which may represent the native form of ANF, has the following sequence: (H2N)-G-P-R-S-L-R-R-S-S-C-F-G-G-R-I-D-R-I-G-A-Q-S-G-L-G-C-N-S-F-R-Y-(COO H) in which Cys-10 and Cys-26 are disulfide linked. Cleavage of the aspartyl linkage at position 16 by staphylococcal protease caused complete inactivation, indicating that the ring conformation is essential. The dose-response relationships determined for the four peptides in relaxing norepinephrine-induced contraction of rabbit thoracic aorta showed half-maximum relaxation at concentrations ranging from 1.5 X 10(-9) to 2.5 X 10(-9) M. Comparable dose-response relationships were observed in relaxation of carbacol-induced contraction of chick rectum strips as tested with ANF-II and ANF-IV.

Amino Acid Sequence↗
PubMed1984

Synthesis of atrial natriuretic peptides and studies on structural factors in tissue specificity.

Two atrial natriuretic peptides, containing 25 amino acid residues, ANF IV, and 21 amino acid residues, ANF V, were synthesized by a solid phase method and oxidized with K3Fe(CN)6 to form a disulfide bridge. Synthetic ANF IV exhibited a natriuretic activity with an ED50 70 times higher than that of synthetic ANF V, whereas the longer peptide was only 2.5 times more potent in chick rectal smooth muscle relaxant activity. Both peptides inhibited norepinephrine-induced contraction of rabbit aorta. The shorter peptide, ANF V, was 300 times less efficient than the longer peptide, ANF IV. It is proposed that the carboxy-terminal of ANF IV seems to have a modulating effect on receptor affinity in kidney and vascular tissue.

Animals↗
PubMed1984

Evidence for intracellular formation of angiotensins: coexistence of renin and angiotensin-converting enzyme in Leydig cells of rat testis.

Leydig cells were purified from rat testes by discontinuous metrizamide density gradient and were shown to contain renin (EC 3.4.99.1), angiotensin-converting enzyme (dipeptidyl carboxypeptidase, (EC 3.4.15.1), and the peptide hormone angiotensins I, II and III as determined by the combined HPLC and radioimmunoassay. In germinal cells only angiotensin II (AII) was found at a significant level. These findings provide evidence for intracellular formation of AII in testicular cells and demonstrate that an intracellular renin-angiotensin system exists in normal non-transformed cells.

Angiotensins↗
PubMed1984

Generation of angiotensins in cultured pheochromocytoma cells.

Cultured rat pheochromocytoma cells, PC-12, were found to contain renin-like activity. The activity which was inhibited by monospecific antibodies to rat renal renin showed a pH optimum between 6 and 7, indicating that it was a specific renin. The cells also contained angiotensin I and angiotensin I converting enzyme. Angiotensin II/III were also detected in lysate. These findings indicated an intrinsic pathway of angiotensin formation in pheochromocytoma. The formation of angiotensins in pheochromocytoma cells suggests modulating functions of angiotensin on neurotransmitter release from adrenal medulla.

Adrenal Medulla↗
PubMed1984

Rat atrial natriuretic factor: complete amino acid sequence and disulfide linkage essential for biological activity.

The complete amino acid sequence of an atrial natriuretic peptide from rat possessing both natriuretic and smooth muscle relaxant activity has been determined. The peptide has the structure (sequence in text) and a calculated molecular weight of 2,706. The ring structure formed by the disulfide linkage between the two half-cystine residues was found essential for both the natriuretic activity and smooth muscle relaxant activity. The purified peptide caused 50% relaxation of norepinephrine (5 X 10(-8)M) induced contraction of rabbit thoracic aorta at the concentration of 2 X 10(-9)M and complete relaxation at 6 X 10(-9)M.

Amino Acid Sequence↗
PubMed1984

Coexistence of renin and angiotensin II in epitheloid cell secretory granules of rat kidney.

The distribution of renin and angiotensin II (ANG II) in juxtaglomerular epitheloid cells of control and adrenalectomized rats was studied, using specific antisera and the protein A-gold technique in Lowicryl- and glycol methacrylate-embedded tissue. The matrix of virtually all mature secretory granules of epitheloid cells contains not only renin, but also ANG II. On adrenalectomy, the concentration of both renin and On adrenalectomy, the concentration of both renin and ANG II in the granule internum increases markedly, as indicated by the density of the immunolabel. Given the coexistence of renin and ANG II in the granule matrix, it is quite probable that, with each secretory event, a certain amount of ANG II is released together with renin. Further experiments will have to show if this amount of ANG II cosecreted with renin is sufficient to elicit immediate local intrarenal actions. ANG I, as well as angiotensinogen and converting enzyme, were not found in epitheloid cells. It is therefore inferred that ANG II is not generated intracellularly, but within the extracellular space and subsequently taken up by pinocytosis and incorporated into the secretory granules of epitheloid cells.

Adrenalectomy↗