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Biomedical subjects

K Naruse

Publications and source records attributed to K Naruse.

At least 253 records · Page 14Linked to original sources

A case of adrenal tumor producing renin, aldosterone, and sex steroid hormones.

A 27-year-old woman with an adrenal tumor that produced renin and aldosterone, associated with hypertension and adrenogenital syndrome, is described. Severe hypertension, cardiomegaly, a low serum potassium level, clinical symptoms of adrenogenital syndrome, and a left upper abdominal tumor also were found. Endocrinological studies showed that plasma and urinary levels of sex steroid hormones such as dehydroepiandrosterone, androsterone, and testosterone were markedly increased. Plasma renin activity, plasma angiotensin II, and plasma aldosterone levels also were increased markedly, although deoxycorticosterone levels remained within the normal range. The possibility of renovascular hypertension was excluded by angiography of the renal artery and by venous sampling of plasma renin activity. Abnormal elevations in plasma aldosterone levels persisted despite normalization of plasma angiotensin II by converting enzyme inhibitor administration. It was suspected that this patient had an adrenal tumor producing renin as well as sex steroids and aldosterone. Microscopy of the resected tumor revealed that the tumor was composed mostly of cells with large nuclei and light cytoplasm. The tumor contained dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, aldosterone, and renin. Immunohistochemical study showed that some of the tumor cells produced renin. Biopsy of the left renal tissue showed evident atrophy of the juxtaglomerular cells and pronounced arteriosclerosis. After resection of the tumor, all blood and urinary levels of the abnormally increased hormones returned to a normal range and an apparent fall of blood pressure was noted. To our knowledge, this is the first report of a renin and aldosterone-producing adrenal tumor associated with hypertension and adrenogenital syndrome.

Adrenal Gland Neoplasms↗

Renin in the rat pituitary coexists with angiotensin II and depends on testosterone.

In the rat pituitary gland, immunoreactive angiotensin II (ANG II), renin, and LH, but not PRL, were found within the same cells of the anterior pituitary gland by staining with the avidin-biotin complex method in adjacent sections. No renin-positive staining was observed in the pituitary of the rats after 10 days of castration, but positive staining reappeared after 8 weeks. This effect of castration on renin immunoreactivity was abolished by the simultaneous administration of testosterone. In contrast, ANG II immunoreactivity was unaffected by castration. The intensity of renin immunoreactivity in the pituitary was less prominent in the female than in the male rat. These results suggest that there exists a pituitary renin-angiotensin system localized in the gonadotrophs and that the pituitary renin is under androgenic control.

Angiotensin II↗

Intracellular action of renin, angiotensin production and release.

The enzyme renin has been purified and characterized by structural analysis. Pure renin protein was used to produce a specific antibody to renin, which was useful in demonstrating the presence of a specific renin in many tissues other than kidney. In these cells angiotensins I and II and angiotensin converting enzyme were found to coexist with renin by immunohistochemical studies and by the direct determination with cultured cells. Studies with these cells indicated the local production of renin, angiotensinogen and angiotensins in these cells. Angiotensin II produced in the cultured cells was secreted to the outside of the cells while more than 95% renin remained within the cells. Secretion of angiotensin II from the angiotensin producing cells was demonstrated with perfused mesenteric artery. The secretion was stimulated by the adrenergic beta-agonist isoproterenol in a dose-dependent manner and specifically inhibited by a beta 2-antagonist. Angiotensin II secreted from the vascular bed by the beta 2-adrenoceptor stimulation acts locally to facilitate norepinephrine release. These studies demonstrate local production and secretion of angiotensin II and define its physiological role.

Angiotensin II↗

Localization of components of the renin-angiotensin system within the kidney.

Evidence accumulates that intrarenal angiotensin II (AngII) plays important roles in the regulation of renal functions. To determine the mechanism and site of the intrarenal formation of AngII, we employed histochemical and cell biological methods. Immunohistochemical studies have revealed the coexistence of renin and AngII in juxtaglomerular (JG) cells, and electron microscopic studies and subcellular organelle fractionation have demonstrated the colocalization of renin and angiotensin in renin granules. The mechanism of this AngII accumulation has been investigated. Immunoreactive angiotensin I (AngI) appeared slowly in JG cells after prolonged administration of angiotensin-converting enzyme (ACE) inhibitors. Cloned and cultured renin-containing cells derived from rat kidney were also found to contain renin, ACE, and AngI and AngII. The subcellular fractionation of renin granules from rat kidney homogenate demonstrated AngI and AngII in the renin granule fractions. These findings suggest the formation of both angiotensins in JG cells. To study the release of AngII, we determined the presence of the angiotensins in renal lymph. Renin was found in renal lymph at a high concentration. Both AngI and AngII were also present in renal lymph in moderate concentrations. It is possible that AngII in the interstitial fluid may play a role in the regulation of renal functions. From these results it has been concluded that AngII is formed in JG cells in the kidney and is secreted with renin into interstitial fluid and plasma, and that AngII formed in the kidney cells may participate in various renal functions.

Angiotensin II↗

Antisera to atrial natriuretic factor reduces urinary sodium excretion and increases plasma renin activity in rats.

Although the presence of atrial natriuretic factor in the blood has been demonstrated by radioimmunoassay, its biological activity and physiological significance has not been elucidated. Using specific antiserum against atrial natriuretic factor, we investigated the effect of passive immunization in rats. A significant reduction of urine output and urinary sodium excretion lasted for about 30 min after intravenous administration of antiserum. The effects were more pronounced in rats pretreated with deoxycorticosterone acetate and saline. Plasma renin activity was increased after the administration of antiserum. No significant effects on the urinary sodium excretion was observed following injection of normal rabbit serum. The results of this study provide evidence indicating that endogenous atrial natriuretic factor plays an important role in the regulation of urinary water and sodium excretion and plasma renin activity.

Aldosterone↗

Atrial natriuretic factor inhibits vasopressin secretion from rat posterior pituitary.

The effects of synthetic atrial natriuretic factor (ANF) were studied in superfused rat posterior pituitary gland. ANF (10(-6)M, 10(-10)M) significantly inhibited basal as well as KC1 (50 mM) or angiotensin II-stimulated immunoreactive arginine vasopressin secretion. The magnitude of inhibition was greater at 10(-6)M than at 10(-10)M. ANF also decreased cAMP secretion and increased cGMP secretion from the posterior pituitary. These results suggest that ANF directly acts on the posterior pituitary to inhibit arginine vasopressin secretion and that this effect is, at least, partly mediated by the changes in cyclic nucleotide production.

Angiotensin II↗

Regional distribution of renin and angiotensinogen in the brain of normotensive (WKY) and spontaneously hypertensive (SHR) rats.

The distributions of angiotensinogen and specific renin activity were examined in the brains of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto controls (WKY). Specific renin activity was markedly elevated in the pituitary of SHR compared to WKY. Renin levels in other regions of SHR brain were either significantly lower or similar compared to WKY. In contrast, angiotensinogen was significantly elevated in several regions of SHR compared to WKY brain. These results indicate involvement of a brain renin-angiotensin system in the development of genetic hypertension.

Angiotensinogen↗

The renin-angiotensin system in the rat anterior pituitary: colocalization of renin and angiotensin II in gonadotrophs.

Discovery of components of the renin-angiotensin system (RAS) in the adenohypophysis of several species has prompted speculation concerning the location and possible function of a pituitary RAS. Although both renin and angiotensin II have been localized within the rat adenohypophysis, their colocalization has not been previously demonstrated within the same cells. In the present study, immunohistochemical staining by the avidin-biotin-peroxidase complex technique was used to demonstrate the coexistence of renin and angiotensin II in adenohypophyseal cells identified morphologically and immunocytochemically as gonadotrophs. These results support the existence of an adenohypophyseal RAS, at least part of which is under intracellular control. The influence of this system on control of fluid balance, blood pressure, and the secretion of other hypophyseal hormones is discussed.

Angiotensin II↗

The production of cloned fish in the medaka (Oryzias latipes).

The measurement of cellular DNA content by DNA microfluorometry revealed that medaka embryos that were fertilized with normal sperm and exposed to heat shock (41 degrees C for 3 min) or hydrostatic pressure (700 kg/cm2 for 10 min) at 85-95 min after insemination were tetraploid. Embryos fertilized with normal sperm and exposed to heat shock (41 degrees C for 2 min at 2-3 min after insemination) were triploid. These results suggest that heat shock or hydrostatic pressure at 85-95 min after insemination arrests the first cleavage, while heat shock at 2-3 min after insemination arrests the second meiotic division. Medaka clones have been produced by the following method: Eggs from orange-red or variegated variety were activated by UV-irradiated, genetically impotent sperm of wild-type fish (UV sperm). The haploid eggs obtained were diploidized by preventing the first cleavage with heat shock or hydrostatic pressure to produce homozygous females. Each of the two homozygous females was mated with vasectomized male in isotonic balanced salt solution to collect unfertilized eggs. The collected eggs were activated with UV sperm and converted from haploid to diploid by arrest of the second meiotic division with heat shock. Hatched fry of each homozygous diploid (all females) were fed with a methyltestosterone-containing diet (40 micrograms/gm diet) to produce sex-reversed males, which were mated with brood females, and thus two cloned lines were obtained.

Animals↗

Synthetic rat atrial natriuretic factor inhibits in vitro and in vivo renin secretion in rats.

We investigated the action of a synthetic rat atrial natriuretic factor (ANF) with 28 amino acids on renin secretion in rats. Renin release by kidney cortex slices was determined after 90 min of incubation at 37C. ANF inhibited basal renin release in a dose-related fashion. ANF also decreased cAMP release and increased cGMP release in a dose-dependent manner. Renin release stimulated by 10(-7) M isoproterenol was inhibited by ANF with an ID50 of 5.8 x 10(-8) M. The renin-inhibitory effect was not calcium-dependent. In anesthetized rats, a bolus IV dose of ANF decreased plasma renin activity and cAMP concentration, but increased cGMP concentration. These data suggest that ANF inhibits renin secretion via the direct action on juxtaglomerular cells and that this effect may be partly mediated by the changes in cyclic nucleotide production.

Angiotensin I↗

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↗

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↗

In vivo evidence of cortisol secretion by aldosterone-producing adenomas.

This study was done to confirm that aldosterone-producing adenomas secrete cortisol in vivo. Plasma cortisol and aldosterone concentrations were measured in samples obtained by selective adrenal-vein sampling in 8 patients with primary aldosteronism due to unilateral adenoma. All cases revealed higher adrenal-vein plasma cortisol concentrations on the adenoma side than the opposite, irrespective of adenoma location. These concentrations correlated significantly with plasma aldosterone concentrations (r = 0.972, P less than 0.001) in effluents from the adenoma side, but not from the opposite. Plasma concentrations also correlated significantly with estimated adenoma volume (r = 0.918, P less than 0.05). These findings strongly suggest that aldosterone-producing adenomas secrete cortisol in vivo. In a second study, we used metyrapone to test 6 patients with adenomas. Their responsiveness to cortisol and corticotrophin was found to be the same as that in normal subjects, suggesting that adenoma-secreted cortisol did not disturb the relationship between corticotrophin and cortisol. We thus concluded that cortisol is secreted concomitantly with aldosterone from aldosterone-producing adenomas under corticotrophin influence.

Adenoma↗

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↗

Endocrine characterization of the adrenal adenomas in a case of primary aldosteronism.

A 48-year-old man with typical clinical and biochemical features of primary aldosteronism was revealed on operation to have two adrenocortical adenomas in the left gland. An ACTH-dependent pattern of aldosterone secretion was demonstrated in terms of the parallel circadian rhythm of aldosterone with cortisol and the exaggerated response to ACTH but not to angiotensin II. Aldosterone and cyclic AMP release in vitro was studied using collagenase-dispersed cells of each adenoma. Not only the large adenoma but the small one showed basal and ACTH-stimulated releases of aldosterone greater than those by the adjacent tissue. In response to angiotensin II and potassium, the small adenoma showed a larger maximum increment of aldosterone than the large adenoma. This difference in endocrine features of the two adenomas suggests a possible transformation in their nature during development. An exaggerated cyclic AMP release by the adenomas in response to ACTH in vitro suggested the possible role of increased adenylate-cyclase activity in the hyperresponse of aldosterone to ACTH in this case.

Adenoma↗

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↗

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↗

Brain renin.

Although the brain contains cathepsins at high concentrations which exhibit a non-specific renin-like activity at acidic pH, the presence of specific renin in the brain has been demonstrated by characterizing its specific properties. Renin was separated from cathepsin by affinity chromatography on casein-Sepharose. Brain renin showed neutral pH optima for the reaction to generate angiotensin I. The presence of inactive prorenin was also found. The isoelectric points of brain renin were significantly lower differences from that of renal or plasma renin. Immunohistochemical studies demonstrated a wide-spread localization of renin in many different regions. Angiotensin II, the final product of the prohormone-to-hormone conversion reaction mediated by renin and angiotensin converting enzyme, was found to exist in the same cell as renin by immunohistochemical studies of brain sections and with cloned and cultured neuroblastoma cells. This is the first demonstration of the mechanism of peptide hormone formation in neuronal cells. Similar intracellular formation was demonstrated in gonadotrophs of adenohypophysis. Coexistence of renin and angiotensin II was demonstrated in some cells. Electrophysiological studies have shown that angiotensin II functions to disinhibit the inhibition of neuronal response to electrical stimuli in the hippocampus.

Angiotensin II↗