Biomedical subjects

K Naruse

Publications and source records attributed to K Naruse.

At least 19 recordsLinked to original sources

PubMed1992

Histological study on ouabain immunoreactivities in the mammalian hypothalamus.

The endogenous digitalis-like factor (EDLF) which has recently been purified from human plasma and identified as 'ouabain', a cis-trans-cis steroid of plant origin, is thought to be similar to the hypothetical humoral factor, 'endogenous digitalis-like substance (EDLS)'. In order to examine the hypothesis that EDLS is produced in the hypothalamus, we prepared an ouabain-specific antibody, and applied it to rat and macaque brains. Ouabain immunoreactivities were observed in the hypothalamus of both species. The immunopositive neurons were distributed in paraventricular and supraoptic nuclei, and some other hypothalamic regions. Their nerve fibers were seen abundantly in the hypothalamo-neurohypophysial regions. These results strongly support the possibility of existence of cis-trans-cis steroid including EDLF in mammalian brain.

Animals↗

PubMed1992

A highly repetitive interspersed sequence isolated from genomic DNA of the Medaka, Oryzias latipes, is conserved in three other related species within the genus Oryzias.

A highly repeated interspersed sequence (OLR1) was isolated from a genomic DNA library of the Medaka, Oryzias latipes. The OLR1 was about 160 base pairs (bp) in length. As judged from the results of colony hybridization experiments, OLR1 is one of the major repeated DNA sequences in the Medaka genome and is present in every 136 kb on average. Results of Southern and colony-hybridization analyses indicate that OLR1 is a small interspersed repetitive element (SINE). OLR1-related sequences were conserved in other three species (O. luzonensis, O. curvinotus, and O. mekongnensis) within the genus Oryzias as a repetitive sequence. These results lend support at the DNA level to the hypothesis that these four species form one group in the genus Oryzias, as has been suggested from an analysis of their karyotypes (Magtoon and Uwa, '85, Proc. Jpn. Acad., Ser. B, 61:157-160).

Animals↗

PubMed1992

Differential responses of Ca-activated K channels to bradykinin in sensory neurons and F-11 cells.

The nonapeptide bradykinin (BK) excites a subset of dorsal root ganglion (DRG) neurons with putative nociceptive functions by stimulating an inward cation current. In addition, BK stimulates various intracellular signaling pathways including an elevation of intracellular Ca2+. In a DRG neuron x neuroblastoma hybrid cell (F-11), BK stimulates similar increases in intracellular [Ca2+] and inward current but also elicits a large transient outward current through Ca(2+)-activated K channels. We have investigated the mechanisms underlying differential expression of outward current responses in the two cell types at the single channel level. Although K(Ca) channel activity appears in inside-out patches from both cells exposed to Ca2+, BK applied to the extrapatch membrane of cell-attached patches activates K(Ca) channels in F-11 but not DRG neurons. Whereas single K(Ca) channels are quantitatively similar in terms of conductance, voltage-dependence, and sensitivity to tetraethylammonium, they differ in sensitivity to intracellular Ca2+. Channel activation in both cells requires at least four Ca2+ ions, but half-maximal activation occurs at slightly higher [Ca2+] for DRG neurons. The shift in the Ca2+ dose-response curve combined with the steep [Ca2+] dependence of channel open probability makes it less likely that a BK-induced rise in internal [Ca2+] induced will trigger a transient outward current and resultant hyperpolarization in a DRG neuron.

Animals↗

PubMed1992

Endothelin stimulates aldosterone secretion in vitro from normal adrenocortical tissue, but not adenoma tissue, in primary aldosteronism.

In addition to vasoconstriction, endothelin (ET) has been reported to show various endocrine actions in animals. However, no data have emerged concerning the effect of ET on adrenal function in humans. We, therefore, investigated the effects of ET on aldosterone and cortisol secretion from adrenocortical tissues obtained from normal subjects (n = 6) and patients with primary aldosteronism (n = 5). Adrenal tissue slices were incubated at 37 C for 120 min in modified Krebs-Ringer solution containing glucose and HEPES. ET increased aldosterone secretion from normal adrenocortical tissue in a dose-dependent manner, with an ED50 of 0.036 nmol/L, although the maximum response was small compared with that to angiotensin-II. ET also stimulated aldosterone secretion from tissues adjacent to the adenoma, but not from the adenoma, in patients with primary aldosteronism. The effects of ET on aldosterone secretion were significantly suppressed by calcium channel blockade with nicardipine. ET did not affect cortisol secretion from the adrenal tissues. These results suggest that ET is one of the factors that regulates aldosterone secretion in humans.

Adenoma↗

PubMed1992

Endothelin-3 immunoreactivity in gonadotrophs of the human anterior pituitary.

Endothelin (ET), originally discovered in vascular endothelial cells, has also been demonstrated in nonvascular tissues. The present study was undertaken to elucidate the presence of ET in the human pituitary. The avidin-biotin complex method with antiserum to ET-1 (and ET-2) or ET-3 was used to identify ET in human pituitaries obtained by autopsy. ET-3 immunoreactivity was found in the cytoplasm of large ovoid cells of the anterior pituitary. Using the double staining method, the cells containing ET-3 immunoreactivity were differentiated from cells containing ACTH, TSH beta, GH, PRL, and protein S-100. By staining with anti-LH beta antiserum in adjacent sections and using the double staining method, the cells were identified as gonadotrophs. No staining was observed in the posterior pituitary. In addition, no ET-1 (and ET-2) immunoreactivity was detected. The specific localization of ET-3 immunoreactivity in the gonadotrophs of the human pituitary suggests a possible role of ET-3 in the regulation of anterior pituitary function.

Adolescent↗

PubMed1992

A patient with a prolactinoma associated with an aldosterone producing adrenal adenoma: differences in dopaminergic regulation of PRL and aldosterone secretion.

A patient with a rare combination of prolactinoma and aldosterone producing adrenal adenoma (APA) was reported in relation to studies concerning dopaminergic regulation of PRL and aldosterone secretion. The patient is a 38-year-old female with plasma PRL and aldosterone concentrations (PAC) of 563 ng/ml and 54 ng/dl, respectively. A bolus of 10 mg of metoclopramide significantly increased plasma PRL in 6 normal subjects and in 4 patients with APA, whereas the responses were blunted in 7 patients with prolactinoma and in our patient. The response of aldosterone to metoclopramide was less than that of PRL, but similar in all studied subjects, indicating that the dopaminergic inhibition of aldosterone secretion is less than that of PRL in normal subjects and did not change in patients with APA or prolactinoma. Oral administration of 2.5 mg of bromocriptine suppressed plasma PRL significantly in all the subjects studied, but did not produce any consistent changes in PAC. Discrepancies in the response of PRL and aldosterone to metoclopramide and to bromocriptine suggest a difference in the dopaminergic regulation of PRL and aldosterone secretion in both normal subjects and patients with prolactinoma and APA. It is unlikely that reduced dopaminergic inhibition is the basis for hypersecretion of PRL and aldosterone in our patient.

Adenoma↗

PubMed1992

Increased plasma endothelin in NIDDM patients with retinopathy.

OBJECTIVE: To elucidate the significance of ET in diabetic microvascular disease. RESEARCH DESIGN AND METHODS: We determined plasma levels of ir-ET-1 in 25 NIDDM patients without hypertension and/or renal dysfunction. RESULTS: The plasma levels of ir-ET-1 in NIDDM patients with simple (n = 8) and proliferative (n = 8) retinopathy were 0.58 +/- 0.04 pM and 0.60 +/- 0.04 pM, respectively, which were significantly higher than those in normal, nondiabetic subjects (0.24 +/- 0.02 pM [n = 31]) and NIDDM patients without retinopathy (0.30 +/- 0.05 pM [n = 9]). CONCLUSIONS: These results suggest that plasma ET-1 is related to diabetic microvascular disease.

Biomarkers↗

PubMed1992

Endothelin-specific antibodies decrease blood pressure and increase glomerular filtration rate and renal plasma flow in spontaneously hypertensive rats.

OBJECTIVE: Studies were undertaken to clarify the pathophysiologic significance of endogenous endothelin in the control of blood pressure and renal hemodynamics in spontaneously hypertensive rats (SHR). DESIGN: The technique of passive immunization was used to neutralize endogenous endothelin in order to estimate the contribution of endothelin to the in vivo control of blood pressure and renal hemodynamics. METHODS: Endothelin-specific antibodies were administered intravenously into anesthetized SHR and Wistar-Kyoto (WKY) rats, and the effects upon blood pressure and renal function (renal plasma flow and glomerular filtration rate) assessed. Using the same antibodies, baseline plasma levels of endothelin in both strains of rats were determined by radioimmunoassay. RESULTS: Infusion of endothelin-specific antibodies into SHR decreased mean arterial pressure by approximately 10% and renal vascular resistance and renal vascular resistance by approximately 35%. Glomerular filtration rate and renal plasma flow both increased by approximately 50% over control. In contrast, infusion of normal rabbit serum into SHR or of endothelin-specific antibodies into WKY rats did not result in any significant change in renal hemodynamics or arterial blood pressure. Baseline plasma levels of immunoreactive endothelin in SHR were significantly lower than those in WKY rats. CONCLUSION: These results suggest that endothelin plays an important role in the modulation of systemic blood pressure and renal function in SHR.

Animals↗

PubMed1992

[A randomized study of pirarubicin (THP) versus adriamycin (ADM) for intravesical instillation therapy against superficial bladder cancer].

To determine the antitumor action by intravesical instillation prior to transurethral resection TUR, a randomized study on pirarubicin (THP) versus adriamycin (ADM) was performed for superficial, papillary and initially detected bladder cancers with participation of 21 Urological Clinics in 3 Tokai Prefectures. The instillation dose of 500 micrograms/ml was given 3 times per week for 3 weeks in both THP (n = 33) and ADM (n = 30) groups. The complete and partial response rates were 56.3% in THP group and 26.7% in ADM group. THP instillation was more effective against multiple tumors than a single tumor, stage Ta than T1 and grade G1 than G2 and G3. However, these findings were not statistically significant. Untoward effects were mainly bladder irritability and its frequency was 60.6% in the THP group and 23.3% in the ADM group. Contracted bladder was found in 2 of the 33 patients in the THP group and 2 of the 30 patients in the ADM group. The antitumor effect of a half dose of THP was equivalent to that of one dose of ADM, and the THP group showed a twofold higher frequency of side effects. Therefore, a clinical trial should be made comparing the effect of 500 micrograms/ml of THP and that of 1,000 micrograms/ml of ADM.

Administration, Intravesical↗

PubMed1991

Atrial natriuretic peptide and brain natriuretic peptide coexist in the secretory granules of human cardiac myocytes.

To elucidate the intracellular localization of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in human cardiac myocytes, an immunocytochemical study was carried out by a double immunogold technique using antisera highly specific for ANP and BNP. Surgical and autoptic tissue specimens of human heart were studied. In the atrial myocytes, ANP was localized in almost all of the secretory granules, whereas BNP was colocalized with ANP in some of the granules. Although very few secretory granules were observed in ventricular myocytes, colocalization of ANP and BNP was basically the same as in atrial myocytes. No immunoreactive products were found in the control studies. These results suggest that secretion of BNP is under a regulatory mechanism similar to that of ANP.

Atrial Natriuretic Factor↗

PubMed1991

Immunoreactive endothelin in plasma of nonmammalian vertebrates.

Immunoreactive endothelin (ir-ET) was estimated in plasma of nonmammalian vertebrates, using radioimmunoassay (RIA) for endothelin-1 (ET-1). Blood samples were collected from unanesthetized animals. Plasma ET was determined by RIA after extraction. Plasma levels of ir-ET were 0.7 +/- 0.2 pg/ml (n = 6) in the hagfish Eptatretus burgeri, 4.3 +/- 0.9 pg/ml (n = 5) in the banded dogfish Triakis scyllia, 3.6 +/- 0.8 pg/ml (n = 3) in the common Japanese conger Conger myriaster, 9.6 +/- 1.4 pg/ml (n = 7) in the carp Cyprinus carpio, 6.4 +/- 0.8 pg/ml (n = 5) in the bullfrog Rana catesbeiana, 6.7 +/- 0.6 pg/ml (n = 3) in the soft-shelled turtle Trionyx sinensis japonica, and 3.3 +/- 0.6 pg/ml (n = 8) in the Japanese quail Coturnix coturnix japonica. The dilution curves of the plasma extracts from each species almost paralleled the standard curve for ET-1. Analysis of the plasma extracts of the carp by reverse-phase high-performance liquid chromatography revealed that ir-ET consisted of three components, a predominant peak being located at the elution position of synthetic ET-1. The present results demonstrate clearly that an ET-1-like substance circulates in blood of nonmammalian vertebrates, suggesting an endocrine function of the peptide in these species.

Animals↗

PubMed1991

Plasma immunoreactive endothelin, but not thrombomodulin, is increased in patients with essential hypertension and ischemic heart disease.

To ascertain an involvement of vascular endothelial cells in cardiovascular disease, we have determined plasma levels of two endothelium-derived substances, endothelin (ET) and thrombomodulin (TM), in essential hypertension (EH) and ischemic heart disease. Plasma ET was determined by radioimmunoassay (RIA) after extraction. Plasma TM levels were determined by enzymunoimmunoassay. Plasma ET levels were significantly elevated in patients with EH involving target organ damage, vasospastic angina pectoris (VSA), and acute myocardial infarction (AMI), especially in those associated with cardiogenic shock. There was a weak but significant correlation between plasma ET levels and serum creatinine concentration in patients with EH. Plasma ET levels were elevated even before the coronary spasm in patients with VSA, whereas they did not show any further increase during the spasm. In contrast, plasma TM levels in patients with EH and VSA did not show a significant difference from that in normal subjects. These results suggest that ET plays an important role in the pathophysiology of EH and ischemic heart disease, and also that increases in plasma ET cannot be simply attributed to a leakage of the peptide from the injured endothelial cells.

Angina Pectoris↗

PubMed1991

Is big endothelin converted to endothelin-1 in circulating blood?

Although evidence has been accumulating to support an intracellular processing of big endothelin-1 (big ET-1) to ET-1, molecular conversion in the circulating blood remains to be elucidated. The present study was undertaken to investigate whether big ET-1 was converted to ET-1 in human blood. In the first experiment, normal serum with synthetic big ET-1 exogenously added or serum from patients with chronic renal failure was incubated in vitro at 37 degrees C for 1 h. In the second experiment, synthetic big ET-1 was incubated in the whole blood at 37 degrees C for 1 h. In the third experiment, synthetic big ET-1 was administered intravenously in anesthetized rat and a plasma sample was obtained before and after 15 min and 1 h. After respective incubation, molecular forms of ET were determined by a combination of reverse-phase high-performance liquid chromatography and radioimmunoassay. There was no significant conversion of big ET-1 to ET-1 in the serum obtained from normal and CRF patients. However, there was a slight but significant increase of ET-1 after incubation of big ET-1 in the whole blood or after administration of big ET-1 in anesthetized rat. The conversion in the whole blood was inhibited by 5 mM EDTA. These results suggest that circulating blood may not be a major site of molecular conversion from big ET-1 to ET-1, although conversion does occur in the circulation by blood cell-mediated process.

Animals↗

PubMed1991

Molecular form of immunoreactive endothelin in plasma and urine of normal subjects and patients with various disease states.

To elucidate the pathophysiologic significance of the family of endothelin (ET) peptides, we have investigated plasma and urinary immunoreactive (ir-) ET levels and its molecular forms in normal and pathological conditions. Plasma and urine ET were extracted with an Amprep C2 column. The molecular form of ET was determined by a combination of radioimmunoassay and reverse-phase high-performance liquid chromatography. Although plasma ir-ET was composed mainly of big ET and endothelin-1 (ET-1) in normal subjects, that in acute myocardial infarction, chronic renal failure (CRF), essential hypertension, and vasospastic angina pectoris was characterized by an increase of high molecular ir-ET in addition to increases in big ET and ET-1. Urinary ir-ET in both normal subjects and patients with CRF was composed mainly of a high molecular form in addition to big ET and ET-1. These results suggest that the biosynthetic and/or degradation process of ET under pathological conditions appears to be different from that under normal conditions.

Angina Pectoris↗

PubMed1991

Relationship between fetal hypoxia and endothelin-1 in fetal circulation.

The role of endothelin-1 (ET-1), a potent vasoconstrictor peptide secreted by endothelial cells, in fetal circulation was investigated in relation to fetal hypoxia. Umbilical venous blood was obtained from 23 subjects who delivered between 36 and 41 weeks of gestation. In all cases, pH of umbilical venous blood was measured immediately after the delivery of placenta. ET-1 was extracted from the umbilical venous plasma by an Amprep C2 column and determined by a specific radioimmunoassay. Immunoreactive ET levels in the umbilical cord plasma (pg/ml, mean +/- SEM) from subjects with umbilical venous blood pH levels below 7.30 (n = 9) were 12.53 +/- 2.03, significantly higher than those with pH levels above 7.30 (6.44 +/- 1.11, n = 14). These results indicate that ET-1 in the fetal circulation may be involved in the regulation of the circulation in response to changes in acid-base balance related to fetal hypoxia.

Adult↗

PubMed1991

Antiserum against homologous atrial natriuretic peptide diminishes the natriuretic response during mineralocorticoid escape in rats.

To elucidate the physiological role of atrial natriuretic peptide (ANP) in plasma during mineralocorticoid escape, we investigated the effects of passive immunization with ANP-specific antiserum on deoxycorticosterone (DOCA)-treated rats. Sodium was retained in excess of intake during the first day after treatment with DOCA, and sodium balance returned to control values by the second day, whereas the excretion of potassium exceeded the intake during all days after DOCA treatment. These changes in electrolyte balance were associated with a significant increase in plasma levels of ANP. Administration of ANP-specific antiserum significantly impaired the return to normal sodium balance as well as the augmented kaliuresis that were observed on the second day after injection of DOCA. No significant effect was observed on either sodium or potassium balance after the injection of normal rabbit serum. These results suggest that plasma ANP plays an important role in mineralocorticoid escape.

Animals↗

PubMed1991

Electrophysiological analysis of structural aspects of voltage-dependent SR K+ channel.

This article presents a brief review on the electrophysiological analysis of the structural aspects of the voltage-dependent SR (sarcoplasmic reticulum) K+ channel. In the first half, early attempts to determine the physical dimensions of the ion conducting mechanism such as the mouth, narrow tunnel, or ion selective filter of the channel, are reviewed. The depicted cartoon of the SR K+ channel, as an extremely short, busy district with a big mouth on each side, is quite similar to the recently-obtained reconstructed structural image of the acetylcholine receptor channel. In the latter half, we introduce our recent attempts to draw a physical image of the gating mechanism of the SR K+ channel. We examined, for example, the location of the gate and the voltage sensor, and the relationship between them. It is suggested that the gate and the sensor are connected tightly and that the sensor would be exposed to the surface of the lumen side of SR when the gate opens. Finally, the issue of substates in SR K+ channel is discussed. It is implied that the substrate-conductances reflect a partial occlusion of the pore by an intermediate-open gate.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1990

Immunocytochemical localization of endothelin in cultured bovine endothelial cells.

To investigate the intracellular localization of endothelin in cultured endothelial cells, an immunocytochemical study was carried out by the post-embedding protein A-gold technique with endothelin-specific antiserum. Gold particles were seen on the rough endoplasmic reticulum, the Golgi cisternae, the Golgi vesicles, small vesicles beneath the cell membrane, and the lysosomes. By contrast, no secretory granules were observed. These results suggest that endothelin is secreted by a constitutive pathway and that the lysosome may play an important role in regulating the biological activity of endothelin.

Animals↗