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T Katafuchi

Publications and source records attributed to T Katafuchi.

At least 73 records · Page 4Linked to original sources
PubMed1991

Kappa-opioid antagonist strongly attenuates drinking of genetically polydipsic mice.

Effects of opioid antagonists on the genetic polydipsia of the STR/N strain of mice were investigated. Naltrexone (0.5-5.0 mg/kg) injected subcutaneously before dark period attenuated spontaneous drinking for the first 3 h after injection only in the inbred polydipsic mice (STR/N), whose water intake was 5 times that of controls (non-polydipsic mutant, STR/1N, and Swiss/Webster mice). The highest dose (5 mg/kg) of naltrexone administration reduced drinking also during the next 3-6 h period and overnight feeding. Cerebroventricular (i.c.v.) injection of naltrexone, 1.0 and 2.5 micrograms (per mouse), suppressed drinking only in the polydipsic mice, while the higher dose (5.0 micrograms) attenuated drinking and feeding of both the polydipsic mice and their controls. However, i.c.v. injection of specific kappa-receptor antagonist, nor-binaltorphimine (nor-BNI, 0.5-2.5 micrograms), suppressed drinking only in the polydipsic strain of mice at one-half dose of that needed for naltrexone. Furthermore, even a higher dose of nor-BNI administration was without effect on food intake in all strains. These findings suggest that the central opioid system plays an important role in causing the polydipsia in the STR/N mice, probably through the kappa-opioid receptor.

Animals↗
PubMed1991

Characterization of opioid-sensitive neurons in the anteroventral third ventricle region of polydipsic inbred mice in vitro.

In previous studies we found that in the extremely polydipsic special strain of mice, STR/N, spontaneous drinking was greatly attenuated by injection of the opioid antagonists given intracerebroventricularly as well as subcutaneously. Therefore, we investigated, using hypothalamic slice preparations, responses of neurons in the anteroventral third ventricle region (AV3V) of the STR/N and its control, Swiss/Webster (S/W) mice to morphine and opiate peptides. An application of morphine at 10(-6) M to the circulating medium inhibited activities of 44% of AV3V neurons (45 of 102) in the STR/N, and 59% (76/129) in the S/W, demonstrating that morphine affected a smaller proportion of neurons of the polydipsic mice than that of controls. Opioid agonists for 3 receptor types, mu, delta and kappa, at 10(-6) to 10(-5) M inhibited AV3V neurons in both the STR/N and S/W mice, but to a different degree. No cell of either strain was excited by morphine or any of the opioids. The mu-receptor agonist, [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAGO), was the most potent inhibitor of AV3V neurons; in the STR/N 53% (25/47), and in the S/W 77% (34/44) were inhibited. The kappa-agonist, dynorphin A-(1-13) (DYN), inhibited fewer cells in the STR/N (9%, 4/47), compared with the S/W (36%, 16/44). Only a few cells responded to the delta-agonist, [D-Pen2,5]enkephalin (DPDPE), in both strains. The inhibitory actions of the opiates were reversibly blocked by naloxone, and persisted under synaptic blockade. The threshold concentration of morphine or DAGO for inhibition of AV3V neurons was higher in the STR/N (approximately 10(-8) M for both morphine and DAGO) than in S/W mice (approximately 10(-9) M for morphine and less than 10(-9) M for DAGO). Although the AV3V also contains angiotensin II-sensitive neurons, they were not affected by morphine (10(-6) M). Similarly neurons inhibited by morphine were not excited by angiotensin II (10(-7) M); some neurons were unresponsive to both chemicals. We conclude that morphine and opiate peptides directly inhibit the AV3V neurons of both the STR/N and S/W strains of mice and the sensitivity of these neurons to the opiates is lower in the polydipsic inbred mice compared to their controls. The results, together with our behavioral studies, suggest involvement of the central opioid system in the polydipsia of the STR/N mice.

Angiotensin II↗
PubMed1991

Bifunctional atrial natriuretic peptide receptor (type A) exists as a disulfide-linked tetramer in plasma membranes of bovine adrenal cortex.

Type A atrial natriuretic peptide (ANP) receptor was demonstrated to be present as a tetramer in the bovine adrenal cortex. Type A ANP receptor is composed of two functional domains, namely extracellular ANP-binding and cytoplasmic guanylate cyclase domains, and generally considered to be present as a single polypeptide chain of about 140 kDa based on its primary structure deduced from the cDNA sequence and its SDS/PAGE profile under reducing conditions. Characterization of the type A receptor or receptor/cyclase under non-reducing conditions led to the discovery stated in the title. The type A ANP receptor was partially purified from bovine adrenal cortex membranes by Blue-Sepharose and GTP-agarose chromatography. SDS-PAGE analysis of the receptor preparation revealed that although under reducing conditions it migrated as a 140-kDa band, the mobility of the receptor was greatly retarded in the absence of reducing agents, suggesting that the type A ANP receptor is present as a disulfide-linked oligomer in its native state. Further analysis using SDS-polyacrylamide-agarose gels suitable for determining the sizes of high-molecular-weight proteins revealed that the oligomer has an Mr of 500,000-550,000. This result clearly indicates that the native form of the type A receptor is a tetramer composed of four 140-kDa disulfide-linked receptor/cyclase molecules.

Adrenal Cortex↗
PubMed1991

Involvement of angiotensin II in water intake of genetically polydipsic mice.

The involvement of angiotensin II (ANG II) in the genetic polydipsia of the STR/N strain of mice was investigated. Daily water intake of the polydipsic inbred STR/N of both sexes ranged between five and eight times that of nonpolydipsic controls: STR/1N, a mutant of the STR/N, and Swiss-Webster (S/W) mice. Nevertheless the diurnal pattern of drinking was maintained in the STR/N. There was no difference in daily food intake, arterial blood pressure, and plasma renin activity among the three groups. Drinking responses to 48 h of water deprivation were not significantly different between the polydipsic mice and their control groups. Captopril, an angiotensin I converting-enzyme inhibitor, injected subcutaneously just before the dark period, reduced drinking for 6 h in the polydipsic strain only. Food intake of all three groups of mice was not affected. Similarly the ANG II antagonist saralasin, [Sar1,-Ile8]ANG II, injected into the lateral cerebroventricle just before the dark period, significantly reduced water intake for 6 h after injection in the polydipsic mice only. Intracerebroventricular injection of ANG II increased drinking in the nondeprived controls but not in the polydipsic mice. These findings suggest that the polydipsia in the STR/N mice may involve, at least in part, the ANG II system in the brain.

Angiotensin II↗
PubMed1991

[Quantitative evaluation of myocardial viability using Tl-201 myocardial SPECT].

In order to evaluate myocardial viability, we developed a new method for quantification of redistributed area in Tl-201 myocardial SPECT, and it was applied to 71 patients with LAD lesion. Initial image was subtracted from delayed image, and redistributed area was displayed as an unfolded map (viability map). Extent and viability score, which correspond to extent and degree of the viable area, was also calculated. In the cases with prior myocardial infarction, viability score was widely distributed and extent score was smaller, while the cases with angina pectoris had larger extent score. Visual assessment of redistribution to the infarcted area was compared with % score, which was calculated as ratio to initial defect score. When the criteria of viability was defined as % viability score greater than 36 or % extent score greater than 16, quantitative evaluation agreed with visual assessment, and corresponded to clinical course. This method was considered to be effective for evaluation of extent and degree of myocardial viability, but further evaluation need to be done in comparison with reinjection, PET study, and so on, and usefulness in multi-vessel disease.

Adult↗
PubMed1990

Human adrenal tumor cell line SW-13 contains a natriuretic peptide receptor system that responds preferentially to ANP among various natriuretic peptides.

A new type of ANP receptor system which clearly distinguishes natriuretic peptides A and B (ANP and BNP) has been identified in the human adrenal tumor cell line SW-13 and characterized. SW-13 cells responded to nanomolar concentrations of ANP with large increases in cGMP levels but in the case of BNP, much higher concentrations were required to produce the same extent of response. This property is unique since the 140-kDa ANP receptors so far characterized do not discriminate between ANP and BNP. For comparison, various natriuretic peptide receptors were also re-characterized using the recently identified CNP.

Adrenal Gland Neoplasms↗
PubMed1990

Fastigial inputs to paraventricular neurosecretory neurones studied by extra- and intracellular recordings in rats.

1. The effects of stimulation of the cerebellar fastigial nucleus (FN) on the activity of neurosecretory neurones in the hypothalamic paraventricular nucleus (PVN) of rats, anaesthetized with urethane and alpha-chloralose, were investigated by extracellular and intracellular recordings. 2. With extracellular recording, 139 PVN neurosecretory neurones were identified by antidromic activation following stimulation of the pituitary stalk, of which 120 were spontaneously firing and 19 were silent. Three types of responses to FN stimulation (1 or 2 pulses at 333 Hz) were observed in 43% of spontaneously firing PVN neurosecretory neurones: inhibition (type I) with a latency of 4.3 +/- 4.1 ms (mean +/- S.D., 32 of 120 neurones, 27%); excitation (type E) with 22.3 +/- 8.1 ms latency (14 of 120, 11%); and inhibition-excitation type (I-E) with 5.5 +/- 3.4 ms latency (6 of 120, 5%). Silent neurosecretory neurones did not respond to FN stimulation. Twelve per cent of non-neurosecretory cells (three out of twenty-six tested) responded to FN stimulation (one was inhibited, and two were excited). 3. Repetitive stimulation (60 Hz, 10 s) of the FN, which evoked a stimulus-locked pressor response, suppressed on-going activity of PVN neurosecretory neurones in 43% (twenty-nine of sixty-eight) of neurones tested. In 40% of these neurones, the activity was also inhibited by intravenous injection of phenylephrine (3 micrograms in 0.3 ml Ringer solution), while in other neurones the injection had no effect. Rebound excitation of neurone activity lasting for 1-5 min after termination of repetitive stimulation was observed in 28% of the neurones. Ten neurones (14%) were excited by repetitive stimulation. 4. Successful intracellular recordings were made from seventy-two PVN neurones, of which thirty-seven were neurosecretory cells. The mean resting membrane potential was -51 mV (n = 72; range from -40 to -75 mV). The input resistance of neurosecretory cells was 117 +/- 21 M omega (range 93-153 M omega; n = 8). This value was higher than that for non-neurosecretory cells which was found to be 53 +/- 10 M omega (range 35-72 M omega; n = 9). The difference was statistically significant (P less than 0.01, Student's t test). 5. In response to FN stimulation, sixteen (43%) of the thirty-seven neurosecretory neurones showed IPSPs with latencies of 7.4 +/- 2.8 ms and three (8%) exhibited EPSPs with latencies of 13.3 +/- 4.2 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1990

[Unfolded map of coronary artery territories by myocardial SPECT].

Coronary artery territories were evaluated precisely by Bull's-eye and unfolded map generated from myocardial SPECT. In addition, unfolded maps including apical information were also developed. The coronary artery territories were determined by 54 cases of typical single vessel disease (more than 75% stenosis) with myocardial infarction and angina pectoris. There were 12 of right coronary artery disease, 24 of left anterior descending coronary artery disease, 5 of diagonal coronary artery disease, and 13 of left circumflex artery disease. Each diseased region was summed and normalized using the standard pattern (21 cases of normal male and 13 cases of normal female). Apical information was simply obtained using the anterior and posterior count from short and long axial image. Then, their data were added to the unfolded map. In conclusion, unfolded map was proven to be useful for the determination of coronary artery territory, since this map expressed the extent and site of myocardial damage precisely compared to Bull's-eye. The unfolded map to contain the apical information was also useful for the evaluation of left anterior descending coronary artery involvement.

Coronary Disease↗
PubMed1990

[Clinical evaluation of coronary territory map by using unfolded map of Tl-201 myocardial SPECT].

Coronary territory map was developed on unfolded map of exercise Tl-201 myocardial SPECT. Each coronary territory was determined by summing the each unfolded map of 54 cases of single vessel disease respectively, and standardizing with normal pattern obtained from normal patients. The diagnostic accuracy of coronary territory map to identify the diseased coronary artery was analyzed in 104 clinical cases and was compared with that of planar and SPECT visual diagnosis, simple unfolded map (raw map) and extent & severity map. The results were as follows; 1) Territory map showed excellent diagnostic accuracy in single or double vessel disease, especially in diagnosis of left circumflex coronary artery lesion. 2) In triple vessel disease, the diagnostic accuracy of territory map or other unfolded maps was 30% at best, and was inferior to planar or SPECT visual analysis. The cause of this inferiority seemed that the quantitatively analyzed map had no information about the degree of Tl-uptake into lung or myocardium, which give useful information in visual diagnosis. 3) The diagnostic agreement ratio in two observers was the highest in territory map diagnosis, so that the territory map diagnosis seemed to be the most objective one. 4) The unfolded map diagnosis with apical display obtained from long-axis tomogram was useful to diagnose left anterior descending coronary (LAD) lesion, which improve not only the sensitivity of LAD but also specificity of right coronary artery single vessel disease.

Coronary Disease↗
PubMed1989

Responses of rat lateral hypothalamic neuronal activity to fastigial nucleus stimulation.

1. The aim of this study was investigation of neuronal mechanisms underlying inputs from the fastigial nucleus (FN) to the lateral hypothalamic area (LHA). 2. In male anesthetized rats, 295 extracellular and 82 intracellular recordings of LHA responses to electrical stimulation of the FN, which elicited stimulus-locked pressor responses, were examined. 3. Contralateral FN stimulation evoked three types of responses in 48% of spontaneously firing LHA neurons: inhibition with 11 +/- 6 (SD) ms latency followed by excitation (30%), excitation with 15 +/- 12.5 ms latency (14%), and excitation followed by inhibition with 6 +/- 4 ms latency (4%). 4. Contralateral FN stimulation after transection of the inferior cerebellar peduncle (ICP), which resulted in a substantial fall of the fastigial pressor response, also evoked the three types of responses. These responses were unaffected by transection of the ICP. 5. Neuronal activity was recorded intracellularly from 82 LHA neurons, of which 36 (44%) responded to FN stimulation. Of the 36 neurons, 24 showed inhibitory postsynaptic potentials (IPSPs) with a mean latency of 7.5 +/- 2 ms. Of the 24 neurons, 16 were checked for change in IPSP latency with stimulus intensity, and 11 were considered to be monosynaptically connected since their latencies were constant when FN stimulation intensity was changed. The remaining 12 exhibited excitatory postsynaptic potentials (EPSPs) with a longer latency of 10.5 +/- 3 ms, which indicated polysynaptic conduction. The reversal potentials of the IPSP and EPSP were estimated to be about -77 mV and -13 mV, respectively. 6. Most glucose-sensitive neurons (78%), which were identified by their inhibition in response to electrophoretically applied glucose, were inhibited by FN stimulation, whereas only 7% of the glucose-insensitive neurons responded to such stimulation. 7. From the results, it was concluded that LHA neurons receive inhibitory monosynaptic and excitatory polysynaptic inputs from the FN via the superior cerebellar peduncle. These connections may contribute to hypothalamic modulation of feeding behavior.

Animals↗
PubMed1988

Effects of chemical stimulation of paraventricular nucleus on adrenal and renal nerve activity in rats.

The effects of stimulation of the hypothalamic paraventricular nucleus (PVN) by L-glutamate on blood pressure and ongoing activities of adrenal and renal sympathetic nerves were examined in anesthetized rats. Microinjection of excitatory amino acid, L-glutamate (100 nmol in 200 nl saline), into the unilateral PVN resulted in an increase in the ipsilateral adrenal nerve activity, while it resulted in decreases in renal nerve activity and arterial blood pressure. After severance of bilateral carotid sinus and vagal nerves, the decreased response of blood pressure to the same stimulus did not change, while the decreased response of renal nerve activity was almost abolished, and the increased response of adrenal nerve activity still remained, though it slightly attenuated. The involvements of baroreceptor afferents and vagal afferents in these responses were discussed.

Action Potentials↗
PubMed1988

Lateral and ventromedial hypothalamic influences on hepatic autonomic nerve activity in the rat.

Effects of hypothalamic stimulation and lesion on hepatic autonomic nerve activity were investigated in anesthetized rats. Stimulation of the lateral hypothalamic area increased activity of the hepatic vagal nerve and decreased activity of the splanchnic nerve. Lesion of this area produced a rapid and strong reduction of vagal nerve activity and induced either an increase or a decrease of splanchnic nerve activity. In contrast, stimulation of the ventromedial hypothalamic nucleus produced a strong inhibition of vagal nerve activity and facilitation of splanchnic nerve activity. However, lesion of this nucleus facilitated or inhibited activities in both nerve branches. The functional significance of the relationship between the hypothalamus and the hepatic autonomic nerve in regulation of glucose metabolism in the liver are discussed.

Animals↗
PubMed1987

Single neuron activity of rat hypothalamic paraventricular nucleus during body suspension.

Single neuron activity in the hypothalamic paraventricular nucleus (PVN) was recorded during horizontal and 45 degrees head-down tilt suspension in unanesthetized rats. When the rats were raised in the head-down position, 13 of 34 neurons (38%) in the PVN changed activity as follows: gradual decrease (11/13, type I), or gradual increase (2/13, type II). Responses of 6 type I and 1 type II neuron were smaller during horizontal suspension. Intracerebroventricular or intraperitoneal injection of hypertonic saline caused an increase in activity of 4 of 5 type I neurons tested. This hyperosmotic stimulation had no effect during suppressed activity induced by head-down tilt. These results suggest that the activity of PVN neurons is altered during body suspension, probably by information from baroreceptors in the thoracic activity, proprioreceptors and/or the vestibular organ, and these neurons might be involved in regulation of the autonomic and neuroendocrine systems.

Action Potentials↗
PubMed1987

Responses of rat lateral hypothalamic neuron activity to vestibular nuclei stimulation.

Effects of lateral vestibular nucleus (LVN) stimulation on neuronal activity in the rat lateral hypothalamic area (LHA), including specific glucose-sensitive neurons, were investigated by extracellular and intracellular recordings in vivo. Stimulation of the contralateral LVN evoked 3 types of response in 46% (111/240) of the neurons recorded extracellularly: long latency (38.1 +/- 23.6 ms) excitation (62/111, 56%), short latency (6.9 +/- 3.1 ms) excitation-inhibition (33/111, 30%), and inhibition with 20.1 +/- 11.1 ms latency (16/111, 14%). Glucose-sensitive neurons, which were identified by electrophoretic application of glucose, did not respond specifically to such stimulation. Neuronal activity was recorded intracellularly from 31 LHA neurons, of which 13 responded to LVN stimulation. Seven of the 13 neurons showed a long latency EPSP (10.4 +/- 5.5 ms) and the remaining 6 exhibited an EPSP-IPSP sequence with shorter latency (4.5 +/- 3.0 ms). The amplitude of these responses was graded with a change in stimulus intensity. The EPSPs of both types of response were considered to be polysynaptic because of shortening of latencies by higher current stimulation. Since the LHA is implicated in the regulation of autonomic nerve activity, the present results showing polysynaptic pathways from the LVN to the LHA suggest functional involvement of the LHA in vestibulo-autonomic responses.

Animals↗
PubMed1987

Basic imaging properties of a large image intensifier-TV digital chest radiographic system.

The basic imaging properties of a large (57 cm) image intensifier (I.I.)-TV digital imaging system were examined to determine the effects of various physical parameters on the quality of the digital chest images obtained, and also to explore the clinical usefulness of the system. The characteristic curve of the digital system, which relates the output pixel value to the input relative x-ray intensity, was measured with an aluminum stepwedge. MTFs were determined using slit images, and the veiling-glare fraction was measured with a lead-disk technique. Noise Wiener spectra were obtained from uniformly exposed images. The current limitations of the large II-TV digital chest system are its low spatial resolution, and the presence of large amounts of veiling glare and structure mottle. Advantages of this system over other digital chest imaging systems include the high speed of image data acquisition and the capability of "real-time" dynamic imaging of the chest at a radiation dose comparable to that in conventional radiography of the chest.

Humans↗
PubMed1987

Hypothalamus and sodium-potassium pump activity in skeletal muscles of DOCA-hypertensive rats.

The effects of hypothalamic lesions on Na+ and K+ content ([Na+]i and [K+]i) in both slow tonic muscle [soleus (SOL)] and fast-twitch muscle [extensor digitorum longus (EDL)] were investigated in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. In DOCA-treated rats, [Na+]i was increased and [K+]i decreased in both SOL and EDL muscles compared with controls. Cellular K+ loss and Na+ accumulation in SOL were restored after tibial nerve sectioning (delta [Na+]i, -14.2 +/- 2.6 and delta [K+]i, 13.9 +/- 2.6 mmol/l fiber water (FW), n = 18, P less than 0.01) or bilateral lesioning of the ventromedial hypothalamic nucleus (VMH) (delta [Na+]i, -15.5 +/- 1.5 and delta [K+]i, 17.4 +/- 4.6 mmol/l FW, n = 6, P less than 0.01 and P less than 0.05). On the other hand, the anomalous electrolyte content in EDL was counteracted by lesions of anteroventral portion of the third ventricle (AV3V) (delta [Na+]i, -8.8 +/- 1.6 and delta [K+]i, 5.2 +/- 1.2 mmol/l FW, n = 6, P less than 0.01 and P less than 0.05) or paraventricular hypothalamic nucleus (PVN) (delta [Na+]i, -6.8 +/- 0.6 and 5.7 +/- 1.2 mmol/l FW, n = 6, P less than 0.01 and P less than 0.05), but aggravated by denervation (delta [Na+]i, 13.4 +/- 1.8 and delta [K+]i, -9.6 +/- 1.8 mmol/l FW, n = 18, P less than 0.01). These results suggest that there are at least two hypothalamic mechanisms of suppression of muscle Na-K pump activity in DOCA-hypertensive rats; i.e., neurally mediated inhibition in SOL by the VMH and, presumably, humorally mediated inhibition originating from the AV3V or PVN with greater influence in EDL.

Animals↗
PubMed1987

Effects of hypothalamic stimulation and lesion on adrenal nerve activity.

Activity changes of efferent adrenal sympathetic nerves in response to bilateral manipulations of the hypothalamus, partly after intra-third cerebroventricular injection of 2-deoxy-D-glucose (2-DG) were investigated in anesthetized rats. Stimulation of the middle part of the lateral hypothalamic area (LHAm) increased adrenal nerve activity, whereas lesion caused rapid and remarkable decrease. Stimulation of the anterior part of the LHA (LHAa) tended to decrease the activity, and lesion produced either rapid decrease or late moderate increase. Stimulation of the ventromedial hypothalamic nucleus (VMH) did not affect the nerve activity, but lesion increased it gradually and then remarkably. Cerebroventricular infusion of 2-DG caused remarkable increase in activity that was suppressed by LHAm lesion. Subsequent infusion of 2-DG during the period of suppressed activity was no longer effective. The increased firing rate after 2-DG was suppressed by stimulation of the VMH, whereas lesion caused no change. These findings indicate that the central regulation of adrenal nerve activity is connected with individual hypothalamic regions and consequently depends on the degree and mode of activation of the sympathoadrenal system.

Action Potentials↗