Search PubMed⌕ Search

Biomedical subjects

M Sakamoto

Publications and source records attributed to M Sakamoto.

At least 703 records · Page 39Linked to original sources
PubMed1986

The lung as a possible target organ for atrial natriuretic polypeptide secreted from the heart.

Using a specific radioimmunoassay (RIA) for alpha-rat atrial natriuretic polypeptide (alpha-rANP), we have demonstrated the presence of a considerable amount (6.10 +/- 0.38 ng/g) (mean +/- SE) of alpha-rANP-like immunoreactivity (alpha-rANP-LI) in the rat lung, the first organ through which atrial natriuretic polypeptide (ANP) released from the heart passes. High performance gel permeation chromatography coupled with the RIA revealed that most of alpha-rANP-LI eluted at the position of a low molecular weight form corresponding to synthetic alpha-rANP. In 2- or 5-day water-deprived rats, the concentration and content of alpha-rANP-LI in the lung decreased significantly compared with those of control rats. In addition, water-deprivation induced a significant decrease in the plasma concentration of alpha-rANP-LI simultaneously determined. There was a significant positive correlation between the concentrations of alpha-rANP-LI in the lung and plasma (r = 0.591, P less than 0.01). These results indicate the presence of ANP in the lung and suggest physiological roles of ANP in pulmonary function.

Animals↗
PubMed1986

Decreased content in left atrium and increased plasma concentration of atrial natriuretic polypeptide in spontaneously hypertensive rats (SHR) and SHR stroke-prone.

The atrial contents and concentrations, and the plasma concentrations of atrial natriuretic polypeptide (ANP) in spontaneously hypertensive rats (SHR) and SHR stroke-prone (SHRSP) were measured and compared with those of age-matched Wistar Kyoto rats (WKY) using a specific radioimmunoassay (RIA) for alpha-rat ANP (alpha-rANP). The contents of alpha-rANP-LI in the atria of SHR (19.0 +/- 0.9 micrograms, mean +/- SEM) and SHRSP (19.3 +/- 0.6 micrograms) were significantly lower than that of WKY (22.8 +/- 1.4 micrograms) (p less than 0.05). The atrial concentration of alpha-rANP-LI was also significantly lower in SHR (248.2 +/- 11.3 ng/mg, p less than 0.05) and tended to be lower in SHRSP (272.2 +/- 12.4 ng/mg) than that of WKY (300.0 +/- 14.2 ng/mg). Furthermore, the concentrations in the left auricles of SHR and SHRSP were significantly lower than that of WKY (p less than 0.01 and p less than 0.05, respectively). In contrast, no significant difference was observed in the alpha-rANP-LI concentrations in the right auricles of WKY, SHR and SHRSP. Gel filtration studies coupled with RIA showed that gel filtration profiles of the extracts from the right and left auricles of WKY, SHR and SHRSP were essentially identical. The plasma alpha-rANP-LI levels in SHR (260 +/- 34 pg/ml) and SHRSP (319 +/- 19 pg/ml) were significantly higher than that in WKY (170 +/- 17 pg/ml) (p less than 0.05 and p less than 0.01, respectively). These results suggest that the secretion of ANP from the heart is increased in SHR and SHRSP compared with WKY.

Animals↗
PubMed1986

Cell activity in monkey caudate nucleus preceding saccadic eye movements.

Single cell activity was recorded in the monkey caudate nucleus. The monkey fixated a visual target, and, if the target jumped, followed it by making a saccade. A group of cells showed spike discharges before a contralateral saccade to the target. This activity was related to the saccade rather than the onset of the target, but was conditional in that it was unrelated to spontaneous saccades which were made without a particular target. Some caudate cells showed activity only when the saccade was made to a remembered position of a target. It is suggested that caudate cells contribute to the initiation of saccades in a selective manner by removing nigro-collicular tonic inhibition.

Animals↗
PubMed1986

The pharmacokinetics of alpha-human atrial natriuretic polypeptide in healthy subjects.

We have analysed the pharmacokinetics of alpha-human atrial natriuretic polypeptide (alpha-hANP) in healthy subjects, using a two-compartment open model following bolus intravenous injection. The plasma half-times for the fast and slow components were 1.7 +/- 0.07 min and 13.3 +/- 1.69 min respectively. V1 (the volume of the central compartment), VZ (volume of distribution) and VSS (volume of distribution at steady-state) were 5370 +/- 855 ml (89.5 +/- 14.3 ml X kg-1), 32000 +/- 4620 ml (533 +/- 77.0 ml X kg-1), and 11900 +/- 1530 ml (198 +/- 25.5 ml X kg-1) respectively. The mean plasma clearance was 1520 +/- 121 ml X min-1 (25.4 +/- 2.0 ml X min-1 X kg-1.

Adult↗
PubMed1986

Central action of atrial natriuretic polypeptide on blood pressure in conscious rats.

The effect of intracerebroventricular administration of atrial natriuretic polypeptide on blood pressure was studied in conscious, unrestrained rats. The intracerebroventricular injection of alpha-human atrial natriuretic polypeptide did not promote any significant change in basal blood pressure, whereas it attenuated central angiotensin II-induced pressor response in a dose-dependent manner. The plasma atrial natriuretic polypeptide level did not change after the central administration of alpha-human atrial natriuretic polypeptide. These data implicate atrial natriuretic polypeptide as a factor in blood pressure regulation in the central nervous system.

Angiotensin II↗
PubMed1986

Neural activities in the monkey basal ganglia related to attention, memory and anticipation.

Discharges of single neurons were recorded in the caudate nucleus of an awake monkey. The monkey was trained to perform a series of behavioral tasks which required him to fixate on a spot of light on a screen and if the spot jumped to another location to make a saccade to refixate it. A significant portion of the neurons in the head and body of the caudate nucleus showed increases in their activities in relation to the behavioral tasks. While some neurons responded to the visual stimulus (light spot), others showed activities preceding a saccade. Another group of neurons showed activities not directly related to such sensory or motor events but presumably related to monkey's cognitive states. Even the visual or saccade-related activities were highly dependent on the behavioral context in which a given visual stimulus was presented or a given saccade was elicited. This report presents typical examples of caudate neural activities related to selective attention, short-term memory and anticipation of future events, and explains how such complex signals in the caudate are converted to oculomotor outputs through a major efferent pathway of the basal ganglia, namely caudate--substantia nigra pars reticulate--superior colliculus.

Animals↗
PubMed1986

Polysomnography--functional topographical examination of the basal ganglia.

Polysomnographical examinations were performed on two cases with unilateral lesion in the basal ganglia. One (case 1) was a 10-year-old girl with tuberous sclerosis with subependymal nodules on the left thalamostriatal sulcus and rotatory seizures, and pharmacologically the existence of a postsynaptic supersensitivity of the dopaminergic (DA) neurons, was suggested. The other (case 2) was an 8-year-old boy with infarction of the left putamen. Two types of body movements (BMs); gross movements (GM) and twitch movements (TM), were evaluated. The mode of occurrence of these BMs against each sleep stage, the pattern of BMs, and the ratio of the number of TM in the mentalis muscle in stage REM against the number of rapid eye movements (REMs) (ment TM REM/REMs) were estimated. The modulation of these parameters by L-Dopa and pimozide was studied. The pattern of GM reflected the DA activity of the side of the lesion. TM of the contralateral side reflected the pathophysiology of the lesion. TM of the ipsilateral extremities of case 1 showed the pattern of DA hyperactivity, which were reduced by small doses of L-Dopa. In case 2, TM of the ipsilateral extremities showed a normal pattern and rate, which increased markedly after L-Dopa. The TM of the sternocleidomastoideus revealed abnormal ipsilaterally in case 1 and contralaterally in case 2. The ment TM REM/REMs ratio reflected the real function of the DA neurons and did not reflect their hyperfunction due to postsynaptic supersensitivity. The numbers and direction of REMs might reflect the function of the basal ganglia, particularly of the DA neurons.

Basal Ganglia↗
PubMed1986

Centrally infused atrial natriuretic polypeptide attenuates exaggerated salt appetite in spontaneously hypertensive rats.

We have previously shown that atrial natriuretic polypeptide is present in the brain with the highest concentration in the hypothalamus and septum and that intracerebroventricular injection of atrial natriuretic polypeptide inhibits water drinking induced by centrally injected angiotensin II or 24-hour water deprivation in rats. To study further the role of brain atrial natriuretic polypeptide in the control of water and electrolyte balance, the effect of chronic intracerebroventricular infusion of atrial natriuretic polypeptide on salt appetite in spontaneously hypertensive rats and normotensive Wistar-Kyoto rats was examined with a free-choice, two-bottle preference test. The intracerebroventricular infusion of 100 ng/hour and 500 ng/hour of alpha-human atrial natriuretic polypeptide preferentially suppressed the intake of 0.30 M NaCl solution and attenuated the elevated preference for the hypertonic saline in spontaneously hypertensive rats while centrally infused alpha-human atrial natriuretic polypeptide had no significant effects on drinking behavior in Wistar-Kyoto rats. Blood pressure did not change significantly throughout the experiment in either rat strain. It is concluded that the exaggerated salt appetite in spontaneously hypertensive rats is blunted by centrally administered atrial natriuretic polypeptide. Such an effect of atrial natriuretic polypeptide along with its antidipsogenic effect suggests that brain atrial natriuretic polypeptide plays a role in water and electrolyte homeostasis and in blood pressure control.

Animals↗
PubMed1986

Increased tissue level of atrial natriuretic polypeptide in the hypothalamus and septum of spontaneously hypertensive rats.

To elucidate the pathophysiological role of atrial natriuretic polypeptide (ANP) in the brain in hypertension, the tissue concentrations and contents of alpha-rat ANP-like immunoreactivity (alpha-rANP-Ll) in the hypothalamus and septum of 4-week or 18-week-old spontaneously hypertensive rats (SHR) were studied using a radio-immunoassay (RIA) for alpha-rANP and compared with those of age-matched Wistar-Kyoto rats (WKY). The concentration and content of alpha-rANP-Ll in these regions of both 4-week and 18-week-old SHR were significantly higher that those of WKY (P less than 0.05). High performance gel permeation chromatography coupled with the RIA showed that the gel filtration profile of alpha-rANP-Ll in SHR was essentially identical to that of WKY. Since the hypothalamus and septum are known to be critical areas for water and electrolyte balance, and blood pressure control, these results suggest that ANP plays a pathophysiological role in these brain regions of SHR.

Animals↗
PubMed1986

Atrial natriuretic polypeptide in the brain: implication of central cardiovascular control.

Biologically active peptides isolated from peripheral organs often occur in the central nervous system, and vice versa. There is evidence that the effects of centrally active peptides are often, although not always, complementary to their peripheral actions. Atrial natriuretic polypeptide (ANP) is one of these biologically active peptides. Evidence presented here indicates that ANP is involved in the cardiovascular control as a neuropeptide in the central nervous system as well as a circulating hormone in the periphery.

Animals↗
PubMed1986

Leumorphin is a potent inhibitor of vasopressin secretion.

The effects of intracerebroventricular (i.c.v.) injection of leumorphin on the vasopressin secretion induced by angiotensin II or dehydration were studied in conscious unrestrained rats. The vasopressin secretion induced by angiotensin II (100 pmol) was significantly inhibited by the simultaneous injection of leumorphin (6 pmol-600 pmol) in a dose-dependent manner. In 72-hour water-deprived rats, the i.c.v. injection of leumorphin (60 pmol or 600 pmol) significantly suppressed the vasopressin secretion dose-dependently. These results suggest that leumorphin is involved in the regulation of the vasopressin secretion.

Angiotensin II↗
PubMed1986

Centrally administered leumorphin possesses potent depressor activity in conscious rats.

The effect of intracerebroventricular (i.c.v.) administration of leumorphin on basal blood pressure and angiotensin II (AII)-stimulated increase in blood pressure was examined in conscious unrestrained rats. The i.c.v. injection of leumorphin (0.06 and 0.6 nmol) elicited significant depressor effect. The i.c.v. administration of leumorphin with AII (0.1 nmol) significantly attenuated the AII-induced pressor response and, furthermore, lowered blood pressure below the basal level. These results suggest that leumorphin is involved in the central control of blood pressure.

Angiotensin II↗
PubMed1986

[Laboratory and clinical studies on cefmenoxime in respiratory tract infections].

Cefmenoxime (CMX, Bestcall) was administered by drip infusion to 65 patients with various respiratory infections and its effect was evaluated. The rate of effectiveness was 86.2% in all cases including 40 cases of acute pneumonia and 12 cases of chronic bronchitis. CMX was examined comparatively with other drugs for antibacterial activity on clinically isolated strains of 2 bacterial species, i.e. H. influenzae and B. catarrhalis, each of which has a high frequency of clinical isolation from infected respiratory organs. On H. influenzae CMX exerted the strongest antibacterial activity among test drugs (ampicillin, piperacillin cefoperazone, latamoxef) regardless of the production of beta-lactamase by the organism, while on B. catarrhalis it also exerted an antibacterial activity strong enough to control the proliferation of all strains at a dose level of 0.39 microgram/ml. Drip infusion of this drug (2 gram) brought about an average maximum blood concentration of 127.2 +/- 21.5 micrograms/ml and an average half-life in blood of 1.10 +/- 0.28 hours. However, different values were obtained for different individual cases because these subjects were patients of chronic respiratory infections each having some underlying disease or other. Side effects of the drug were observed as allergic symptoms such as pyrexia, eruption and the like, but only 5 cases without any serious cases. Increases in transaminase suggestive of abnormal clinical test results were also observed in 5 cases. However, numerical recoveries to the normal values were obtained in all of these 5 cases with the withdrawal of the drug.

Adolescent↗
PubMed1986

[Clinical studies of efficacy of piperacillin against complicated urinary tract infections].

Clinical efficacy of piperacillin against 74 cases with complicated urinary tract infection was examined. Piperacillin was administered at the dose of 4 g (2 g twice daily) through intravenous drip infusion. The overall clinical value was rated in "excellent", in 9 cases, "moderate" in 34 cases and "poor" in 31 cases with a total efficacy of 58.1%. In the analysis of clinical values based on background, its efficacy was statistically significantly lower in the patients at a higher age, those with complication of diabetes mellitus, and those with indwelling catheter. In operated cases compared to non-operated cases, it was suggested to be more effective for improving the disturbances in urinary flow as a result of the removal of the underlying conditions by the operation. As to bacteriological efficacy, 64 out of 95 strains (67.4%) isolated were eradicated following its administration. Microbes which appeared after its dosing belonged to 9 classes of 18 strains, of which 5 strains (27.8%) of Serratia were identified. Side effects were 2.5% (3/119), no serious cases appeared. Changes in laboratory examination results were elevated GOT (2.5%), GPT (1.7%), and ALP (0.8%) values, all being transient hanges.

Adult↗