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Biomedical subjects

S Morimoto

Publications and source records attributed to S Morimoto.

At least 613 records · Page 34Linked to original sources
PubMed1986

Effects of angiotensin II, adrenocorticotropin, and potassium on aldosterone production in adrenal zona glomerulosa cells from streptozotocin-induced diabetic rats.

Hyporeninemic hypoaldosteronism has been shown to occur in streptozotocin-induced chronic diabetic rats with normokalemia. To test the nature of the aldosterone deficiency, we investigated the responses of aldosterone production to angiotensin II (AII), ACTH, and potassium in adrenal zona glomerulosa cells from diabetic rats at 6 weeks after an injection of streptozotocin compared with those in the cells from control rats. In diabetic rats, plasma glucose was high and plasma immunoreactive insulin was low. Diabetic rats also had low levels of PRA and plasma AII, low levels of plasma aldosterone, and normal levels of plasma corticosterone and plasma potassium. The zona glomerulosa width was narrower in diabetic rats than in control rats. Basal aldosterone production, when corrected to an uniform number of cells per group, was similar in the cells from control and diabetic rats. Cells from diabetic rats showed a less sensitive and lower response of aldosterone production to AII, increases in the threshold and the ED50, and a decrease in the maximal AII-stimulated aldosterone level. ACTH, however, caused a similar effect on aldosterone production in the cells from control and diabetic rats. Cells from diabetic rats exhibited a less sensitive response of aldosterone production to potassium and a tendency to be low in the maximal potassium-stimulated aldosterone level, presumably attributable to the impairment of adrenal zona glomerulosa cells to AII. We conclude that the hypoaldosteronism observed in our diabetic rats may be secondary to the deficiency of AII.

Adrenal Glands↗
PubMed1986

Hormonal regulation of (Ca2+ + Mg2+)ATPase activity in canine renal basolateral membrane.

High affinity (Ca2+ + Mg2+)ATPase activity was demonstrated in proximal tubule basolateral membranes (BLM) obtained from canine kidney. The Km of the enzyme for free Ca2+ was 0.12 +/- 0.02 microM, and at 3 microM free Ca2+, the enzyme reached its maximal velocity. To evaluate hormonal regulation of this enzyme, we studied the in vitro effects of several polypeptide hormones on enzyme activity. We measured the effects of insulin and human (h) PTH-(1-34) and their inactive analogs desoctapeptide insulin, bovine (b) PTH-(3-34), and oxidized hPTH-(1-34); insulin-like growth factors (IGFs) I and II; calcitonin; and the common cellular mediator for PTH and calcitonin, cAMP. At 0.1 microM free Ca2+, insulin (25-100 microU/ml) increased (Ca2+ + Mg2+)ATPase activity in a dose-dependent manner by 35-52% (P less than 0.01) and by 8-13% (P less than 0.05 to P less than 0.01) at a 3-microM free Ca2+ concentration; hPTH-(1-34) PTH (10(-9)-10(-7) M) increased the enzyme activity at a free Ca2+ concentration of 0.1 microM by 13-25% (P less than 0.05 to P less than 0.01). IGF-I increased (Ca2+ + Mg2+)ATPase activity by 40% (P less than 0.05) at 0.1 microM free Ca2+ at high peptide concentrations (10 ng/ml). No effect was obtained at 2 ng/ml IGF-I. cAMP (10(-7)-10(-4) M) stimulated enzyme activity by 18-27% (P less than 0.05 to P less than 0.02) at 0.1 microM Ca2+ and by 8-12% (P less than 0.05 to P less than 0.01) at 3 microM Ca2+. The effects of insulin and cAMP on (Ca2+ + Mg2+)ATPase activity were additive. No effect on the enzyme activity was obtained by the inactive analogs desoctapeptide insulin, bPTH-(3-34), and oxidized hPTH-(1-34), or by calcitonin or IGF-II. The data suggest that insulin and PTH have a specific stimulatory effect on (Ca2+ + Mg2+)ATPase activity in canine kidney proximal tubular BLM. While the insulin action is independent of cAMP, a role of cAMP in the regulatory effect of PTH on this enzyme cannot be ruled out. The direct stimulatory effect of insulin and PTH on (Ca2+ + Mg2+)ATPase in canine kidney proximal tubular BLM suggests that these hormones mediate their cellular effects in part by changes in cellular calcium homeostasis.

Animals↗
PubMed1986

Effects of pinacidil on renal hemodynamics and function in anesthetized dogs.

We studied the effects of pinacidil on renal hemodynamics and function in anesthetized dogs. An intravenous injection of pinacidil, at a dose of 0.25 mg/kg, resulted in a rapid and marked reduction of the mean systemic blood pressure (MSBP) accompanied by a significant increase in renal blood flow (RBF). There were no significant changes in glomerular filtration rate (GFR), urine flow (UF) and urinary excretion of electrolytes (UEE). When pinacidil was administered at a dose of 0.5 mg/kg, the hypotensive effect was more potent. RBF did not change, but GFR, UF and UEE significantly decreased. These antidiuretic effects were not influenced by renal denervation. Hydralazine, at doses of 0.5 and 2.0 mg/kg, caused a significant and sustained reduction of MSBP, but the effects were much less potent than those seen with pinacidil. A sustained increase in RBF was observed after hydralazine at both doses. The lower dose elicited increases in UF and UEE, although the GFR remained unchanged. The higher dose of hydralazine caused a reduction of GFR, accompanied by decreases in UF and UEE. These antidiuretic effects were abolished by renal denervation. Intravenous injection of pinacidil or hydralazine produced a significant increase in the renin secretion rate. Intrarenal arterial infusion of pinacidil (2.0 micrograms/kg/min) produced a more marked diuretic effect than hydralazine (20 micrograms/kg/min). These findings indicated that the hypotensive activity of pinacidil is more potent than that of hydralazine, and suggested that the antidiuretic action of i.v. pinacidil (0.5 mg/kg) is due to a reduction of renal perfusion pressure. Furthermore, this drug may exert an additional action in the kidney to cause diuresis.

Animals↗
PubMed1986

Effects of labetalol on renin release from rat kidney cortical slices.

Effects of labetalol, a combined alpha- and beta-adrenoceptor blocking agent, on the changes in renin release in response to isoproterenol or norepinephrine were examined in comparison with those of propranolol and prazosin, using rat kidney cortical slices. Isoproterenol (10(-9) to 10(-5) M) produced a dose-related increasing effect on renin release from the slices, although the increased release was markedly attenuated by the higher dose (10(-4) M). On the other hand, norepinephrine, at relatively higher concentrations (over 10(-6) M), caused a significant decreasing action on the release. Labetalol alone (10(-9) to 10(-4) M) had no effect on basal renin release. However, the agent exerted a concentration-dependent blocking action on the renin response to 10(-6) M isoproterenol. Similar results were observed with propranolol. The decreased response of renin release to 10(-5) M norepinephrine was significantly inhibited by labetalol over 10(-6) M. Labetalol, at a concentration of 10(-5) M, abolished the decreased release by 10(-5) M norepinephrine. On the other hand, the decreasing effect of 10(-5) M norepinephrine was substantially reversed rather than abolished by prazosin over 10(-7) M. These results indicate that labetalol inhibited the response of renin in rat kidney cortical slices, by beta- and alpha 1-adrenoceptor antagonistic action, respectively.

Animals↗
PubMed1986

Age-associated myocardial changes in various heart diseases. A clinicopathologic analysis in biopsied and autopsied myocardium.

Age-associated changes in histopathologic and ultrastructural aspects of cardiac myocytes were systematically compared with clinical problems. The study material consisted of 1,515 endomyocardial biopsies; 150 normal and 50 diseased cardiac myocytes from pediatric autopsy specimens; 34 intraoperative endomyocardial biopsy specimens from the left ventricle and 28 surgical biopsy specimens from the right or left atrium. The following results were obtained: The myocytes developed to adult size by the age of 15 years. Thereafter, the size did not change up to the age of 59. Short-term hemodynamic overloading to the ventricle caused reactive hyperfunction and hypertrophy of myocytes. Stable hypertrophy resulted in long-term overloading. In cardiomyopathy, compensated or stable hypertrophy occurred, but progression to decompensated or gradual exhaustion and progressive cardiosclerosis (Meerson) took place. Progress of endocardial thickening was often observed during the course of the disease. In the right and left atrial myocardium, extremely advanced pathology was observed and changes were related to the duration of the disease rather than to the severity of the hemodynamics.

Aging↗
PubMed1986

Ventricular volume of single ventricle with or without palliation and after corrective surgery--concept of septation procedure.

Ventricular volume measurements of single ventricle were carried out in 20 patients with or without palliation and in 2 after total correction. In the former 20 patients, 6 had a single left ventricle and 14 a single right ventricle, anatomically. Two having total correction were associated with undivided ventricle. In the 20 patients with or without palliation, ventricular end-diastolic volume ranged from 64 to 206 (115 +/- 42) percent of the sum of the normal left and right ventricular volumes. Ejection fraction of single ventricle ranged from 0.40 to 0.64 (0.55 +/- 0.06). There was no significant difference in ventricular volume and ejection fraction between patients with a single left and right ventricle. There was high correlation of ventricular volume with pulmonary to systemic blood flow ratio (r = 0.66, p less than 0.005). This indicates that systemic-to-pulmonary shunt should increase ventricular volume of single ventricle. In two patients after total correction, total ventricular volume was 136 and 166% of the sum of the normal left and right ventricular volumes. Total ejection fraction was 0.55 and 0.33 in the first and second patient, respectively. The prosthetic ventricular septum bulged toward the right ventricle during systole and this shift made the left ventricular volume increase and ejection fraction decrease. Right-to-left ventricular volume ratio at end-diastole was 0.74 and 0.67 in the first and second patient, respectively. These results suggest that 1) larger ventricular volume than the sum of the normal left and right ventricular volumes would be required for septation of single ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart Septum↗
PubMed1986

[Effects of ipriflavone (TC-80, an anti-osteoporotic drug) on acute and chronic pain].

The effects of TC-80 on acute and chronic pain in rats and mice were examined. Single oral administration of TC-80 at 50-300 mg/kg was not analgesic in the phenylquinone writhing, acetic acid writhing, and hot plate tests in mice or the tail flick test in rats. Three-weeks administration of TC-80 in a dose of 100 mg/kg/day, p.o., to rats had no analgesic action in the acetic acid writhing and tail flick tests. When TC-80 was given orally in a dose of 100 mg/kg/day for 3 weeks to rats with adjuvant arthritic chronic pain, analgesic effects were observed 2 weeks after the start of administration in males and in ovariectomized estrone-supplemented females; the effect seen in the females was statistically significant. Changes in the bones of the hind paws were examined radiologically, and synovitis, periosteal new bone formation and bone destruction were examined histopathologically in the females. These variables were improved by treatment with TC-80 for 3 weeks. It is concluded that TC-80 has no analgesic effect, but may inhibit chronic pain by anti-osteoporotic action on bone disease.

Administration, Oral↗
PubMed1986

Age and sex influences on urine calcitonin-like immunoreactivity in normal subjects.

Calcitonin-like immunoreactivity levels were determined in urine specimens in 585 normal subjects of various ages. Urine calcitonin-like immunoreactivity (uCTi) was measured by the midportion-specific radioimmunoassay after extraction of urine by gel chromatography on a 0.8 X 20 cm column of Bio Gel P-2. In 197 males and 169 females below 20 years old, significant negative correlations between the age and uCTi were observed (male: r = -0.684, female: r = -0.690). In 75 males and 80 females above 41 years, however, no significant correlation was observed between age and uCTi. The high level of uCTi in children could be explained by high levels of circulating calcitonin, associated with rapid bone growth; however the uCTi level in the elderly may not reflect the physiological significance of calcitonin for them because of a suspected age-related decrease in renal clearance of uCTi in the elderly.

Adolescent↗
PubMed1986

Effect of angiotensin II on aldosterone and its precursor steroid production in adrenal zona glomerulosa cells from heparin-treated rats.

To assess the nature of the heparin-induced aldosterone deficiency, we investigated the stimulatory effect of angiotensin II (AII) on aldosterone and its precursor steroids in adrenal zona glomerulosa cells from heparin-treated rats compared with those in the cells from vehicle-treated rats. Heparin-treated rats had low plasma aldosterone levels, high plasma renin activity and plasma AII levels, and normal plasma corticosterone level 6 weeks after the treatment (1500 IU/kg, twice daily). Basal aldosterone production, when corrected to a uniform number of cells per group, was similar in the cells from heparin- and vehicle-treated rats. The cells from heparin-treated rats had a less sensitive and lower response of aldosterone production to AII; an increase by 4 orders of magnitude in the threshold dose for AII and a decrease in the maximum AII-stimulated level. The maximum AII-stimulated levels, but not the basal levels, of pregnenolone, corticosterone and 18-OHB production were low in the cells from heparin-treated rats. ACTH caused a similar stimulatory effect on aldosterone production in the cells from heparin- and vehicle-treated rats. The cells from heparin-treated rats had a less sensitive and lower response of aldosterone production to potassium; an increase by one order of magnitude in the threshold dose for potassium and a decrease in the maximum potassium-stimulated level, presumably because of the glomerulosa hyporesponsiveness to AII. These results suggest that our heparin-treated rats have selective impairment of adrenal zona glomerulosa cells, involving the specific receptors and the aldosterone biosynthesis, to AII.

18-Hydroxycorticosterone↗
PubMed1986

Effect of length change in muscle fibers on conduction velocity in human motor units.

Length and conduction velocity were determined in muscle fibers belonging to the single motor unit (right m. vastus medialis) in the living human body. A new method was developed for measuring the length of fibers, i.e., the muscle length was defined to be the distance between the starting point of excitation (motor end-plate) and the distal end of muscle fibers belonging to the particular motor unit. Both points were decided by analyzing the shape of the spike potentials of the motor unit recorded by surface electrodes. The length increased by about 70% (ranging from 48% to 97%) when changing the knee angle from fully extended to the fully flexed position, whereas the conduction velocity decreased by about 26% (ranging from 17 to 36%). It can be considered that the decrease of the conduction velocity when increasing the length of the muscle fibers was mainly due to the decrease in fiber diameter.

Adult↗
PubMed1986

Functioning parathyroid cyst extending from neck to anterior mediastinum. Diagnosis by sonography and computed tomography.

A parathyroid cyst was evaluated by sonography and computed tomography (CT) in a patient with hyperparathyroidism. Sonography demonstrated a cystic lesion near the left lower pole of the thyroid, extending into the anterior mediastinum. On CT, the parathyroid cyst had a slightly high attenuation (30 H), with a smooth wall demonstrated after intravenous administration of contrast material. Fine-needle aspiration biopsy of the cyst showed elevated parathyroid hormone (PTH) level. The lesion probably represents cystic degeneration of an adenoma.

Aged↗
PubMed1986

Schwannoma of the trachea.

We recently encountered a tracheal schwannoma presenting as a polypoid mass. Computed tomography (CT) was very effective in evaluation of the size, shape and site of this rare tumour. Furthermore, CT images in the prone position made it easy to exclude tumour extension into the mediastinum.

Humans↗