Search PubMed⌕ Search

Biomedical subjects

J Iwamoto

Publications and source records attributed to J Iwamoto.

At least 37 records · Page 2Linked to original sources
PubMed2001

Flow-mediated release of nitric oxide in isolated, perfused rabbit lungs.

The effects of changing perfusate flow on lung nitric oxide (NO) production and pulmonary arterial pressure (Ppa) were tested during normoxia and hypoxia and after N(G)-monomethyl-L-arginine (L-NMMA) treatment during normoxia in both blood- and buffer-perfused rabbit lungs. Exhaled NO (eNO) was unaltered by changing perfusate flow in blood-perfused lungs. In buffer-perfused lungs, bolus injections of ACh into the pulmonary artery evoked a transient increase in eNO from 67 +/- 3 (SE) to 83 +/- 7 parts/billion with decrease in Ppa, whereas perfusate NO metabolites (pNOx) remained unchanged. Stepwise increments in flow from 25 to 150 ml/min caused corresponding stepwise elevations in eNO production (46 +/- 2 to 73 +/- 3 nl/min) without changes in pNOx during normoxia. Despite a reduction in the baseline level of eNO, flow-dependent increases in eNO were still observed during hypoxia. L-NMMA caused declines in both eNO and pNOx with a rise in Ppa. Pulmonary vascular conductance progressively increased with increasing flow during normoxia and hypoxia. However, L-NMMA blocked the flow-dependent increase in conductance over the range of 50-150 ml/min of flow. In the more physiological conditions of blood perfusion, eNO does not reflect endothelial NO production. However, from the buffer perfusion study, we suggest that endothelial NO production secondary to increasing flow, may contribute to capillary recruitment and/or shear stress-induced vasodilation.

Acetylcholine↗
PubMed2001

Role of airway nitric oxide on the regulation of pulmonary circulation by carbon dioxide.

The effects of hypercapnia (CO(2)) confined to either the alveolar space or the intravascular perfusate on exhaled nitric oxide (NO), perfusate NO metabolites (NOx), and pulmonary arterial pressure (Ppa) were examined during normoxia and progressive 20-min hypoxia in isolated blood- and buffer-perfused rabbit lungs. In blood-perfused lungs, when alveolar CO(2) concentration was increased from 0 to 12%, exhaled NO decreased, whereas Ppa increased. Increments of intravascular CO(2) levels increased Ppa without changes in exhaled NO. In buffer-perfused lungs, alveolar CO(2) increased Ppa with reductions in both exhaled NO from 93.8 to 61.7 (SE) nl/min (P < 0.01) and perfusate NOx from 4.8 to 1.8 nmol/min (P < 0.01). In contrast, intravascular CO(2) did not affect either exhaled NO or Ppa despite a tendency for perfusate NOx to decline. Progressive hypoxia elevated Ppa by 28% from baseline with a reduction in exhaled NO during normocapnia. Alveolar hypercapnia enhanced hypoxic Ppa response up to 50% with a further decline in exhaled NO. Hypercapnia did not alter the apparent K(m) for O(2), whereas it significantly decreased the V(max) from 66.7 to 55.6 nl/min. These results suggest that alveolar CO(2) inhibits epithelial NO synthase activity noncompetitively and that the suppressed NO production by hypercapnia augments hypoxic pulmonary vasoconstriction, resulting in improved ventilation-perfusion matching.

Animals↗
PubMed2001

Effect of circular motion exercise on bone modeling and bone mass in young rats: an animal model of isometric exercise.

The aims of the study are to develop a non-invasive animal model of circular motion exercise and to evaluate the effect of this type of exercise on bone turnover in young rats. The circular motion exercise simulates isometric exercise using an orbital shaker that oscillates at a frequency of 50 Hz and is capable of speeds from 0-400 rpm. A cage is fixed on top of the shaker and the animals are placed inside. When the shaker is turned on, the oscillatory movement should encourage the animals to hold on to the cage and use various muscle forces to stabilize themselves. Rats at 8 weeks of age were trained on the shaker for 6 weeks and static and dynamic histomorphometric analyses were performed for the proximal tibial metaphysis and the tibial shaft. The exercise resulted in no significant effect on animal body weight, gastrocnemius muscle weight and femoral weight. Although the bone formation rate of cancellous and cortical periosteum was increased by the exercise, trabecular bone volume was decreased. The exercise increased periosteal and marrow perimeters and the cross-sectional diameter of cortical bone from medial to lateral without a significant increase in the cortical bone area. These results suggest that circular motion exercise under force without movement or additional weight loading will cause bone-modeling drift with an increase in bone turnover to reconstruct bone shape in adaptation to the demand in strength. Since there is no additional weight loading during circular motion exercise, the net mass of bone is not increased. The bone mass lost in trabecular bone could possibly be due to a re-distribution of mineral to the cortical bone.

Journal Article↗
PubMed2000

Age-related changes in cortical bone in men: metacarpal bone mass measurement study.

Metacarpal cortical bone mass was measured in 507 healthy Japanese men aged 40-95 years, using a microdensitometer to determine age-related changes in cortical bone in these middle-aged and elderly men. Total bone mass showed a significant negative correlation with age (r = -0.281; P < 0.0001). While bone width showed no significant correlation with age, bone marrow width showed a significant positive correlation (r = 0.210; P < 0.0001), and cortical bone width and cortical bone density showed a significant negative correlation with age (r = -0.265; P < 0.0001; r = -0.268; P < 0.0001, respectively). On the other hand, cortical bone width and cortical bone density showed a significant positive correlation with total bone mass (r = 0.814; P < 0.0001; r = 0.474, P < 0.0001, respectively). These findings suggest that cortical bone mass decreases significantly with aging in middle-aged and elderly men, perhaps as a result of two factors - decreased cortical bone width, ie, cortical bone thinning due to bone loss at the endosteal side of the cortex, and decreased cortical bone density due to progression of intracortical porosity. Cortical bone thinning may influence age-related cortical bone loss more than decreasing cortical bone density.

Adult↗
PubMed2000

Effect of combined administration of vitamin D3 and vitamin K2 on bone mineral density of the lumbar spine in postmenopausal women with osteoporosis.

The effect of the combined administration of vitamin D3 and vitamin K2 on bone mineral density (BMD) of the lumbar spine was examined in postmenopausal women with osteoporosis. Ninety-two osteoporotic women who were more than 5 years after menopause, aged 55-81 years, were randomly divided into four administration groups: vitamin D3 (1alpha hydroxyvitamin D3, 0.75 microg/day) (D group; n = 29), vitamin K2 (menatetrenone, 45 mg/day) (K group; n = 22), vitamin D3 plus vitamin K2 (DK group, n = 21), and calcium (calcium lactate, 2 g/day) (C group; n = 20). BMD of the lumbar spine (L2-L4) was measured by dual energy X-ray absorptiometry at 0, 1, and 2 years after the treatment started. There were no significant differences in age, body mass index, years since menopause, and initial BMD among the four groups. One-way analysis of variance (ANOVA) with repeated measurements showed a significant decrease in BMD in the C group (P < 0.001). Two-way ANOVA with repeated measurements showed a significant increase in BMD in the D and K groups compared with that in the C group (P < 0.05 and P < 0.001, respectively), and a significant increase in BMD in the DK group compared with that in the C, D, and K groups (P < 0.0001, P < 0.05 and P < 0.01, respectively). These findings indicate that combined administration of vitamin D3 and vitamin K2, compared with calcium administration, appears to be useful in increasing the BMD of the lumbar spine in postmenopausal women with osteoporosis.

Aged↗
PubMed2000

The cytoprotective role of lipopolysaccharide-induced nitric oxide against liver damage during early phase of endotoxemia in rats.

Lipopolysaccharide (LPS)-induced endotoxemia produces nitric oxide (NO); however, the role of the NO during endotoxemia is still controversial. The aim of this study was to investigate a role of LPS-induced NO during the early phase of endotoxemia. Wistar rats were intraperitoneally injected with saline or LPS at various doses (0.001, 0.01, or 5 mg/kg), and intra-abdominal NO concentration was determined by chemiluminescence before and after LPS administration at indicated times (1, 2, 6, 10, and 18 h). Serum aspartate aminotransferase and alanine aminotransferase levels were determined and histological examination was performed 10 h after LPS administration to assess liver damage. N(G)-nitro-L-arginine-methyl ester (L-NAME), a nonselective inhibitor of NO synthase, was used to investigate the possible roles of NO during LPS-induced endotoxemia. The intra-abdominal NO concentration was elevated within 2 h and reached a maximal level at 10 h after low doses of LPS injection (0.001 and 0.01 mg/kg) while liver damage was not observed. After high-dose LPS (5 mg/kg) administration, liver damage was observed and intra-abdominal NO was elevated continuously until 18 h. A time course study revealed very similar patterns of intra-abdominal NO increase after the three different dose of LPS at each times points during the first 10 h. Pretreatment of L-NAME inhibited the intra-abdominal NO release and aggravated the liver damage caused by low doses (0.001 and 0.01 mg/kg) of LPS as well as high dose (5 mg/kg) of LPS. Therefore, NO, released during the first 10 h after LPS injection, may play a cytoprotective role in the liver.

Alanine Transaminase↗
PubMed2000

Reduced nasal nitric oxide in diffuse panbronchiolitis.

Diffuse panbronchiolitis (DPB) is a pulmonary disease of unknown origin with inflammation in the respiratory bronchioles, bronchiectasis, and recurrent sinusitis. Patients with DPB suffer from chronic airway infections resulting from mucociliary dysfunction. Whereas a high concentration of nasal nitric oxide (NO) has been documented in healthy subjects, only two diseases are known to reduce nasal NO: primary ciliary dyskinesia syndrome and cystic fibrosis. We hypothesized that patients with DPB have abnormal levels of nasal NO. To test our hypothesis, we measured NO with the chemiluminescence technique. Air was sampled directly from the nose in 15 healthy subjects and eight patients with DPB. Nasal NO was 88% lower in DPB patients than in the age-matched control subjects (69 +/- 70 versus 556 +/- 87 nl/min; p < 0.001). Treatment with erythromycin for 2 wk did not alter the nasal NO in four control subjects. DPB is the third pulmonary disease in which nasal NO is low. The reduced nasal NO may well be involved in the pathogenesis of DPB, and NO measurements may serve as a noninvasive test in the diagnosis of DPB.

Adult↗
PubMed2000

Effect of deconditioning on cortical and cancellous bone growth in the exercise trained young rats.

Exercise enhances bone growth and increases peak bone mass. The aim of this study was to determine whether or not 4 weeks of deconditioning after 8 weeks of exercise in growing rats would result in a decrease in bone gain or reverse the benefits of exercise. Fifty 4-week-old female Sprague-Dawley rats were randomized by a stratified weight method into 5 groups with 10 rats in each group: 8 weeks exercise (8EX), 8 weeks sedentary control (8S), 12 weeks exercise (12EX), 8 weeks exercise followed by 4 weeks sedentary (8EX4S), and 12 weeks sedentary control (12S). The exercise consisted of running on a treadmill with a 5 degrees slope at 24 m/minute for 1 h/day and 5 days/week. After each period of exercise, cancellous and cortical bone histomorphometry were performed on double fluorescent labeled 5-microm-thick sections of the proximal tibia and 40-microm-thick sections of the tibial shaft, respectively. Eight and 12 weeks of exercise resulted in a significant increase in the body weight and gastrocnemius muscle weight by two-way analysis of variance (ANOVA). The femoral wet weight (mg; mean +/- SD; 8EX, 781 +/- 45.1 vs. 8S, 713 +/- 40.5; p < 0.05; 12EX, 892 +/- 41.6 vs. 12S, 807 +/- 19.8; p < 0.05) was significantly higher in the exercise group than that in the respective control groups. The femoral wet weight and bone volume (BV) of the 8EX4S group (818 +/- 46.2 mg and 531 +/- 31.2 microl, respectively) were significantly lower than those of the 12EX group (p < 0.05) and did not differ significantly from those of the 12S groups. The cancellous BV was significantly higher in the 8EX and 12EX groups than that in the respective sedentary groups (p < 0.05). The cortical bone area of the tibial shaft was also significantly higher in the 12EX than that in the 12S group (p < 0.05). The increase in the cancellous BV or cortical bone area was caused by an increase in the mineral apposition rate (MAR), without a significant effect in the labeled perimeter. The bone formation rate (BFR; microm3/microm2 per day) in the cancellous bone (12EX, 27.9 +/- 7.74 vs. 12S, 15.4 +/- 4.56; p < 0.05) or periosteal surface (12EX, 127.6 +/- 27.7 vs. 12S, 79.5 +/- 18.6; p < 0.05) was significantly higher in the exercised groups than that in the respective control group (p < 0.05). Again, deconditioning resulted in a decrease in the cancellous BFR, BV, periosteal BFR, and cortical bone area to levels not significantly different from the 12S group. In conclusion, our findings showed that exercised growing rats, when deconditioned, lost the benefits gained through exercise and their bone parameters were reduced to levels not different from the sedentary control. Thus, continued exercise is required to maintain high bone mass.

Animals↗
PubMed1999

Differential effect of treadmill exercise on three cancellous bone sites in the young growing rat.

The aim of the present study was to examine cancellous bone changes induced by exercise on three different skeletal sites, the lumbar vertebra, the proximal, and the distal tibia, in the young growing rat. Forty 4-week-old female Sprague-Dawley rats were randomized into 4 groups of 10 animals each; 8 weeks exercise (8EX), 8 weeks sedentary control (8CON), 12 weeks exercise (12EX), and 12 weeks sedentary control (12CON). The exercise regimen consisted of treadmill running at 24 m/min 1 hr per day 5 days a week. After each period of exercise, the proximal and distal tibial metaphyses (PTM and DTM, respectively) and the fifth lumbar (L5) vertebral body were processed for histomorphometry of the cancellous bone (secondary spongiosa) and cortical periosteum. Eight and twelve weeks of exercise significantly increased the mineral apposition rate and bone formation rate in the PTM and DTM, and 12 weeks of exercise significantly increased the labeled perimeter in the DTM, compared with the age-matched controls. Eight and twelve weeks of exercise significantly increased cancellous bone volume in the PTM (mean +/- standard deviation, 8EX; 19.1 +/- 2.9% vs 8CON; 14.3 +/- 3.1%, P < 0.05 and 12EX; 18.8 +/- 3.5% vs 12CON; 15.2 +/- 3.3%, P < 0.05), and 12 weeks exercise significantly increased cancellous bone volume in the DTM, compared with age-matched control (12EX; 32.5 +/- 7.7%, 12CON; 22.2 +/- 4.8%, P < 0.05). The increase in cancellous bone volume by 12 weeks exercise was higher in the DTM than that in the PTM (43.4% and 24.0%, respectively). On the other hand, the exercise did not significantly affect cancellous bone volume and bone formation in the L5 vertebral body, although the cortical periosteal bone formation rate and the L5 vertebral bone mass were increased. These findings suggest that cancellous bone adaptation to treadmill exercise is site specific, and the effect may be influenced by factors such as mechanical loading and metaphyseal bone architecture in the young growing rat.

Adaptation, Physiological↗
PubMed1999

Regulation of pulmonary circulation by alveolar oxygen tension via airway nitric oxide.

The effects of airway (AH) and vascular hypoxia (VH) on the production of nitric oxide (NO; VNO) were tested in isolated buffer-perfused (BFL) and blood-perfused rabbit lungs (BLL). To produce AH and/or VH, the lung was ventilated with 1% O(2) gas, and/or the perfusate was deoxygenated by a membrane oxygenator located on the inlet limb to the pulmonary artery. We measured exhaled NO (VNO), accumulation of perfusate NOx, and pulmonary arterial pressure (Ppa) during AH (inspired O(2) fraction = 0.01) and/or VH (venous PO(2) = 26 Torr). In BFL, a pure AH without VH caused decreases in VNO and NOx accumulation with a rise in Ppa. However, neither VNO, NOx accumulation, nor Ppa changed during VH. Similarly, in BLL, only AH reduced VNO, although NOx accumulation was not measurable because of Hb. When alveolar PO(2) was gradually reduced from 152 to 0 Torr for 20 min, AH reduced VNO curvilinearly from 73.9 +/- 8 to 25.6 +/- 8 nl/min in BFL and from 26.0 +/- 2 to 5. 2 +/- 1 nl/min in BLL. This plot was analogous to that of a substrate-velocity curve for an enzyme obeying Michaelis-Menten kinetics. The apparent Michaelis-Menten constant for O(2) was calculated to be 23.2 microM for BLL and 24.1 microM for BFL. These results indicate that the VNO in the airway epithelia is dependent on the level of inspired O(2) fraction, leading to the tentative conclusion that epithelial NO synthase is O(2) sensitive over the physiological range of alveolar PO(2) and controls pulmonary circulation.

Animals↗
PubMed1998

Nitric oxide release from the liver surface to the intraabdominal cavity during acute endotoxemia in rats.

Nitric oxide (NO) is produced by the liver during lipopolysaccharide (LPS)-induced endotoxemia. The aim of this study was to examine whether NO, which is produced in the liver, is released from the liver surface to the intraabdominal cavity during endotoxemia. NO was quantitatively determined by chemiluminescence and a newly developed gas purge technique was used to directly measure NO released from the liver surface and the intraabdominal cavity of rats before and after LPS (0.1 mg/kg, intraperitoneally) or saline administration. The expression of inducible NO synthase (iNOS) mRNA in the liver was detected by Northern blot analysis. NO levels from both the liver surface and in the intraabdominal cavity were elevated at 2 h after LPS injection and peaked at 10 h and both the time course of NO level were well correlated with each other. Both NO levels were below the detectable range before LPS and after saline administration. Inducible NOS mRNA in the liver exhibited a sharp increase to a maximum level at 4 h after LPS injection. The present study indicates that the hepatic NO, which might have been produced by iNOS in the liver, is released from the liver surface to the intraabdominal cavity during endotoxemia.

Acute Disease↗
PubMed1998

Age-related changes in cortical bone in women: metacarpal bone mass measurement study.

The mechanism of age-related cortical bone loss was investigated in 229 Japanese women, 41-94 years of age, by metacarpal bone mass measurement. While no significant correlation was found between bone width and age, a significant increase in bone marrow width, and significant decreases in cortical bone density and total bone mass were observed in association with aging (P < 0.0001). There was a significant negative correlation between total bone mass and bone marrow width (r = -0.239; P < 0.0005), and significant positive correlations between both total bone mass and cortical bone density (r = 0.539; P < 0.0001) and cortical bone width (r = 0.839; P < 0.0001). The findings suggested that age-related cortical bone loss in middle-aged and elderly women resulted from two different factors; a decrease in cortical bone density caused by progression of intracortical porosity, and a decrease in cortical bone width as a result of bone loss on the endosteal surface. The latter had a greater influence on an age-related cortical bone loss than the former.

Absorptiometry, Photon↗
PubMed1998

Effect of exercise on tibial and lumbar vertebral bone mass in mature osteopenic rats: bone histomorphometry study.

The effect of moderate running exercise on tibial and lumbar vertebral bone mass was examined in mature osteopenic rats by bone histomorphometry. Ten 37-week-old female Wistar rats, with bone loss resulting from being fed a relatively low-calcium diet for 14 weeks after ovariectomy at the age of 23 weeks, were randomly divided into two groups of five animals each; control and exercise groups. The exercise consisted of treadmill running at 12 m/min for 1 h per day on 5 days per week for 12 weeks. During the exercise period, all animals were fed a standard calcium diet. After 12 weeks of exercise, bone histomorphometry was evaluated for cancellous bone (secondary spongiosa) of the proximal tibia and the fourth lumbar vertebra and for cortical bone of the tibial shaft. The findings suggested that in the mature osteopenic rat, there was a beneficial effect of moderate running exercise with adequate calcium intake on bone mass only in a weight-bearing long bone, the tibia. The mechanism for increased bone mass appeared to be both decreased bone resorption and increased bone formation in cancellous bone and increased bone formation in cortical bone.

Analysis of Variance↗
PubMed1998

Inhaled nitric oxide therapy via nasopharyngeal tube in an infant with end-stage pulmonary hypertension.

The delivery of nitric oxide (NO) via a nasopharyngeal tube is an alternative to endotracheal intubation. A male infant with end-stage pulmonary hypertension (PH) due to a severe hypoplastic lung developed a PH crisis on day 145 and received NO inhalation via a nasopharyngeal tube. Clinical improvement was maintained for 7 days with 18-22 ppm NO inhalation. The patient remained in close physical contact with his parents without the use of sedation. Blood methemoglobin levels remained below 1%. The environmental NO levels were less than 0.06 ppm and NO2 less than 0.3 ppm throughout the treatment, well within the safety margin. On day 152, the patient succumbed to hypoxemia and heart failure. The use of a nasopharyngeal NO delivery system without sedation, as an alternative to endotracheal intubation with sedation, was a practical method in treating a patient with PH while maintaining a certain quality of life for the patient and the family.

Administration, Inhalation↗
PubMed1998

Effects of exercise on bone mineral density in mature osteopenic rats.

Dual-energy X-ray absorptiometry (DXA) was used to examine the effects of quantitative application of treadmill running exercise on bone mineral density (BMD) of the tibia and the fourth and fifth lumbar (L4 + L5) vertebrae in mature osteopenic rats. Twenty 37-week-old rats with bone loss, resulting from feeding a relatively low calcium diet for 14 weeks after ovariectomy at the age of 23 weeks, were divided into four groups of five rats each according to the intensity and duration of the exercise: 12 m/minute, 1 h/day in group EX1; 18 m/minute, 1 h/day in group EX2; 12 m/minute, 2 h/day in group EX3; and sedentary control in group CON. With a standard calcium diet, the exercise was performed 5 days a week for 12 weeks, and the BMD of both the right tibia and the L4 + L5 vertebrae was measured using DXA at weeks 0, 4, 8, and 12. At the end of 12 weeks of exercise, the right femur and the L5 vertebra were dissected and the mechanical strength was measured using a three-point bending test and a compression test, respectively. After 12 weeks of exercise, a significant increase in the tibial BMD was observed in only group EX1 compared with that in group CON (p = 0.0039, by two-way analysis of variance). However, any significant increase in the L4 + L5 vertebral BMD was not observed in any exercise groups compared with that in the control group. While a maximum breaking force of the femoral shaft in group EX1 was significantly greater than that in group CON (p < 0.05, by Mann-Whitney's U-test), that in groups EX2 and EX3 did not significantly differ from that in group CON. However, there was no significant difference in a maximum breaking force of the L5 vertebral body among all the exercise and control groups. These results indicated that the beneficial effects of treadmill running exercise under a standard calcium diet were recognized only in the weight-bearing bones of the mature osteopenic rats resulting from estrogen deficiency and inadequate calcium intake only when an optimal level of exercise was applied.

Absorptiometry, Photon↗
PubMed1998

Effect of increased physical activity on bone mineral density in postmenopausal osteoporotic women.

The effect of increased physical activity on bone mineral density (BMD) of the lumbar vertebrae was examined in postmenopausal osteoporotic women. Thirty-five postmenopausal women, aged 53-77 years, whose BMD in the lumbar vertebrae (L2-L4) measured by dual energy x-ray absorptiometry (Norland XR-26) was below (> 30%) the young adult mean, were divided into two groups: a control group of 20 women and an exercise group of 15 women. The physical exercise consisted of daily outdoor walking and gymnastic training performed for 12 months. During the study period, all subjects were treated with calcium lactate, 2.0 g, and 1 alpha-hydroxyvitamin D3, 1 microgram, daily. Initial L2-L4 BMD was 0.611 +/- 0.045 (mean +/- SEM) g/cm2 in the control group and 0.606 +/- 0.066 g/cm2 in the exercise group (NS). In the control group, the BMD changes were -0.54 +/- 0.58% (mean +/- SEM) at 6 months and +1.00 +/- 1.29% at 12 months, compared to the baseline (P = 0.3424, by oneway ANOVA). In the exercise group, however, the changes were +1.78 +/- 0.90% and +4.48 +/- 0.93%, respectively (P = 0.0305, by two-way ANOVA). These data suggest that increased physical activity consisting of daily outdoor walking and gymnastic training can be useful in increasing lumbar BMD in postmenopausal osteoporotic women on calcium and vitamin D3 supplementation.

Aged↗
PubMed1998

Effects of moderate intensity exercise on tibial bone mass in mature ovariectomized rats: bone histomorphometry study.

The effects of moderate intensity exercise of different duration on the cancellous and cortical bone mass of the tibia were investigated in mature ovariectomized rats by bone histomorphometry. A total of twenty 23-week-old female Wistar rats were used in this study. Ovariectomy (OV) was performed on 15 animals, and they were divided into three groups of five animals each: an OV group, an OV + exercise for 30 min a day (EX30) group and an OV + EX60 group. The other 5 animals served as a sham-operated (SH) control group. The exercise consisted of treadmill running at 16 m/min and was performed 5 days a week for 12 weeks after the operation. After 12 weeks of exercise, bone histomorphometry was used to evaluate the cancellous bone (secondary spongiosa) of the proximal tibia and the cortical bone of the tibial shaft. The OV group showed a significant decrease in cancellous bone volume, with increased resorption and formation, compared to the SH group (P < 0.01). Although the OV + EX30 group showed a significant increase in cancellous bone volume, with decreased resorption and increased osteoblastic activity, compared to the OV group (P < 0.05), cancellous bone volume in the OV + EX30 group remained significantly lower than that in the SH group (P < 0.05). There was not a significant difference in cortical bone area between the OV group and the SH group, whereas the OV + EX30 group showed a significant increase in cortical bone area, with decreased resorption on the endosteal surface, compared to the OV group (P < 0.05). There were no significant differences in cancellous bone volume or cortical bone area between the OV group and the OV + EX60 group. The data suggest that moderate intensity exercise of appropriate duration may attenuate ovariectomy-induced cancellous bone loss and increase cortical bone mass in mature ovariectomized rats.

Animals↗