This study was undertaken to examine the role of the afferent and efferent pathways of the lumbosacral spinal nerve roots in the tonic control of bladder activity. Changes of isovolumetric bladder activity were recorded in 21 sympathectomized female rats under urethane anesthesia following transection of the dorsal (DRT) and ventral (VRT) lumbosacral spinal roots, and after intraperitoneal administration of hexamethonium. DRT altered the baseline intravesical pressure in a bladder volume-dependent manner in each animal. The percent change of baseline pressure after VRT following DRT was also dependent upon bladder volume. The percent change of baseline pressure after VRT alone was similarly dependent on bladder volume, but not after VRT followed by DRT. The percent change of baseline intravesical pressure (y)(-9 to +8 cm H2O, -56 to +46%) after DRT and VRT depended upon bladder volume (x)(y = 44.7 x -40.4) in all rats. Hexamethonium increased the amplitude of small myogenic bladder contractions after DRT and VRT. In conclusion, the bladder is tonically excited or inhibited by a local reflex pathway and by a parasympathetic reflex pathway that depends on connections with the lumbosacral spinal cord and the pelvic nerves. Both reflex mechanisms are influenced by bladder volume.
We investigated whether PKA-induced phosphorylation was involved in regulation of hyperpolarization-activated current (Ih) in rat dorsal root ganglion (DRG) cells. We examined the effect of the catalytic subunit of PKA (PKAc) on Ih and confirmed an effect of PKAc on Ca2+ channel currents carried by Ba2+ (IBa) in identical neurons as a positive control of PKA activity. After the start of recording, amplitudes of IBa gradually decreased (rundown). An intracellular application of ATP reduced the rundown of IBa and induced a depolarizing shift of Ih activation. The former was partially reversed by PKI but the latter was not affected. An intracellular application of PKAc also prevented the rundown of IBa and this effect was potentiated by okadaic acid (OA). The application of PKAc and OA in combination did not change the electrophysiological properties of Ih although a potentiating effect on IBa was observed in the same neurons. The application of 2-mM ATP in addition to PKAc and OA did not result in an additional potentiation of IBa, but shifted the activation curve of Ih positively. These results suggested that PKA-induced phosphorylation was not involved in the modulatory mechanisms of Ih in rat DRG neurons.
We have examined the morphological changes in chondrocytes after exposure to experimental hypergravity. Tibial epiphyseal cartilages of 17-days-old mouse fetuses were exposed to centrifugation at 3G for 16 h mimicking hypergravitational environment (experimental group), or subjected to stationary cultures (control group). Centrifugation did not affect the sizes of epiphyseal cartilage, chondrocyte proliferation, type X collagen-positive hypertrophic zone, and the mRNA expressions of parathyroid hormone-related peptide and fibroblast growth factor receptor III. However, centrifuged chondrocytes showed abnormal morphology and aberrant spatial arrangements, resulting in disrupted chondrocytic columns. Through histochemical assessments, actin filaments were shown to distribute evenly along cell membranes of control proliferative chondrocytes, while chondrocytes subjected to centrifugal force developed a thicker layer of actin filaments. Transmission electron microscopic observations revealed spotty electron-dense materials underlying control chondrocytes' cell membranes, while experimental chondrocytes showed their thick layer. In the intracolumnar regions of the control cartilage, longitudinal electron-dense fibrils were associated with short cytoplasmic processes of normal chondrocytes, indicating assumed cell-tomatrix interactions. These extracellular fibrils were disrupted in the centrifuged samples. Summarizing, altered actin filaments associated with cell membranes, irregular cell shape and disappearance of intracolumnar extracellular fibrils suggest that hypergravity disturbs cell-to-matrix interactions in our cartilage model.
An association between ambient air pollution and reduced cardiac autonomic function assessed by heart rate variability (HRV) mainly in elderly persons has been suggested by a number of epidemiological studies, but the link between the HRV and pulmonary function in humans remains unknown although such air pollution should primarily affect pulmonary function. To clarify this link, pulmonary ventilation parameters such as oxygen uptake (VO2) and carbon dioxide output (VCO2), as well as the HRV with spectral analysis (high- and low-frequency components of HRV, i.e., CCVHF and CCVLF, reflecting cardiac parasympathetic and sympathetic activities, respectively), were measured in 66 healthy women aged 19-20 years after an overnight fast of 12 h. Significant correlations were found between the CCVHF of HRV and both the end-tidal carbon dioxide concentration (FETCO2) and gas exchange ratio (VCO2/VO2) in the subjects (partial correlation coefficients r = 0.354 and 0.320, respectively), whereas there was no significant connection between the FETCO2 and the VCO2/VO2. Similarly, the CCVLF correlated significantly with the resting tidal volume of lung (r = 0.364). These findings suggest that resting pulmonary ventilation function interacts with cardiac autonomic function assessed by the HRV, at least in healthy young adults, which may be useful for explaining the pathophysiology concerning the short-term effect of air pollution such as fine particulate matter on cardiovascular function.
We investigated the factors related to nocturnal urination that was not considered bothersome by comparing various parameters between subjects who felt nocturnal urination as bothersome and those who did not. A total of 94 persons (50 males and 44 females) were enrolled. They urinated ≥ once per night. Each subject's perception of nocturnal urination was examined, and the subjects were divided into a bothersome group and a non-bothersome group. Blood biochemical data and urinary condition were compared between the two groups and various subgroups. There were 60 subjects (56 ± 17 years old) in the non-bothersome group, and 34 subjects (57 ± 17 years old) in the bothersome group. The serum melatonin level was significantly lower and the total score of the International Prostatic Symptom Score questionnaire (IPSS) and the quality of life (QOL) score were significantly higher in the bothersome group than in the non-bothersome group. Among 50 subjects with nocturnal urination ≥ twice per night, the serum melatonin level was also significantly lower and the QOL score was significantly higher in the bothersome group than in the nonbothersome group. In conclusion, nocturnal urination might be not considered bothersome when subjects maintain sufficient levels of melatonin.
We aimed to histologically elucidate whether bioresorbable plates (DeltaSystem®) can induce cortical bone formation, which is essential for long-lasting bone augmentation. Standardized bone defects in rat calvariae were covered with a convexly-shaped DeltaSystem® plate, and then processed for histological observations. At 1 week, alkaline phosphatase-positive osteoblasts were seen in the newly-formed bone extending from the cavity's bottom, indicating accelerated osteogenesis. A thick layer of soft connective tissue positive for periostin, a hallmark of periosteum, covered this new bone. At 2 weeks, a spongy bone had filled the cavity up to half its height. The inner layer of the soft tissue facing the spongy bone revealed abundant periostin and osteopontin, and had many tartrate-resistant acid phosphatase-positive osteoclasts. At 4 weeks, this layer had given rise to thin new bony matrices without relation to the spongy bone arising from the cavity. These bone matrices had been thickened by 8 weeks, and turned into a thick cortical bone outlining the regenerated bone at 12 weeks. Thus, our study has provided histological evidences of cortical osteogenesis when DeltaSystem® plates are used for bone augmentation procedures.