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131.
Ryohei Katoh Koichi Suzuki Akihiro Hemmi Akira Kawaoi 《Virchows Archiv : an international journal of pathology》1993,422(4):301-306
To elucidate the significance and nature of calcium oxalate crystals in the thyroid, we studied these crystals clinicopathologically and immunohistochemically in 182 normal thyroids from patients autopsied within 5 h of death. Under polarized light, calcium oxalate crystals showed brilliant birefringence and were invariably found within the colloid. The crystals were found in 73.1% of all cases but were more prevalent and denser in older individuals, with the highest prevalence (85.2%) being observed in those over 70 years of age. No crystals were seen in those under 10 years of age. Although underlying diseases seemed to have little influence, post-mortem delay apparently affected the prevalence and density of occurrence since the crystals tended to disappear with hours after death. An immunohistochemical study using anti-thyroid hormone antibodies revealed that the crystals were within negatively or weakly stained colloid and were not common in strongly stained colloid. These findings support the hypothesis that the occurrence of calcium oxalate crystals in normal human thyroid is associated with a low functional state of the thyroid follicles. 相似文献
132.
Yoshio Maruyama 《Pflügers Archiv : European journal of physiology》1986,407(5):561-563
A phase-sensitive detection method in combination with whole-cell voltage-clamp was applied to exocrine pancreatic acinar cells from rat. The results have shown that cell-aialysis with a solution containing 5×10–7 M Ca2+ induces stp-wise changes in cell capacitance. The size distribution of increasing and decreasing capacitance steps is compatible with the idea that these capacitance steps are the results of individual granular fusion and retrieval events. This method may enable experiments studying the exo-and endo-cytotic mechanisms in morphologically polarized secretory cells. 相似文献
133.
J. Walden H. Pockberger E. -J. Speckmann H. Petsche 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1986,64(3):607-609
Summary Epileptic activity was elicited in the rat's motor cortex by local application of penicillin. At the neuronal level it consisted
of typical paroxysmal depolarization shifts. The calcium agonist BAY K 8644 was injected into neurons showing such a discharge
pattern. The application of this drug increased amplitude and afterdepolarization of paroxysmal neuronal depolarizations. 相似文献
134.
C. Strube M. Beurg D. Georgescauld R. Bournaud T. Shimahara 《Pflügers Archiv : European journal of physiology》1994,427(5-6):517-523
Spatio-temporal changes in the intracellular calcium concentration [Ca2+]i of dissociated mice myotubes from 14-day and 18-day-old fetuses were studied using digital imaging analysis of the Ca2+ indicator fura-2. Myotubes from 18-day-old fetuses displayed a transient [Ca2+]i increase upon electrical stimulation either in nominally calcium-free external solution or in Krebs solution containing 100 M lanthanum. Thus, at this developmental stage, membrane depolarization appears to increase [Ca2+]i by stimulating Ca2+ release from the sarcoplasmic reticulum independently of extracellular Ca2+ influx. Similarly, myotubes from 14-day-old fetuses also showed a calcium transient upon electrical stimulation in Krebs solution. However, in 46% of these myotubes the calcium transient was abolished when Ca2+ entry through calcium channels was suppressed. 相似文献
135.
Role of actin microfilament in osmotic stretch-induced increase of voltage-operated calcium channel current in guinea-pig gastric myocytes 总被引:5,自引:0,他引:5
Wen Xie Xu Sung Joon Kim Insuk So K. W. Kim 《Pflügers Archiv : European journal of physiology》1997,434(4):502-504
Using the whole-cell patch clamp technique, the role of actin microfilament in hyposmotic increase of voltage-operated calcium
channel current (I
Ba) was studied in guinea-pig gastric myocytes. Hyposmotic superfusate (212 mOsm) increased peak I
Ba amplitude by 32.7 ± 6.5%; when cytochalasin-D (Cyt-D, 20 μM), an actin cytoskeleton disruptor, was used, an increase of only
9.7 ± 3.1% was seen. I
Baresponse to osmotic stress was potentiated (45.1 ± 4.1% increase) by 20 μM phalloidin, an actin microfilament stabilizer.
However, colchicine (100 μM), an microtubule cytoskeleton disruptor, had no effect on either I
Ba or its response to hyposmotic solution. Phalloidin also induced a rightward shift of the I/V relationship of I
Ba, while Cyt-D itself had no effect. These results suggest that actin cytoskeleton may mediate hyposmotic stretch-induced I
Ba increase in gastric smooth muscle.
Received: 26 March 1997 / Received after revision: 28 May 1997 / Accepted: 3 June 1997 相似文献
136.
Isolation and radiation hybrid mapping of a dinucleotide repeat polymorphism at the human calcium-sensing receptor (CASR) locus 总被引:2,自引:0,他引:2
Kazuhiro Tsukamoto Ikuyo Watanabe Tadayoshi Shiba M. Emi 《Journal of human genetics》1998,43(4):280-282
Calcium-sensing receptor (CASR) in parathyroid gland regulates calcium homeostasis by sensing decreases in extracellular
calcium levels and effecting an increase in secretion of parathyroid hormone. A polymorphic dinucleotide (CA) sequence was
isolated from a genomic clone containing the human CASR gene and was mapped to 3q13.3–q21. This polymorphism will be useful in the genetic study of disorders affecting calcium metabolism,
such as hypercalcemia, hypocalcemia, osteoporosis, hyperparathyroidism, and hypoparathyroidism.
Received: June 2, 1998 / Accepted: June 24, 1998 相似文献
137.
Here, functional AMPA/kainate receptors in human embryonic (5.5–7.5 gestational weeks) and foetal (8–10 gestational weeks) central nervous system tissue, shown by the cobalt labeling method, are reported. Specific agonist-induced cobalt incorporation was detected in brainstem and spinal cord cells, even in the youngest embryo studied. T-AMPA or kainate, but also vegetal toxins such as L-BOAA or acromelate, induced accumulation of cobalt. In contrast, no labeling was observed after exposure to KCl or NMDA. Cobalt labeled cells were particularly prominent in motor regions of brainstem and spinal cord. Co-application of the diuretic agent cyclothiazide, a desensitization blocker at AMPA receptors, dramatically increased the number of stained cells, which was particularly obvious in sensory regions, suggesting different receptor properties in motor versus sensory regions. This is the first study providing evidence for functional AMPA/kainate receptors, permeable to divalent cations, in brainstem and spinal cord at an early stage of human central nervous system development. Since many developmental processes are influenced by the modulation of cytosolic calcium, exposure at critical stages of embryogenesis to food or drug substances modifying the activity of AMPA/kainate receptors may alter brain development. 相似文献
138.
Balvinder S. Jassar Peter A. Smith 《Pflügers Archiv : European journal of physiology》1991,419(5):478-485
The afterhyperpolarization (AHP) which follows the action potential (AP) in bullfrog sympathetic ganglion B-cells involves activation of Ca2+-sensitive K+ conductances following Ca2+ influx via Ca2+ channels. The duration of AHPs evoked at 2-s stimulus intervals were 70.05±3.76% of those evoked at 90-s stimulus intervals (n=35). Since there was no consistent effect of ryanodine (5 M), ruthenium red, (300 M) or dantrolene Na (35 M) on this frequency dependence, it is unlikely to result from release of Ca2+ from intracellular stores. Ca2+ currents (I
Ca, studied by means of the whole-cell patch-clamp technique, exhibited a slow frequency dependence as a result of a slow inactivation process which was independent of Ca2+-induced I
Ca inactivation and I
Ca run-down. There was excellent correlation (r=0.964) between the estimated changes in Ca2+ influx and the expected activation of the Ca2+-sensitive K+ current, I
AHP. This result is consistent with the hypothesis that the frequency dependence of the AHP is a consequence of the slow inactivation of I
Ca. 相似文献
139.
K. B. Walsh S. H. Bryant A. Schwartz 《Pflügers Archiv : European journal of physiology》1987,409(1-2):217-219
The calcium channel-inhibiting drugs nitrendipine and diltiazem represent two important classes of organic calcium antagonists. In the present study, the effect of these drugs on calcium currents and charge displacement currents in bullfrog semitendinosus muscle fibers was examined using a vaseline gap voltage clamp. Nitrendipine (10 M) reduced the quantity of charge that moved both during the ON phase (QON) and the OFF phase (QOFF) of charge movement. This action appeared to be most selective for QON. However, at this same concentration, nitrendipine had no blocking action on inward calcium currents. In contrast to these findings, diltiazem blocked calcium currents in a concentration-dependent manner, while slightly increasing the quantity of charge moved during QON and QOFF. The enhancement of charge movement by diltiazem resulted from two actions. First, diltiazem shifted the voltage-dependence of charge movement to more negative potentials. Second, diltiazem increased the maximum amount of charge moved. (Supported by NIH NS 03178 and HL 07382.) 相似文献
140.
Schaefer M 《Pflügers Archiv : European journal of physiology》2005,451(1):35-42
Mammalian homologues of the Drosophila melanogaster transient receptor potential (TRP) channels are the second largest cation channel family within the superfamily of hexahelical cation channels. Most mammalian TRP channels function as homooligomers and mediate mono- or divalent cation entry upon activation by a variety of stimuli. Because native TRP channels may be multimeric proteins of possibly complex composition, it is difficult to compare cation conductances in native tissues to those of clearly defined homomeric TRP channel complexes in living cells. Therefore, the possibility of heteromeric TRP channel assembly has been investigated in recent years by several groups. As a major conclusion of these studies, most heteromeric TRP channel complexes appear to consist of subunit combinations only within relatively narrow confines of phylogenetic subfamilies. Although the general capability of heteromer formation between closely related TRP channel subunits is now clearly established, we are only beginning to understand whether these heteromeric complexes are of physiological significance. This review summarizes the current knowledge on the promiscuity and specificity of the assembly of channel complexes composed of TRPC-, TRPV- and TRPM-subunits of mammalian TRP channels. 相似文献