Properties of contractions induced by ouabain and K+-free solution in guinea pig taenia coli

The properties of contractions induced by ouabain and by K depletion were studied in comparison with those induced by other stimulants in guinea pig taenia coli. Ouabain 7.5 × 1o^?6 M and K depletion produced biphasic contractions with similar time courses. Both contractions were slightly inhibited by low (0.25 mM) and high (7.5 mM) Ca concentrations, while the high K contraction was strongly inhibited by low Ca and potentiated by high Ca. Contractions induced by ouabain and K depletion were highly sensitive to lowering of the temperature and abolished at 15°C, although contractions induced by carbachol 1.1 × 10^?7 M and histamine 5 × 10^?7 M were still observed below 15°C. In Cl deficient solution substituted by SO₄ or propionate, contractions induced by ouabain and K depletion were potentiated, while contractions induced by high K, carbachol and histamine were suppressed. These results indicate a striking similarity between contractions induced by ouabain and K depletion suggesting a common mechanism for both contractions.     

Potassium recycling pathways in the human cochlea

OBJECTIVES/HYPOTHESIS: Potential pathways for recycling potassium (K+) used in the maintenance of inner ear electrochemical gradients have been elucidated in animal models. However, little is known about K+ transport in the human cochlea. This study was designed to characterize putative K+ recycling pathways in the human ear and to determine whether observations from animal models can be extrapolated to humans. STUDY DESIGN: A prospective laboratory study using an immunohistochemical approach to analyze the distribution of key ion transport mediators in the human cochlea. METHODS: Human temporal bones were fixed in situ within 1 to 6 hours of death and subsequently harvested at autopsy. Decalcification was accomplished with the aid of microwaving. Immunohistochemical staining was then performed to define the presence and cell type-specific distribution of Na,K-ATPase, sodium-potassium-chloride cotransporter (NKCC), and carbonic anhydrase (CA) in the inner ear. RESULTS: Staining patterns visualized in the human cochlea closely paralleled those seen in other species. Anti-Na,K-ATPase stained strongly the basolateral plasma membrane of strial marginal cells and nerve endings underlying hair cells. This antibody also localized Na,K-ATPase to type II, type IV, and type V fibrocytes in the spiral ligament and in limbal fibrocytes. NKCC was present in the basolateral membrane of strial marginal cells as well as in type II, type V, and limbal fibrocytes. Immunoreactive carbonic anhydrase was present in type I and type III fibrocytes and in epithelial cells lining Reissner's membrane and the spiral prominence. CONCLUSIONS: The distribution of several major ion transport proteins in the human cochlea is similar but not identical to that described in various rodent models. These results support the presence of a complex system for recycling and regulating K+ homeostasis in the human cochlea, similar to that described in other mammalian species.     

一种高灵敏度测定水中游离氯的新方法

目的 建立高灵敏度测定水中游离氯的新方法。方法 采用中性水溶液中游离氯（Cl2)催化过氧化氢（H2O2）氧化品红的褪色吸光度法测定水中Cl2。结果 方法操作简便易行,灵敏度高,测定范围为0.015-1.0μg/10ml,回收率99.0%-107%。结论 本法可用于饮用水中Cl2的快速测定。     

Epithelial Ion Transport in the Heal J-Pouch after Proctocolectomy in the Rat

In ulcerative colitis and polyposis coli, creation of an ileal pouch with ileoanal anastomosis after proctocolectomy has become a common surgical method. The aim of our study was to characterize the adaptation of the epithelial ion transport function in the pouch by using electrophysiologic techniques. Proctocolectomy and ileoanal anastomosis was performed in rats either with (pouch) or without (control) creation of an ileal J-pouch. To characterize the epithelial barrier function, impedance analysis was performed 6 months after surgery. Epithelial resistance was 29 ± 2 Ω · cm² in controls and was unchanged in the pouch (28 ± 4 Ω · cm²; NS). In contrast, subepithelial resistance increased from 33 ± 3 Ω · cm² to 54 ± 5 Ω · cm² (p < 0.01) owing to work hypertrophy of the muscle layers in the pouch. To detect changes in net ion transport, ion tracer fluxes were measured in the Ussing chamber. In control ileum, absorptive net Na and Cl fluxes of similar magnitude were present, indicating that electroneutral NaCl absorption was the predominant ion transport system. Neither I_sc nor net Na and Cl fluxes were significantly altered in the pouch. Glucose-coupled Na absorption was measured as the 3-o-methyl-glucose-induced increase in I_sc. K_m remained unaltered, while V_max decreased from 7.5 ± 2.1 μeq · h^-1 cm^-2 in controls to 1.7 ± 0.8 μeq · h^-1 cm^-2 (p < 0.05) in the pouch. Then, maximal transport capacity for electrogenic Cl secretion was measured as the Cl-induced increase in I_sc blockable by serosal bumetanide (in the presence of theophylline and prostaglandin E₁). K_m remained unaltered, while V_max decreased from 4.2 ± 0.7 μeq · h^-1 cm^-2 in controls to 1.9 ± 0.7 μeq · h^-1 cm^-2 (p < 0.05) in the pouch. Microdissection showed increased crypt depth and villus height in the pouch as seen in the early state of hyperregenerative transformation. We conclude that the mucosa of the pouch exhibits a hyperregenerative transformation. It is characterized by an impaired transport capacity for glucose-coupled Na absorption and, less pronounced, electrogenic Cl secretion, while the epithelial barrier function was unaffected. The adaptational pattern resembles that observed in the blind loop syndrome and may share common mechanisms—in particular, bacterial overgrowth. Thus, pouch creation can improve functional results of resective surgery due to an enlarged reservoir but is threatened by impaired mucosal function. A decrease in Na-glucose cotransport of the ileal mucosa after pouch creation could contribute to diarrhea in these patients.     

Na~+/H~+交换、Na~+/K~+/2Cl~-转运体抑制剂对缺血大鼠心脏保护作用的研究

目的　研究 Na+ /H+ 交换抑制剂阿米洛利 (Am iloride)、Na+ /K+ /2 Cl- 协同转运抑制剂呋塞米 (Furosemide)对长时间低温保存下离体大鼠心脏的保护作用。方法　建立 L angendorff及工作心脏灌注模型。实验组用 St.Thomas- 2 (STH- 2 )液 +阿米洛利 +呋塞米停搏并保存其中 ,对照组只用 STH - 2停搏、保存。置 7℃环境 5 h后恢复灌流。观察血流动力学、心肌酶学及超微结构的变化。结果　实验组冠状动脉流量 (CAF)、左心室收缩压 (L VSP)、左心室压力变化速率 (± dp/dt)的恢复率均优于对照组 (P<0 .0 1) ;肌酸磷酸激酶 (CPK)、乳酸脱氢酶 (L DH)漏出量明显少于对照组 (P<0 .0 5 ) ;心肌组织中 Na+ - K+ - ATP酶、Ca2 + - ATP酶和 Ca2 + - Mg2 + - ATP酶活力均显著高于对照组 (P<0 .0 1) ;实验组的心肌细胞超微结构得到较好的保护。结论　 Na+ /H+ 交换、Na+ /K+ /2 Cl- 协同转运抑制剂对缺血大鼠心肌具有明显保护作用     

Nuclear organization of cholinergic,catecholaminergic, serotonergic and orexinergic systems in the brain of the Tasmanian devil (Sarcophilus harrisii)

This study investigated the nuclear organization of four immunohistochemically identifiable neural systems (cholinergic, catecholaminergic, serotonergic and orexinergic) within the brains of three male Tasmanian devils (Sarcophilus harrisii), which had a mean brain mass of 11.6 g. We found that the nuclei generally observed for these systems in other mammalian brains were present in the brain of the Tasmanian devil. Despite this, specific differences in the nuclear organization of the cholinergic, catecholaminergic and serotonergic systems appear to carry a phylogenetic signal. In the cholinergic system, only the dorsal hypothalamic cholinergic nucleus could be observed, while an extra dorsal subdivision of the laterodorsal tegmental nucleus and cholinergic neurons within the gelatinous layer of the caudal spinal trigeminal nucleus were observed. Within the catecholaminergic system the A4 nucleus of the locus coeruleus complex was absent, as was the caudal ventrolateral serotonergic group of the serotonergic system. The organization of the orexinergic system was similar to that seen in many mammals previously studied. Overall, while showing strong similarities to the organization of these systems in other mammals, the specific differences observed in the Tasmanian devil reveal either order specific, or class specific, features of these systems. Further studies will reveal the extent of change in the nuclear organization of these systems in marsupials and how these potential changes may affect functionality.     

Gamma-ray energies in the decay of Cl

In order to resolve a long-standing discrepancy of some 30 standard deviations between the two most precise previously reported values of the γ-ray energies in the ³⁸Cl decays, we have undertaken a new precision measurement of the decay energies using a variety of different sources for energy calibration. The deduced energies from the present work are 1642.668±0.010 and 2167.395±0.010 keV. These results agree very well with one of the previous reports and disagree with the other.