Corneal D.C. recordings of slow ocular potential changes such as the ERG c-wave and the light peak in clinical work

A set-up for D.C. recordings of slow ocular potentials such as the c-wave of the electroretinogram (ERG) as well as the fast oscillation (FO), the light peak (LP) and the dark trough (DT) in both clinical and experimental work is described. It includes matched calomel half-cells connected by saline-agar bridges to a corneal contact lens on the eye and a reference chamber on the forehead, a low-drift differential-input D.C. amplifier, an A/D converter, a computer, a thermoprinter, a flexible disc memory, a plotter, and a device for light stimulation controlled by the computer.Examples of the usefulness of the set-up in clinical work are shown in the form of D.C. c-wave ERGs of normal subjects as well as of patients with vitelliform macular degeneration, choriocapillaris atrophy, and retinitis pigmentosa. The direct corneal recording of the FO and LP is demonstrated as well. The different origins of the standing potential (SP) of the eye, the ERG c-wave, the FO and the LP are reviewed briefly.     

Results of 24-h manometric recording of colonic motor activity with endoluminal instillation of bisacodyl in patients with severe chronic slow transit constipation

The aims of this study were to assess the prevalence of manometric colonic abnormalities and to evaluate the motor effect of intraluminal bisacodyl in a cohort of refractory constipated patients. Twenty-four hour colonic motility recordings were performed in 40 patients referred for a severe intractable chronic constipation. At the end of each recording session the motor effects of the endoluminal instillation of 10 mg bisacodyl were assessed. These patients were compared with 20 healthy subjects. The number of high-amplitude propagating contractions (HAPC) was significantly decreased in patients with slow transit constipation (12 +/- 11.6 vs 1 +/- 8.6, P < 0.001). Based on manometric patterns four groups of patients were isolated. Ten patients had no spontaneous HAPC, no food-induced colonic motor response and significantly lower colonic activity in transverse colon (374 +/- 1220 vs 3249 +/- 3458, P < 0.05). Five patients had significantly increased sigmoid segmental motility (20298 +/- 6364 vs 88780 +/- 3643, P < 0.001) and eight patients had significantly lower number of HAPC without other manometric abnormalities while 17 patients had normal colonic motility recordings. Endoluminal bisacodyl was able to induce HAPCs in all groups of patients. Patients with severe slow transit refractory constipation represented a heterogeneous group and endoluminal bisacodyl was able to promote a propagated motor activity in a majority of patients even in those suspected of having an inert colon.     

A slim needle-shaped multiwire microelectrode for intracerebral recording

The construction of a needle-shaped multiwire microelectrode is described. It can be made with simple mechanical tools. The presented electrode assembly consists of 12 insulated nichrome wires (core diameter 25 μm) which are embedded in epoxylite resin. The straight-cut wire tips are aligned lengthwise and have a relative spacing of 150 μm. Outer dimensions vary from 100 × 180 μm at the level of the 1st electrode channel, to 100 × 100 μm at the level of the 12th channel at the tip. The configuration of this electrode was determined by its application: the laminar analysis of evoked potentials in the cortex of the rat. However, the number of channels, the diameter of the (nichrome) wire which determines the surface area of these channels, and the channel spacing can be easily adjusted during construction to meet other experimental requirements, such as the recording of single-unit activity. The electrode which is composed of biocompatible materials is suited for the study of field potentials and multiple-unit activity, in both acute and chronic experiments, and can be used repeatedly. To demonstrate the performance of the electrode assembly, a depth profile of field potentials is presented, accompanied by the corresponding current source density distribution. The potentials were recorded in the somatosensory cortex of the rat following stimulation of the median nerve under ketamine anesthesia.     

Interrelationship between secretion, protein phosphorylation and intracellular Ca2+ concentration in platelets stimulated by thrombin or thromboxane A2 analogue

The interrelationship between ATP-secretion, protein phosphorylation and intracellular Ca²⁺ concentration ([Ca²⁺]i) was studied in both ³²P and quin 2 loaded human platelets stimulated by thrombin or thromboxane A₂ analogue (STA₂). In platelets stimulated by thrombin, the degree of 47,000 dalton polypeptides (P47) phosphorylation was observed in completely dose-related manner, regardless of the amount of [Ca²⁺]i. In the same condition, the degree of myosin light chain (P20) phosphorylation, however, was well correlated with ATP secretion and [Ca²⁺]i, when platelets were stimulated by lower dose of thrombin. The similar results were obtained in platelets stimulated by STA₂. These findings suggested that P20, but not P47, phosphorylation in activated platelets is mediated by a rise of [Ca²⁺]i and is well correlated with the secretory reaction. It was unlikely that P47 phosphorylation plays any role in promoting platelet activation.     

Inhibition of N-, P/Q- and other types of Ca channels in rat hippocampal nerve terminals by the adenosine A1 receptor

The effects of the adenosine A₁ receptor agonist, N⁶-cyclopentyladenosine (CPA), on both the increase in intracellular free Ca²⁺ concentration ([Ca²⁺]_i) and on the release of endogenous glutamate in rat hippocampal synaptosomes were studied. The inhibitory effect of CPA on the increase in [Ca²⁺]_i stimulated with 4-aminopyridine was neutralized by the adenosine A₁ receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). The inhibitory effect of CPA was greater in synaptosomes from the CA1 subregion than in whole hippocampal synaptosomes. The inhibitory effects of both CPA and of the Ca²⁺ channel blockers, ω-conotoxin GVIA, ω-conotoxin MVIIC or ω-conotoxin GVIA plus ω-conotoxin MVIIC, were greater than those caused by the Ca²⁺ channel blockers. The release of endogenous glutamate was inhibited by 41% by CPA. The inhibition observed when CPA and ω-conotoxin GVIA or CPA and ω-conotoxin MVIIC were present was also greater than the inhibition by the Ca²⁺ channel blockers alone. The presence of both ω-conotoxin GVIA and ω-conotoxin MVIIC did not completely inhibit the release of glutamate, and CPA significantly enhanced this inhibition. The membrane potential and the accumulation of [

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]tetraphenylphosphonium of polarized or depolarized synaptosomes was not affected by CPA, suggesting that adenosine did not increase potassium conductances. The present results suggest that, in hippocampal glutamatergic nerve terminals, adenosine A₁ receptor activation partly inhibits P/Q- and other non-identified types of Ca²⁺ channels.     

The shell region of the nucleus ovoidalis: a subdivision of the avian auditory thalamus.

The connectivity of a region surrounding the established thalamic auditory nuclei, n. ovoidalis (Ov) and n. semilunaris parovoidalis (SPO), was explored in the ring dove by using the anterograde tracers, Phaseolus vulgaris leucoagglutinin (PHAL) and biocytin, and the retrograde tracer, fluorogold. The Ov-SPO surround received a projection from a cell group along the interface of the auditory midbrain and the n. intercollicularis, as revealed with PHAL and biocytin, and was composed of neurons exhibiting a common morphology. These features and the presence of overlapping projections from different portions of the Ov-SPO surround suggest that this region comprises a functionally discrete area, which we term the Ov shell. Single unit recording within the shell established the existence of acoustically responsive units. Both PHAL and fluorogold labeling revealed a robust projection from the Ov shell to the caudomedial hypothalamus. Major telencephalic projections of the shell terminated within the ventral paleostriatal complex, "end-zones" of the field L, the caudomedial hyperstriatum ventrale, and regions immediately dorsal and lateral to the auditory neostriatum. Except for a portion of the shell bordering medial ovoidalis, PHAL injections into the shell also labeled fibers within the caudolateral neostriatum and along the lateral neostriatal rim. The connectivity of the Ov shell suggests that this region may integrate auditory pathways with brain regions associated with endocrine mediated behavior. In addition, the shell may constitute a source of converging input to several levels of central auditory pathways.     

Spontaneous activity of dorsal raphe neurons during defensive and offensive encounters in the tree-shrew

The general characteristics of these telemetrically recorded neurons of dorsal raphe, such as firing rate under nembutal anesthesia, reaction to illumination changes or acoustic stimuli were comparable to those in the literature. The firing rate of the dorsal raphe neurons increased during defensive encounters (+51%±29% S.D.; p<0.005) and defensive fights (+113%±91% S.D.; p<0.02) as compared to the neuronal activity of the undisturbed resting animal. The fearful interaction of the animal with the experimenter led to the strongest increase in the firing rate (+187%±114% S.D.; p<0.002) in all animals tested. The offensive animal showed decreased neuronal activity during offensive encounters (?21%±13% S.D.; p<0.02) and offensive fights (?42%±17%S.D.; p<0.05) as compared with the neuronal activity of the undisturbed resting animal. These findings indicate the crucial importance of the animals appraisal of the situational contex for the activity of dorsal raphe neurons.     

大鼠运动皮层投射神经元与Parvalbumin免疫阳性神经纤维终末的关系──免疫荧光、Confocal显微镜观察

Parvalburnin是细胞内一种钙结合蛋白。同时又可作为中枢神经系统内与GABA共存的神经元亚群的特异标记物，主要标记篮状及苔烛细胞。用PAP方谈染色可见大鼠Parvalbumin免疫阳性神经终末在运动皮层锥体神经元胞体周围形成包篮现象，但因该方法的局限性．较难明确二者的关系。为进一步了解Parvalbumin阳性终未在锥体神经元脑体、树突与轴突整体上的分布状况以及运幼皮层内不同传出神经元是否均接受同样的支配，本实验利用FastBlue送行标记、固定脑片细胞内注入LueiferYellow结合免疫荧光、Confocal显微镜观察，研究运动皮层内皮质丘脑（束旁核）、皮质效状体及皮质脊髓三种投射神经元与Parvalbumin阳性终末的关系。通过1．μ连续扫描图像的分析及立体对观察，Parvalbumin阳性终末清晰可见，与LuciferYellow标记的锥体细胞的关系也容易辨别．在三种投射神经元胞体上均可见Parvalbumin阳性终末包绕，形成明显包篮现象，但三种神经元上的终末数未见明显区别·阳性终未还分布于近端树突上，距胞体越远越稀疏：但在距脑体50μm以上的顶树突、30μm以上的基树突及其二、三级分枝的远端树突上仍偶有终末分布．此外，三种神经元轴突起始段上也有少量终末接触，但未形成明显的cartridge现象．这一结果揭示，Parvalb     

Amiloride-blockable Ca2+-activated Na+-permeant channels in the fetal distal lung epithelium

The Na⁺ transport function of alveolar epithelium represents an important mechanism for clearance of fluid in air space at birth. I observed the activity of two types of amiloride-blockable Na⁺-permeant cation channels in the apical membrane of fetal distal lung epithelium cultured on permeable filters for 2 days after harvesting of the cells from Wistar rats of 20 days' gestation (term = 22 days). One type was a nonselective cation (NSC) channel and had a linear current/voltage (I/V) relationship with a single-channel conductance of 26.9 ± 0.8 pS (n = 5). The other type was highly Na⁺ selective (i.e. Na⁺ channel) and had an inwardly rectifyingI/V relationship with a single-channel conductance of 11.8 ± 0.2 pS (n = 5) around resting membrane potential. The NSC channel was more frequently observed (1.37 ± 0.15 per patch membrane;n = 73) than the Na⁺ channel (0.15 ± 0.40 per patch membrane;n = 73). However, the open probability of the NSC channel was smaller than that of the Na⁺ channel. Both types of the channels were activated by cytosolic Ca²⁺, however the sensitivity to cytosolic Ca²⁺ was much higher in the Na⁺ channel than in the NSC channel. Furthermore, both types of the channels were blocked by amiloride or benzamil. The half-maximal inhibitory concentration (IC₅₀) of amiloride or benzamil of the Na⁺ channel was 1–2 M, while that of NSC channel was less than 1 M. Both channels were activated by insulin.