NADPH diaphorase-positive neurons in the intracardiac plexus of human, monkey and canine right atria

Distribution of nitric oxide synthase in intracardiac ganglion cells located in human, monkey and canine right atria was histologically investigated using the reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase method and acetylcholinesterase histochemistry. In the intracardiac ganglion, many large neurons exhibited both positive reactions, whereas some of the NADPH diaphorase-positive small neuronal cells were shown with negative acetylcholinesterase reaction.     

Neurotensin immunoreactive structures in the human infant striatum, septum, amygdala and cerebral cortex

Neurotensin immunoreactive (NT-IR) neuronal perikarya are present in small numbers in the bed nucleus of the stria terminalis, lateral olfactory stria, substantia innominata, caudate nucleus and putamen of the human infant forebrain. Larger numbers of perikarya are present in the amygdala and related structures. NT-IR axons are present in the medial septal area, bed nucleus of the stria terminalis, caudate nucleus, putamen and amygdala. The cerebral cortex contains a rich network of NT axons with an accentuation in layer II. This network appears to be derived from bundles of axons which traverse the deep white matter from the thalamus.     

Inhibitory effect of a novel angiotensin II type 1 receptor antagonist RNH-6270 on growth of vascular smooth muscle cells from spontaneously hypertensive rats: different anti-proliferative effect to angiotensin-converting enzyme inhibitor.

The current study was undertaken to evaluate the anti-proliferative effect of a novel angiotensin II type 1 (AT1) receptor antagonist, RNH-6270, on exaggerated growth of vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR), in comparison with the effects of an angiotensin-converting enzyme (ACE) inhibitor. RNH-6270 and temocapril significantly inhibited basal DNA synthesis in VSMCs from SHRs in a dose-dependent manner, but not in cells from Wistar-Kyoto (WKY) rats. SHR-derived VSMC showed a hyperresponse of DNA synthesis to serum and angiotensin II compared with that of WKY rats-derived VSMC. RNH-6270 did not affect serum-stimulated DNA synthesis in VSMCs from both rat strains. RNH-6270 abolished angiotensin II-stimulated DNA synthesis in VSMC from both rat strains. RNH-6270 significantly inhibited proliferation of VSMC from both rat strains, but the ACE inhibitor temocapril did not exert such an effect. RNH-6270 decreased the specific binding of angiotensin II to VSMC in a competitive manner for angiotensin II receptors in both rat strains. RNH-6270 and temocapril significantly decreased the expression of growth factor mRNAs and proteins in VSMC from SHR, but not in cells from WKY rats. These results suggest that RNH-6270 is a potent AT1 receptor antagonist and has anti-proliferative effects on VSMCs from SHR, which was not seen with an ACE inhibitor. The growth inhibitory effect of RNH-6270 may be associated with the inhibition of growth factors via antagonism to AT1 receptors.     

Differential expression of five N-methyl-D-aspartate receptor subunit mRNAs in the cerebellum of developing and adult rats

Five N-methyl-D-aspartate (NMDA) receptor subunits have been identified thus far: NR1, NR2A, NR2B, NR2C, and NR2D. Here, we have analyzed the expression patterns of mRNAs for the NMDA receptor subunits in the developing and adult rats by in situ hybridization. The developmental changes of the expression patterns were most salient in the cerebellum. In the external granular layer, hybridization signals of mRNAs, for NR1, NR2A, NR2B, and NR2C appeared by postnatal day 3, but no NR2D mRNA was expressed at any developmental stage examined. The NR1 mRNA was expressed in all cerebellar neurons at all developmental stages examined. The signals for the NR2A mRNA appeared in Purkinje cells and granule cells during the second postnatal week. The signals for the NR2B mRNA in granule cells were seen transiently during the first 2 weeks after birth. The signals for NR2C mRNA appeared in granule cells and glial cells during the second postnatal week. The signals for NR2D mRNA appeared transiently in Purkinje cells during the first 8 postnatal days; in adult rats, these were seen in stellate and Golgi cells. In the cerebellar nuclei, mRNAs for NR1, NR2A, NR2B, and NR2D were more or less expressed on postnatal day 0, while expression signals for the NR2C mRNA were first detected in postnatal day 14. Thus, the most conspicuous changes of expression patterns were observed in the cerebellar cortex during the first 2 weeks after birth, when development and maturation of the cerebellum proceed most rapidly. © 1994 Wiley-Liss, Inc.     

Effects of Thiopental on Contractile and Electrophysiological Properties of Single Canine Left Ventricular Cells

Abstract: The effects of thiopental on contraction, membrane potential and membrane ionic currents were studied in single canine left ventricular cells. Thiopental 10^?5 and 10^?4 mol/1 reduced the cell-shortening from 7.02 ± 0.64 μm to 5.66 ± 1.39 and 3.48 ± 0.64 μm respectively (mean±S. D, N = 10, 0.5 Hz). This effect was enhanced in higher (>1.0 Hz) electrical stimulation frequencies. Also, thiopental decreased the plateau phase and shortcned the duration of action potential. On the other hand, voltage clamp experiment revealed that thiopental 10^?6, 10^?5, and 10^?4 mol/1 reduced peak Ca²⁺ current from 520±48 pA to 387 ± 60 pA, 261 ± 84 pA, and 84 ± 36 pA respectively (mean + S. D., N = 8), and showed a use-dependent block of Ca²⁺ current. However, only a high dose of thiopental (10^?4 mol/1) inhibited the Na⁴ current. We conclude that the negative inotropic effect of thiopental on the heart is mediated mainly via inhibition of the Ca²⁺ current.     

Intra- and extraluminally-applied acetylcholine on the vascular tone or the response to transmural stimulation in dog isolated mesenteric arteries

Summary Acetylcholine applied extraluminally to isolated, perfused dog mesenteric artery segments produced an endothelium-dependent depressor response when the perfusion pressure was raised by continuous infusion of noradrenaline; the potency was 1/30 to 1/60 that of intraluminal acetylcholine. Contractions induced by transmural electrical stimulation were attenuated by treatment with intra- and extraluminal acetylcholine; the inhibitory effect of intraluminal acetylcholine was greater than that of extraluminal acetylcholine. Removal of endothelium did not significantly alter the inhibitory effect. In mesenteric artery strips with endothelium, treatment with oxyhaemoglobin suppressed the relaxant response to acetylcholine but did not influence the inhibitory effect of acetylcholine on stimulation-evoked contractions. Acetylcholine reduced the ³H-overflow and contraction of superfused mesenteric artery strips, preloaded with ³H-noradrenaline, response to transmural stimulation. By the use of bioassay (dog femoral artery segment with endothelium/coronary artery strip without endothelium), the release of EDRF was first determined in the perfusate, which was introduced to dog mesenteric artery strips loaded with ³H-noradrenaline. The ³H-overflow and contraction caused by the stimulation were not attenuated by EDRF and were also observed following treatment with superoxide dismutase. Inability of the perfusate to reduce the stimulation-evoked ³H-overflow was also observed when the donor and assay tissues were treated with superoxide dismutase. It may be concluded that the inhibition by acetylcholine of the release of neuronal noradrenaline is not dependent on endothelium, Extraluminally applied acetylcholine would reach the endothelium and release EDRF, and intraluminal acetylcholine is presumed to act directly on prejunctional muscarinic receptors; however, acetylcholine appears to cross the medial layer more efficiently from intima to adventitia than in the reverse direction. Send offprint requests to N. Toda at the above address     

α2-Macroglobulin is an astroglia-derived neurite-promoting factor for cultured neurons from rat central nervous system

The neurite promoting factors in the astroglial conditioned medium (As-CM) were characterized by using primary cultures of embryonic rat neocortical neurons. The factors in the As-CM bind to lectins such as wheat germ agglutinin (WGA), suggesting that they contain sugar moieties. When the WGA-bound fractions were applied on a Superose 6 column, the activity was recovered mainly in two fractions, peak I and peak II. The peak II fraction was further purified by Mono Q anion exchange chromatography. A single protein band of 180 kDa was detected in the final Mono Q fraction by sodium dodesylsulfate polyacrylamide gel electrophoresis. The molecular weight coincided with that ofα₂-macroglobulin (α₂M). Western blotting showed that the single protein band was reacted with anti-α₂M antibody but not with anti-fibronectin and anti-laminin antisera. The neurite-promoting activity of the Mono Q fraction was inhibited by anti-α₂M antibody. Furthermore, commercially available α₂M also promotes neurite outgrowth in our assay system. These results strongly suggested that α₂M is one of the neurite-promoting factors in the As-CM.     

Topographical organization of subicular neurons projecting to subcortical regions

Direct projections from the subiculum to the septum, thalamus, and hypothalamus were studied in the rat by the fluorescent retrograde double-labeling technique with Fast blue and Diamidino yellow. The results confirm and extend the previously reported findings. The dorsal subiculum projects primarily to the lateral septum, anterior and midline thalamus, and mammillary complex. The distribution areas of cell bodies of these projection neurons are substantially segregated, depending on their target region, and few single neurons project to two of the target regions by way of axon collaterals. The ventral subiculum projects mainly to the lateral septum, midline thalamus, and ventromedial hypothalamic area. The distribution areas of cell bodies of these projection neurons are considerably overlapped with one another, and a number of single neurons send axon collaterals to two of the lateral septum, midline thalamus, and ventromedial hypothalamic area. It is, thus, indicated that the populations of subicular neurons projecting to each of the subcortical structures examined are more distinctly segregated in the dorsal subiculum than in the ventral subiculum.     

Promotive effect of 4,4''-methylenebis(N,N-dimethyl)benzenamine on N-bis(2-hydroxypropyl)nitrosamine-induced thyroid tumors in Wistar rats

The promotive effect of 4,4′-methylenebis(N,N-dimethyl)benzenamine (MDBA) on 2-stage thyroid tumorigenesis induced by N-bis(2-hydroxypropyl)nitrosamine (DHPN) in Wistar male rats was investigated. Animals were given i.p. injections of DHPN, and then a basal diet containing 0.0375% MDBA for 19 weeks. In addition, localization of the thyroid-stimulating hormone (TSH) in the pituitary gland was investigated. Levels of TSH and T4 in serum were measured by radioimmunoassay (RIA). The addition of MDBA to the diet significantly increased the incidence and numbers of preneoplastic lesion (focal hyperplasia), adenoma and carcinoma of the thyroid. TSH was usually localized in the thyroidectomy-cell in the anterior lobe of the pituitary gland, and the number of TSH-positive cells increased in the group treated with MDBA. Mean circulating levels of TSH were elevated in all MDBA-treated groups, and mean T4 levels in groups treated with MDBA were significantly lower different (P < 0.05) than those in control groups.     

Peptide synthesis by using polymer-supported N-acylphosphoramidites

Diethoxyphosphino-substituted acetamides ( 1 and 2 ) and the polymer gel bearing dialkoxy-phosphino groups ( 3,4 , and 5 ) were prepared by reaction of chlorophosphites with acetamide and crosslinked polyacrylamides, respectively, in the presence of triethylamine. By using 1,2 and the polymer as condensing reagents, various peptides were synthesized directly from N-protected amino acids and amino acid esters in high yields with little racemization. The highly crosslinked polymeric reagents simplified the procedure and were recycled by treatment with chlorophosphites.