Cardiovascular effects of microinjections of thyrotropin-releasing hormone, oxytocin and other neuropeptides into the rostral ventrolateral medulla of the rat

Thyrotropin-releasing hormone, oxytocin, neurotensin, calcitonin gene-related peptide and neuropeptide Y have been proposed as putative neurotransmitters in the rostral ventrolateral medulla of the rat. To investigate the modulation of the basal blood pressure by neuropeptides, we microinjected these neuropeptides into the rostral ventrolateral medulla of the rat and examined their effects on basal blood pressure. Male Wistar rats were anesthetized with urethane, paralyzed and artificially ventilated. Thyrotropin-releasing hormone (0.01-1 ng), oxytocin (1 and 10 ng), neurotensin (0.1-10 ng), calcitonin gene-related peptide (1 and 10 ng) and neuropeptide (1 and 10 ng) produced increases in blood pressure and/or heart rate. Ganglion blockade with hexamethonium (10 mg/kg, i.v.) blocked the pressor responses to thyrotropin-releasing hormone (0.1 ng), oxytocin (10 ng) and neurotensin (10 ng), while methylatropine (1 mg/kg, i.v.) did not affect these responses. Corticotropin-releasing factor (0.1-10 ng) and atrial natriuretic peptide (1 and 10 ng) were ineffective. These findings indicate that many neuropeptides can modify basal blood pressure when injected into the rostral ventrolateral medulla. Whether these neuropeptides play a role in the blood pressure regulation within this brain region remains to be established.

Cloning and expression of a third calcium channel beta subunit

The skeletal muscle dihydropyridine receptor/Ca2+ channel consists of five distinct subunits (alpha 1, alpha 2 delta, beta 1, and gamma). Homologous alpha 1, alpha 2 delta, and beta 2 subunits are expressed in heart and brain. The present study reports the cloning and expression of a third beta subunit, beta 3, which is expressed predominantly in brain. Its open reading frame encodes a protein with 484 amino acids with a predicted molecular mass of 54,571 Da. Coexpression of beta 3 with a cardiac alpha 1 in Xenopus oocytes induces similar changes in Ca2+ channel activity as beta 1 and beta 2, that is, it increases peak currents, modulates the voltage dependence of activation, and accelerates activation. In addition, beta 3 accelerates the rate of inactivation at positive test potentials.

Characterization and autoradiographic localization of the cannabinoid binding site in rat brain using [3H]11-OH-delta 9-THC-DMH

The binding of [3H]11-OH-delta 9-tetrahydrocannabinol-1, 1-dimethyl-heptyl (THC-DMH), a recently synthesized cannabinoid analog, was characterized in an in vitro brain slice binding assay and compared to that obtained with [3H]CP-55,940, the radiolabeled ligand used originally to characterize cannabinoid binding sites. The binding of both [3H]CP-55,940 and [3H]11-OH-delta 9-THC-DMH exhibited high affinity (Kd of 19 +/- 3 and 29 +/- 9 nM, respectively), and was saturable, reversible and specific. Values of maximal concentration of receptors determined for [3H]11-OH-delta 9-THC-DMH and [3H]CP-55,940 were 4.0 +/- 0.3 and 3.0 +/- 0.5 pmol/mg of protein, respectively. The distribution of [3H]11-OH-delta 9-THC-DMH and [3H]CP-55,940 binding in 30-microns rat brain sections was then compared by autoradiographic analysis. The binding of both ligands was densest in the basal ganglia (substantia nigra pars reticulata, globus pallidus, entopeduncular nucleus and regions of the caudate putamen) and cerebellum (molecular layer). Low levels of binding were observed in discrete brain regions including the brain stem (medulla and pons), thalamic nuclei, hypothalamus, corpus callosum and the deep nuclear layer of the cerebellum. Intermediate levels of binding were seen in layers I and VI of the cortex, and the dentate gyrus and CA pyramidal cell regions of the hippocampus. The ability of selected cannabinoid analogs to compete with [3H]11-OH-delta 9-THC-DMH binding was determined. The Ki's were correlated to the in vivo potencies for producing catalepsy, antinociception, hypothermia and decreasing spontaneous locomotor activity in mice (correlation coefficients > 0.86).(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of lipopolysaccharide on protein kinase C activity in human erythrocytes]

Membrane-associated protein kinase C activity was significantly increased after normal human erythrocytes were incubated with lipopolysaccharide. The effect was dose and time dependent. The results indicate that protein kinase C is activated by lipopolysaccharide in intact human erythrocytes.

Cloning of a novel alpha 1-subunit of the voltage-dependent calcium channel from the beta-cell

To study the molecular regulation of voltage-dependent Ca2+ channels (VDCCs) in the beta-cell, we have cloned a cDNA for the alpha 1-subunit from a hamster insulin-secreting cell line (HIT-T15). The cDNA (HCa3a) encodes a 1610-amino acid protein with four repeating membrane domains and an overall structure characteristic of other alpha 1-subunits. Although the cDNA shows a high degree of sequence homology (97%) with a rat brain alpha 1-subunit (RB alpha 1), the C-terminal 15 amino acids of HCa3a share no similarity with any cloned alpha 1 protein. High stringency Northern blot analysis revealed a single transcript of approximately 8.6 kilobases in HIT cells and hamster pancreas. A similarly sized species was detected in hamster brain, heart, and skeletal muscle. Using polymerase chain reaction and a primer set unique to HCa3a, this alpha 1 isoform was found to be expressed in islet cell lines derived from rat, mouse, and hamster. The HIT cell alpha 1-subunit is also expressed in discrete regions of the rat central nervous system, including the cortex, cerebellum, hypothalamus, and brain stem. The expression of two alpha 1 isoforms (HCa3a and cardiac) in the HIT cell underscores the possible complexity of VDCCs in the regulation of beta-cell signal transduction. With its widespread tissue distribution, HCa3a does not conform to the current classification system used for L-type VDCCs; this suggests that an alternative system of classification is required.

[Experimental studies on growing seedlings of Morinda officinalis How]

By using the techniques of growing seedlings in bowshaped shed covered with plastic sheeting plus treatment with plant growth regulator, vegetative and generative propagation tests have been made of Morinda officinalis. Scientific evidences have thus been provided for growing seedlings of Morinda officinalis.

Glucose and glucosamine regulate growth factor gene expression in vascular smooth muscle cells

We have investigated the regulation of the expression of two growth factors found in vascular smooth muscle, transforming growth factor alpha (TGF alpha) and basic fibroblast growth factor (bFGF). Cells cultured in medium containing 30 mM glucose exhibited a 2-fold increase in TGF alpha mRNA and a 3-fold increase in bFGF mRNA compared with cells grown in normal (5.5 mM) glucose. Glucosamine was more potent than glucose, leading to a 6-fold increase in TGF alpha mRNA. TGF alpha protein levels were also increased by glucosamine treatment, and the predominant species present was the membrane-bound precursor form of TGF alpha. To examine further the regulation of growth factors by sugars, cultured rat aortic smooth muscle cells were transfected with a plasmid construct consisting of a 1.2-kilobase-pair fragment of the TGF alpha promoter linked to a luciferase reporter gene. Increasing the concentration of glucose in the culture medium from 5.5 mM to 30 mM led to a rapid, 1.7-fold increase in the activity of the TGF alpha promoter. Glucosamine was much more potent than glucose in this stimulation, with 2 mM glucosamine causing a 12-fold increase in TGF alpha promoter activity. Insulin had no effect on luciferase activity in either the presence or the absence of added sugars. The glucose response element of the TGF alpha gene maps to a 130-base-pair segment that includes three potential binding sites for the transcription factor Sp1. We conclude that high glucose concentrations such as are reached in diabetes mellitus can stimulate the transcription of the genes for growth factors in vascular smooth muscle cells. This signaling pathway apparently involves the metabolism of glucose to glucosamine. This effect could be representative of nutritional regulation of a family of genes and could contribute to the toxicity of hyperglycemia and the vascular complications of diabetes.

Treatment of essential hypertension with auriculoacupressure

Auriculoacupressure was used in the treatment of 291 cases of essential hypertension, in comparison with 51 similar cases treated with Fufang Jiangya (composite hypotensive) Tablets. Analysis of results showed that the therapeutic effects in the 2 groups were similar, while the rate of marked efficacy in the acupressure group was higher than that of the medication group, and the level of blood lipids also significantly dropped (P less than 0.01); there was only minor improvement in blood rheology. In addition, acupressure manifested biphasic regulatory effects on sinus arrythmia. The curative effect of acupressure on essential vascular hypertension was good.

[Effect of nimodipine on the contraction and the Ca influx of rat aorta]

The relaxant effect of nimodipine (Nim) on rat aorta was studied in vitro. Nim inhibited KCl-induced contraction (IC50 = 40 nmol/L) more potently than NE-induced contraction (IC50 = 20 mumol/L), but did as equipotently as KCl-induced 45Ca influx (IC50 = 30 nmol/L). There was a positive correlation between inhibiting the KCl-induced 45Ca influx and the contraction (r = 0.98). However, it inhibited the NE-induced 45Ca influx (IC50 = 60 nmol/L) more potently than the NE-induced contraction. Verapamil inhibited the 2 components of NE-induced contraction significantly, while Nim only inhibited the contraction evoked by extracellular Ca2+ influx significantly. Nim did not influence the 45Ca influx into resting cells of rat aorta. These results suggest that the relaxant effect of Nim on rat aorta may be closely related to the blockade of Ca2+ entry through both potential-dependent calcium channels (PDC) and receptor-operated calcium channels (ROC), while the action on PDC seems to play a more important role than that on ROC.

Effects of site-specific mutation on structure and activity of influenza virus B/Lee/40 neuraminidase

A cDNA copy of the neuraminidase (NA) gene of a high-growing reassortant influenza virus which has the hemagglutinin of B/Hong Kong/8/73 and the NA of B/Lee/40 was cloned into plasmid pUC 9 and subcloned into a late-replacement SV40 vector so that the NA gene could be expressed in eukaryotic cells. The expressed protein was antigenically and enzymatically active. To study structure-function relationships in the B/Lee NA, particularly in comparison to the known structure of influenza A (N2) NA, specific mutations were introduced using synthetic oligonucleotides. Mutation of an apparently unpaired cysteine residue to serine at position 251 had no effect on protein transport or folding as judged by cell-surface reactivity with monoclonal antibodies, and the NA retained enzyme activity, confirming that this Cys is not essential for correct folding of the polypeptide. Mutation of Trp 364 to Leu abolished detectable enzyme activity, while mutation of Thr 368 to Val reduced enzyme activity to less than 25% of wild-type levels. Neither mutation affected antigenic properties. Therefore it is likely that both these side chains extend into the NA active site pocket. The results of these experiments are in accord with similarities in the structure of the B/Lee NA compared with that of influenza A (N2) NA. Although there is about 70% amino acid sequence difference between influenza A and B NAs, residues in the active site are highly conserved. Our in vitro mutagenesis experiments help to confirm the tentative alignment of sequences and have identified conserved amino acid side chains involved in enzyme activity.

The effect of sodium selenite on chondrocytes in monolayer culture

The effect of sodium selenite on DNA and sulfated proteoglycan synthesis by cultured rabbit articular and growth plate chondrocytes was studied as an in vitro model for Kashin-Beck disease. The selenium content of a defined medium (DMEM, fibroblast growth factor, insulin, and dexamethasone) was below the limit of detection by isotope dilution mass spectrometry. The chondrocytes were viable in the Se-free basal medium. Selenite over a range of 5 X 10(-9) M to 5 X 10(-7) M had no stimulatory effect on DNA or sulfated proteoglycan synthesis by either type of chondrocyte or skin fibroblasts. Proliferation of bovine endothelial cells was enhanced by 5 X 10(-7) M Se. At Se concentrations of greater than or equal to 10(-6) M, there was progressive inhibition of cell growth and radiosulfate incorporation of the connective tissue cells; bovine endothelial cells were more resistant. Twice equimolar concentrations of vitamins C and E exerted no protective effect against the cytotoxicity of higher concentrations of Se. Se supplementation also failed to stimulate growth of human infant chondrocytes. The model enabled simulation of conditions of hyposelenosis below those encountered in nature. The data provide no evidence that chondrocytes have idiosyncratic requirements for Se, and do not support the hypothesis that Se deficiency is a major etiologic factor in Kashin-Beck disease.

X-ray microanalysis of resting and stimulated rat pancreas

The elemental distribution in acinar cells of rat pancreas was investigated by X-ray microanalysis of thin, freeze-dried cryosections. In the resting cell, the highest calcium concentrations were found in the basal part of the cell (including the endoplasmic reticulum) and in the zymogen granules. Mitochondrial calcium concentrations were low. Zymogen granules were rich in sulphur, but low in phosphorus, sodium and potassium. Stimulation of the pancreas by perfusion in vivo with the cholinergic agonist carbachol caused a significant decrease of the calcium concentration in the basal part of the cell and an increase in the calcium concentration in the apical part of the cell. The mitochondrial calcium concentration was not significantly altered. In addition, increased sodium and decreased potassium concentrations, giving rise to a significant increase in Na/K ratio were observed in all cell compartments measured, except in the zymogen granules.

The reserpinized rat in the study of cystic fibrosis: x-ray microanalysis of submandibular gland and pancreas

The chronically reserpinized rat has been suggested as an animal model for cystic fibrosis. X-ray microanalysis of thick and thin cryosections was carried out to assess elemental redistribution in the submandibular glands and the pancreas of reserpinized rats at the cellular and subcellular level. In the submandibular gland of reserpinized rats, calcium and magnesium concentrations were significantly elevated. Mucus globules, secretory granules, and endoplasmic reticulum were the primary sites of the localization of excess calcium and magnesium. A significant potassium loss from the gland had occurred, particularly from the serous cells. Electron microscopy of conventionally prepared tissue showed marked swelling of the endoplasmic reticulum, especially in mucous cells. The elemental changes in the pancreatic acinar cells of reserpinized rats were reminiscent of elemental redistribution connected with cell death: increased levels of sodium, chlorine, and calcium and decreased levels of magnesium and potassium. Ultrastructural changes included swelling of the endoplasmic reticulum and obstruction of the acinar lumen. It is concluded tha elemental redistribution in chronically reserpinized rats presents interesting parallels with cystic fibrosis.

Cryoultramicrotomy as a preparative method for x-ray microanalysis in pathology

The role of ion shifts in cell injury has become one of the most intriguing fields of application of X-ray microanalysis in pathology. In principle, cryo(ultra)-microtomy is the best preparative method for X-ray microanalysis of diffusible substances. In this review, the following points are discussed: the choice of freezing method and coolant, the use of high molecular weight polymer cryoprotectants and their possible physiological effects the choice of the cryosectioning temperature, and techniques for handling and transfer of sections. Experiences with the sectioning of cryoprotected tissue are presented. Finally, other preparative techniques for microanalysis are compared to cryoultramicrotomy.

Immunofluorescence localizations of proteins in semithin 0.2--1 micron frozen sections of the ear. A report of improved techniques including gelatin encapsulation and cryoultramicrotomy

The present work describes a high resolution technique for locating proteins in frozen sections of the inner ear by immunofluorescence. Dissected organs are encapsulated in gelatin, and sections 0.1--1 micron thick are cut at --100 degrees C in a cryoultramicrotome. These are labelled with antibodies against two cytoskeletal proteins, actin and tubulin. Actin, which had previously only been described in the sensory cells, is found in the supporting cells as well. Tubulin is identified in the supporting cells and in outer spiral nerve fibres.