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1.
Atrial natriuretic factor alters autonomic interactions in the control of heart rate in conscious rats 总被引:2,自引:0,他引:2
U Ackermann J Khanna T G Irizawa 《Canadian journal of physiology and pharmacology》1988,66(7):930-936
Regulation of heart rate was studied in rats receiving either i.v. saline at 64 microL/min or synthetic 28-residue rat atrial natriuretic peptide (ANF) at a dose sufficient to decrease mean arterial blood pressure by 10%. Autonomic influences were deduced from steady-state heart rate responses of each group to propranolol, atropine, or propranolol and atropine combined. A multiplicative model of heart rate control was used to derive quantitatively from the data the modulation of intrinsic heart rate by sympathetic and parasympathetic mechanisms. Animals receiving ANF showed a lower heart rate than control animals. This relative bradycardia was abolished by atropine. Blocking of sympathetic effects with propranolol had no effect on basal heart rate in either group, and atropinization led to significant increases in heart rate in both groups of rats. Mathematical analysis of the results showed that the bradycardia produced by ANF was due predominantly to a reduced intrinsic heart rate and to enhanced vagal inhibition of postganglionic sympathetic activity. Parasympathetic contribution to heart rate in the absence of sympathetic activity was negligible in control rats and small during ANF. We conclude that the major influences of ANF on heart rate control are a decrease of intrinsic heart rate and enhanced parasympathetic inhibition of postganglionic presynaptic sympathetic activity. 相似文献
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Wolfgang Witt Peter Hampel Klaus Böcker Angelika Mertsching 《Archives of microbiology》1989,151(2):154-158
Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 M. The inhibition by nucleotides in low concentrations is enhanced by divalent cations. 相似文献
4.
An amino acid analysis method using a commercially available analyzer that accurately quantitates protein-derived amino acids in the 10-100 pmol range is described. The method utilizes the robotic capability of the analyzer's autosampler to perform precolumn derivatization of both primary and secondary amino acids with o-phthalaldehyde and 9-fluorenylmethyl chloroformate, respectively. The derivatized amino acids are then separated on a C-18 reverse-phase amino acid column and quantitated in a single run by fluorescence detection. The characterization of beta-lactoglobulin and two tryptic peptides from the bacterial enzyme diaminopimelic acid epimerase is used to demonstrate the sensitivity and utility of this method. 相似文献
5.
Dori R. Germolec Robert R. Maronpot Michael F. Ackermann Stephen J. Vore Kathleen Dittrich Gary J. Rosenthal Michael I. Luster 《Cancer immunology, immunotherapy : CII》1988,27(2):121-127
Summary The relationship between immune function and chemically induced hepatocarcinogenesis was studied employing an in vivo murine model. Neonatal B6C3F1 mice were given a single carcinogenic dose of diethylnitrosamine (DEN) and the time-response kinetics for the early (foci of alteration) and late (adenomas/carcinomas) phases of hepatocellular carcinogenesis were compared to changes in hematopoiesis and immune functions associated with immune surveillance and natural resistance. Increases in hematopoiesis occurred just prior to or concurrent with the appearance of hepatocellular carcinomas, while increased macrophage and natural killer cell cytotoxicity and suppression of cell-mediated immunity occurred following tumor appearance and progressed with increasing tumor burden. Neither immunological nor hematopoietic changes were associated with early phases of hepatocarcinogenesis, as monitored by the appearance of altered hepatocellular foci. Although changes in hematopoiesis may represent an early indicator for hepatocarcinogenesis in the mouse tumor model, the data suggest that altered immune surveillance and natural resistance are not factors in the development of chemically induced hepatocellular tumors, and the changes in immune function are probably secondary to tumor development. 相似文献
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Construction and properties of a viable herpes simplex virus 1 recombinant lacking coding sequences of the alpha 47 gene. 总被引:20,自引:14,他引:6
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The five alpha genes, alpha 0, alpha 4, alpha 22, alpha 27, and alpha 47, are the first set of herpes simplex virus 1 genes to be transcribed and expressed in productively infected cells. We report here the construction of a viral recombinant from which all of the coding sequences of the alpha 47 gene were deleted. In addition to the alpha 47 protein, infected cell lysates did not contain detectable amounts of two polypeptide bands with apparent molecular weights of 18,000 and 21,000 which could be specified by a gene whose regulatory domain and 5' transcribed noncoding sequences overlap with the coding sequences of the alpha 47 gene. The alpha 47- virus grew as well as the wild-type parent virus in Vero, baby hamster kidney, and Rat-1 cell lines. 相似文献
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Continuous cultures, established 10 days after pollination from endosperms of inbred A636 Zea mays (L.) were extracted 21 months later with aqueous ethanol. The solubilized proteins were analyzed by poly-acrylamide-sodium dodecyl sulfate gel electrophoresis. Two protein bands co-migrated with zein, the major storage protein of maize. Immunoblotting of the gel followed by incubation of the immobilized proteins with anti-zein IgG provided evidence that the polypeptides were in fact zein. Electron microscopic studies showed that the cultures contained cells with protein bodies as found in developing endosperms. The protein bodies could be isolated from the cultures and were shown to contain zein. We conclude that the long term cultures described here synthesize zein and deposit it in the form of protein bodies of the type found in developing endosperms. Thus, certain endosperm characteristics and the production of tissue-specific proteins are retained in prolonged culture. 相似文献
10.
Germline integration of moloney murine leukemia virus at the Mov13 locus leads to recessive lethal mutation and early embryonic death 总被引:33,自引:0,他引:33
Rudolf Jaenisch Klaus Harbers Angelika Schnieke Jürgen Löhler Ilya Chumakov Detlev Jähner Doris Grotkopp Evelyn Hoffmann 《Cell》1983,32(1):209-216
Thirteen mouse substrains genetically transmitting the exogenous Moloney murine leukemia virus (M-MuLV) at a single locus (Mov locus) have been derived previously. Experiments were performed to investigate whether homozygosity at the Mov loci would be compatible with normal development. Animals heterozygous at an Mov locus were mated, and the genotype of the offspring was analyzed. From parents heterozygous at the loci Mov1 to Mov12, respectively, homozygous offspring were obtained with the expected Mendelian frequency. In contrast, no homozygous offspring or embryos older than day 15 of gestation were obtained from parents heterozygous at the Mov13 locus. When pregnant Mov13 females at day 13 and day 14 of gestation were analyzed, approximately 25% of the embryos were degenerated. Genotyping revealed that these degenerated embryos were invariably homozygous and the normal appearing embryos were either heterozygous or negative for M-MuLV. These results suggest that integration of M-MuLV at the Mov13 locus leads to insertion mutagenesis, resulting in embryonic arrest between day 12 and day 13 of gestation. It is possible that the Mov13 locus represents a gene or gene complex involved in the early embryonic development of the mouse. 相似文献