Atrial natriuretic factor alters autonomic interactions in the control of heart rate in conscious rats

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.     

Ultrastructure of oesophageal appendages ("peptonephridia") in enchytraeids (Annelida: Clitellata)

Abstract. Although the oesophageal appendages in the four enchytraeids Enchytrueus crypticus, Fredericia strinta, Buchholzia appendiculata , and Achaeta sp. are quite different from one another in shape and position, their histology and ultrastructure are basically the same. These are intestinal appendages, the lumina of which distally end blind and proximally open into the oesophagus. Almost all of the few cells in their single-layered epithelium have a microvillous, cilia-free border at the apex, facing towards the lumen, and basally comprise an extremely extensive labyrinth. The presence of the latter, composed of very thin cell processes, and of numerous mitochondria identifies the organs as energy-producing and -consuming, transport-active structures. Their possible function as a food-moistening organ or osmoregulatory organ is discussed, and they are compared with other intestinal appendages in enchytraeids and other oligochaetes.     

Genetische Und Zytologische Untersuchungen an Verschiedenen Sippen Von Oenothera Suaveolens

Ohne ZusammenfassungMit 7 Textabbildungen.In ausführlicherer Form und mit zahlreichen Abbildungen als Dissertation bei der Naturwissenschaftlichen Fakultät der Universität München eingereicht.     

Identification and partial characterization of a latent ATP,Mg-dependent protein phosphatase in rabbit skeletal muscle cytosol

Summary Fractionation of rabbit skeletal muscle cytosol on Aminohexyl-Sepharose has resulted in the identification of a latent ATP, Mg-dependent protein phosphatase whose catalytic subunit is in the active conformation, but is inhibited by the presence of more than one modulator unit. The partially purified enzyme is converted to an inactive, kinase F_A-dependent form upon incubation at 30°C unless modulator-specific polyclonal antibodies are added to the preparation. The immunoglobulins also relieve the inhibition which is responsible for the low basal phosphatase activity of the enzyme, and they counteract all of the heat-stable inhibitor activity present in the preparation. Addition of free catalytic subunit abolishes the inhibition of the latent enzyme in a dose-dependent way, but cannot prevent the inactivation process. The inactivated phosphatase and the original latent enzyme exhibit the same apparent M _r in sucrose density-gradient centrifugation (70 000) and in gel filtration (110 000).Abbreviations PMSF Phenylmethanesulphonyl Fluoride - TLCK L-l-chloro-3-(4-tosylamido)-7-amino2-heptanone-hydrochloride - TPCK L-l-chloro-3-(4-tosvlamido)-4-phenyl-2-butanone     

High-sensitivity amino acid analysis by derivatization with O-phthalaldehyde and 9-fluorenylmethyl chloroformate using fluorescence detection: applications in protein structure determination

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.     

Lack of a relationship between immune function and chemically induced hepatocarcinogenesis in B6C3F1 mice

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.