Effect of piperazine on central and peripheral cholinergic synapses of the frog

Summary The anthelmintic agent piperazine did not antagonize carbachol-induced depolarizations of the frog sartorius muscle but depressed root potentials and acetylcholine release from the frog spinal cord. We suggest that piperazine has a presynaptic site of action at central cholinergic nerve-terminals.     

Effect of piperazine on the level of phospholipids and on the activities of certain enzymes of phospholipid metabolism in human Ascaris lumbricoides.

The phospholipid level in the human parasitic nematode Ascaris lumbricoides is decreased by piperazine, by partially stimulating catabolic enzymes such as phospholipase C and partially inhibiting anabolic enzymes such as choline kinase.     

Effect of piperazine on the level of phospholipids and on the activities of certain enzymes of phospholipid metabolism in humanAscaris lumbricoides

Summary The phospholipid level in the human parasitic nematodeAscaris lumbricoides is decreased by piperazine, by partially stimulating catabolic enzymes such as phospholipase C and partially inhibiting anabolic enzymes such as choline kinase.Acknowledgment. We thank ProfessorP. A. Kurup of this Department for keen interest and helpful advice.     

Ultrastruktureller Nachweis von zwei Myofibrillentypen in den Muskelfasern des Rattenzwerchfells

Summary The ultrastructure of the diaphragm of the rat was examined with reference to the myofibrillar structure. In longitudinal sections, 2 types of myofibrils were identified, analogous to the image of myofibrils in frog twitch and slow fibres. The thin muscle cells of the rat diaphragm contain myofibrils corresponding to the myofibrils of frog slow muscle, the thick muscle cells contain myofibrils corresponding to the myofibrils of frog twitch muscle cells. The significance of these types of muscle fibres of the rat diaphragm will be discussed in the light of physiological properties in a further study.

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Mit Unterstützung des Schweizerischen Nationalfonds für die Wissenschaftliche Forschung.     

Substance P-like immunoreactive fibers in the frog taste organs

In the frog tongue, substance P(SP)-like immunoreactive fibers were consistently present in each fungiform papilla, which contained the gustatory apparatus. Numerous SP-like immunoreactive fibers were usually distributed in the periphery of the gustatory disc and formed a varicose meshwork among the ciliated cells encircling the gustatory disc. SP-like immunoreactive fibers were rarely evident inside the gustatory disc. The role of SP-containing fibers in the frog taste organ was discussed.     

Substance P-like immunoreactive fibers in the frog taste organs

Summary In the frog tongue, substance P(SP)-like immunoreactive fibers were consistently present in each fungiform papilla, which contained the gustatory apparatus. Numerous SP-like immunoreactive fibers were usually distributed in the periphery of the gustatory disc and formed a varicose meshwork among the ciliated cells encircling the gustatory disc. SP-like immunoreactive fibers were rarely evident inside the gustatory disc. The role of SP-containing fibers in the frog taste organ was discussed.     

Sarcomere shortening and tension development during 'isometric' tetanus of muscle

Laser diffraction and tension measurements from frog muscle during isometric tetanus reveal that the sarcomeres contract more rapidly than tension develops.     

The determination of extracellular space using hemoglobin

Summary The ECS of guinea-pig atria and frog sartorii can be determined using hemoglobin. For guinea-pig atria an ECS of (32.2±2.6)% wet wt for frog sartorii an ECS of (12.4±1.0)% wet wt can be measured.This work was supported by the Deutsche Forschungsgemeinschaft SFB 114 Bionach.     

Inhibitory effect of ouabain on in vitro and in vivo gastric acid secretion in the frog and the rat

The in vitro and in vivo effects of ouabain on gastric acid secretion in the frog and the rat, the 2 species known to have different sensitivity to ouabain, were studied. It was found that ouabain was a potent inhibitor of histamine-stimulated acid secretion in the isolated frog gastric mucosa. Ouabain administered i.v. at dose levels far below the lethal range also produced a marked and significant reduction of histamine-stimulated gastric acid secretion in the anesthetized frogs and rats. It is considered that the inhibitory effect of ouabain on acid secretion could be partly related to its specific antagonizing action on the Na+ -K+ -ATPase in the gastric mucosa.     

Occurrence of eddy flow in the flowing plasma space in capillary blood vessel of frog web

Summary Studies of capillary blood flow velocity by means of a laser Doppler microscope suggest the occurrence of eddy flow in the plasma space in the capillary blood vessel of frog web.     

Destruction of afferent nerve terminals in the inner ear of frog by aminooxyactic acid.

The drug aminooxyacetic acid, which inhibits GABA-transaminase, destroys the afferent nerve ending in the inner ear of the frog. The efferent nerve endings and the sensory cells are not affected.     

Biochemistry of frog ribonucleases

Frogs have unique pyrimidine base-specific RNases, with structures similar to those of turtle, iguana and chicken RNases. Among the four frog RNases discussed here, three from Rana pipiens, R. catesbeiana and R. japonica oocyte cells show anti-tumour activity, and the latter two show lectin activity towards sialic acid-rich glycoproteins. In this review, (i) we compare their unique primary structures with respect to the locations of their disulphide bridges, three-dimensional structure, base specificity and heat stability as compared with RNase A, and (ii) we summarize current knowledge about the mode of action of lectin and the antitumour activities of the three frog RNases.     

Depletion of synaptic vesicles at the frog (Rana pipiens) neuromuscular junctions by tetraphenylboron.

At the frog neuromuscular junction tetraphenylboron produced a decrease in miniature endplate potential amplitude, accompanied by a decrease in the number but not the size of synaptic vesicles.     

Destruction of afferent nerve terminals in the inner ear of frog by aminooxyacetic acid

Summary The drug aminooxyacetic acid, which inhibits GABA-transaminase, destroys the afferent nerve endings in the inner ear of the frog. The efferent nerve endings and the sensory cells are not affected.     

Chemical excitability of axons: excitatory and inhibititory effects of putative neurotransmitters and modulators on frog sciatic nerves.

The microiontophoretic administration of putative neuromodulators (acetylcholine, norepinephrine, dopamine, 2-phenylethylamine, tryptamine, histamine) triggered firing or inhibited on-going activity in isolated frog sciatic nerves.     

Inhibitory effect of ouabain on in vitro and in vivo gastric acid secretion in the frog and the rat

Summary The in vitro and in vivo effects of ouabain on gastric acid secretion in the frog and the rat, the 2 species known to have different sensitivity to ouabain, were studied. It was found that ouabain was a potent inhibitor of histamine-stimulated acid secretion in the isolated frog gastric mucosa. Ouabain administered i.v. at dose levels far below the lethal range also produced a marked and significant reduction of histamine-stimulated gastric acid secretion in the anesthetized frogs and rats. It is considered that the inhibitory effect of ouabain on acid secretion could be partly related to ist specific antagonizing action on the Na⁺-K⁺-ATPase in the gastric mucosa.     

Isoforms of soluble alpha-tubulin in oocytes and brain of the frog (genus Rana): changes during oocyte maturation

Rana oocytes have previously been shown to contain much more soluble tubulin than does the brain, suggesting different assembly and disassembly dynamics of frog oocyte tubulin compared to that in brain. By using centrifugation, SDS-PAGE, two-dimensional gel electrophoresis and Western blots, probed with anti-α-tubulin monoclonal antibodies, polymorphic α-tubulins (isoforms) were compared in brains and follicle-enclosed oocytes of northern (Rana pipiens) and southern (R. berlandieri) frogs. Oocyte tubulin in both species had isoforms with greater ranges of isoelectric point (pI) than those of brain tubulins; in particular, the oocyte tubulin pIs ranged further into the acidic region of the isoelectric-focusing gels than corresponding brain tubulin. This difference may, in part, be responsible for the previously reported assembly differences between oocyte tubulin (undetectable assembly) and brain tubulin (high assembly). Isoforms of α-tubulin with relat ively acidic pI were more abundant in northern frog brain and oocyte soluble extracts than in analogous extracts from southern frogs. Furthermore, additional acidic α-tubulin isoforms were found in progesterone-treated oocytes (i.e., eggs), indicating increased heterogeneity of acidic a-tubulin isoforms during oocyte meiotic maturation. Among northern frog oocyte soluble components fractionated on Superose-6b columns, tubulin complexes with apparent molecular mass of about 1800 kDa were found to contain acidic α-tubulin isoforms while the putative oligomeric tubulins with an apparent molecular mass of about 250 kDa contained an additional relatively basic α-tubulin isoform. The acidic α-tubulin isoforms, therefore, are proposed to be associated with cold-adaptable cells of brain and oocytes, and may also be involved in stabilization of large soluble tubulin complexes in oocytes of the northern frog. Received 1 October 2002; accepted 9 October 2002 RID="*" ID="*"Corresponding author.     

Fluorescence replication banding of frog chromosomes

To identify individual chromosomes of a frog karyotype by their fluorescence banding patterns, chromosomes were stained with actinomycin D and 4,6-diamidino-2-phenylindole (DAPI) after incorporation of BrdU during the late S-phase. The chromosomes of three Rana species which were selected for this study (R. ridibunda, R. lessonae and R. japonica) showed well-defined late replication bands. The fluorescence patterns obtained were the reverse of those produced by a 4Na-EDTA Giemsa-staining technique. Fluorescence patterns of the two water frog species (R. ridibunda and R. lessonae) were similar to each other, except for the different fluorescence of the centromeric heterochromatin, which gave extremely bright signals in R. ridibunda but no signal in R. lessonae. Experiments also showed differences between the fluorescence patterns of R. lessonae chromosome 13 in the Italian and Luxembourgian populations. These results sho w that the fluorescence replication banding using actinomycin D and DAPI is very effective in identifying individual frog chromosomes and detecting their structural changes. Received 7 June 1996; received after revision 23 July 1996; accepted 21 August 1996     

The junctions of the sinoatrial fascicle in frogs]

The demonstration of gap-junctions on frog atria muscle similar to those described on mammalian myocardium has been controversed. En bloc staining with uranyl acetate allows us to show such gap junctions on this tissue.     

The loss of biological activity of 5-hydroxytryptamine creatinine sulphate

Summary 5-Hydroxytryptamine creatinine sulphate loses its biological activity when maintained at room temperature. The loss of 5-HT activity (in stimulating sodium transport across frog skin) is greater than the loss of creatinine sulphate activity (inhibition of sodium transport).