Résumé
Interstitial cells of Cajal are responsible for rhythmic contractions of the musculature of the gastrointestinal tract and blood vessels.The existence of these cells and spontaneous rhythmicity were noticed in amphibian vein and the findings are reported in this paper.The postcaval vein was identified in the frog, Rana tigrina and was perfused with amphibian Ringer solution after isolation.Contractile activity was recorded through a tension transducer connected to a polygraph.The isolated postcaval vein showed spontaneous rhythmic activity. Addition of cold Ringer solution decreased, while warm Ringer increased, the rate of contraction. Adrenaline caused inhibition of rhythmic activity at a dosage that increased the rate of isolated sinus venosus.Sections of the postcaval vein,when stained supravitally with methylene blue, showed the presence of interstitial cells of Cajal. Photic stimulation of the vein in the presence of methylene blue led to a significant decrease in the rate of spontaneous beating of the vein.These findings indicate that the postcaval vein of frog is capable of inherent rhythmcity, which is dependent on the interstitial cells of Cajal but is independent of the sinus venosus.
Sujets)
Animaux , Solution isotonique , Lumière , Bleu de méthylène/pharmacologie , Périodicité , Ranidae/physiologie , Température , Veines/cytologieRésumé
Frogs, R. cyanophlyctis (n = 45) divided into four groups, were exposed to different feeding regimens (live guppies were used as food) such as, daily, alternate day, every fourth day and weekly feeding for 5 months, during wet months of the year (April-September). Two toe clippings were made, one at the beginning and the other at the termination of the experiment. Clipped toes were demineralized, and processed for histology. In 6 out of 45 frogs one line of arrested growth (LAG) was present in the phalangeal histology at the beginning of the experiment while, at the termination of experiment 34 out of 43 frogs exhibited one LAG each indicating that in 26 frogs LAG appeared freshly during the experimental period. The fact that LAGs are formed in regularly fed frogs suggests the humid weather/seasonal rainfall may play relatively important role than the feeding in cyclic bone growth and formation of growth marks in this frog.
Sujets)
Animaux , Constitution physique , Indice de masse corporelle , Développement osseux , Os et tissu osseux/anatomie et histologie , Climat , Comportement alimentaire/physiologie , Ranidae/physiologieRésumé
Effect of synthetic nonapeptide (Thr-Cys-Ser-Val-Ser-Glu-Trp-Gly-Ile) representing the amino acid sequence 86-94 of human seminal plasma was studied on the ovarian follicular growth in the bullfrog R. tigrina during preparatory phase of reproductive cycle. Daily (except on Sundays) injections of 10 micrograms nonapeptide for one month caused a significant increase in ovarian weight and number of second growth phase (SGP) or vitellogenic oocytes. The results suggest that the nonapeptide is biologically active in amphibians also.
Sujets)
Séquence d'acides aminés , Animaux , Femelle , Données de séquences moléculaires , Oligopeptides/composition chimique , Follicule ovarique/effets des médicaments et des substances chimiques , Fragments peptidiques/composition chimique , Ranidae/physiologie , Sperme/composition chimiqueRésumé
Vascular autonomic receptors in amphibians exhibit difference from more evolved mammalian species. Vascular perfusion studies in frog indicate constrictions by prominent muscarinic but rudimentary nicotinic constrictive regulation by cholinergic systems. Difference from classical effect-patterns of pharmacological interventions, observed in the study, make room to visualise complexity of additional regulatory mechanisms.
Sujets)
Antagonistes alpha-adrénergiques/pharmacologie , Animaux , Bloc anesthésique du système nerveux autonome , Système nerveux autonome/effets des médicaments et des substances chimiques , Vaisseaux sanguins/effets des médicaments et des substances chimiques , Choline/analogues et dérivés , Neurofibres cholinergiques/effets des médicaments et des substances chimiques , Relation dose-effet des médicaments , Interactions médicamenteuses , Esters/pharmacologie , Femelle , Ganglions du système nerveux autonome/effets des médicaments et des substances chimiques , Mâle , Modèles biologiques , Antagonistes muscariniques , Ranidae/physiologie , Vasoconstricteurs/pharmacologieSujets)
Animaux , Gonadotrophine chorionique/pharmacologie , Femelle , Hormone folliculostimulante/pharmacologie , Gonadotrophine équine/pharmacologie , Hormone de croissance/pharmacologie , Hormone lutéinisante/pharmacologie , Ovaire/effets des médicaments et des substances chimiques , Hypophyse/physiologie , Ranidae/physiologie , SaisonsSujets)
Animaux , Anura , Membre pelvien/physiologie , Larve/physiologie , Ranidae/physiologie , RégénérationRésumé
During the winter months, high doses of acetylcholine produced positive inotropic action without any chronotropic action on the perfused atropinised frog heart, in 5 out of 24 preparations. In the remaining preparations acetylcholine failed to produce any action and positive inotropic effect of acetylcholine on these preparations was noticed if they were perfused with the medium containing excess of calcium. However, the rate remained unchanged. The positive inotropic action was blocked by the local anaesthetic amethocaine and thus may be due to increased penetration of calcium into the cardiac cell.