Journal of Comparative Physiology B

, Volume 155, Issue 5, pp 571–575 | Cite as

Modification of vagal action on the toad heart by changes in flow

  • Gillian P. Courtice
  • D. I. McCloskey


Hearts of toads (Bufo marinus) were perfused in situ with oxygenated Ringer's solution. The flow of the perfusate was varied during periods of vagal stimulation and in the absence of vagal stimulation. Pulse interval and cardiac contraction were monitored, and results only from those animals that showed no change in pulse interval with changes in flow in the absence of vagal stimulation were used. In these animals, during vagal stimulation, cardiac slowing was greater when flow was low than when it was high. In addition, in cases where vagal stimulation caused atrio-ventricular block, the block could be reversed by an increase in flow of the perfusate. The results are consistent with flow through the heart being an important determinant of the concentration of neurally released ACh at the pacemaker sites and therefore of the effectiveness of the vagus nerve.


Vagus Nerve Vagal Stimulation Pulse Interval Sinus Venosus Tension Record 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.





Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Blinks JR (1956) Positive chronotropic effect of increasing right atrial pressure in the isolated mammalian heart. Am J Physiol 186:299–303PubMedGoogle Scholar
  2. Brooks CMcC, Lu H-H, Lange G, Mangi R, Shaw RB, Geoly K (1966) Effects of localized stretch of the sinoatrial node region of the dog heart. Am J Physiol 211:1197–1202PubMedGoogle Scholar
  3. Burnstock G (1979) The ultrastructure of autonomic cholinergic nerves and junctions. Prog Brain Res 49:3–21PubMedCrossRefGoogle Scholar
  4. Courtice GP, McCloskey DI (1983) Modification of vagal action on the toad heart by changes in flow. Proc Int Union Physiol Sci 15:350Google Scholar
  5. Dieterich HA, Loffelholz K (1977) Effect of coronary perfusion rate on the hydrolysis of exogenous and endogenous acetylcholine in the isolated heart. Naunyn-Schmiedeberg's Arch Pharmacol 296:143–148CrossRefGoogle Scholar
  6. Dieterich HA, Loffelholz K, Pompetzki H (1977) Acetylcholine overflow from isolated perfused hearts of various species in the absence of cholinesterase inhibition. Naunyn-Schmiedeberg's Arch Pharmacol 296:149–152CrossRefGoogle Scholar
  7. Dieterich HA, Lindmar R, Loffelholz K (1978) The role of choline in the release of acetylcholine in isolated hearts. Naunyn-Schmiedeberg's Arch Pharmacol 301:207–215CrossRefGoogle Scholar
  8. Hobbs LS, Hyder RI, McDowall RJS (1926) A class experiment to demonstrate the effect of load on the frog heart. J Physiol 61:19PGoogle Scholar
  9. Katz B, Miledi R (1973) The binding of acetylcholine to receptors and its removal from the synaptic cleft. J Physiol 231:549–574PubMedGoogle Scholar
  10. Kilbinger H, Loffelholz K (1976) The isolated perfused chicken heart as a tool for studying acetylcholine output in the absence of cholinesterase inhibition. J Neural Trans 38:9–14CrossRefGoogle Scholar
  11. Lange G, Lu H-H, Chang A, Brooks CMcC (1966) Effect of stretch on the isolated cat sinoatrial node. Am J Physiol 211:1192–1196PubMedGoogle Scholar
  12. Loewi O (1921) Über humorale Übertragbarkeit der Herznervenwirkung. Pflügers Arch Ges Physiol 189:239–242CrossRefGoogle Scholar
  13. Loffelholz K (1981) Release of acetylcholine in the isolated heart. Am J Physiol 240:H431-H440PubMedGoogle Scholar
  14. Ludbrook J, Graham WF (1983) Mechanical effects of right atrial pressure on heart rate in the conscious rabbit. Aust J Exp Biol Med Sci 61:675–685PubMedGoogle Scholar
  15. MacKinnon MR, Heatwole H (1981) Comparative cardiac anatomy of the Reptilia. IV. The coronary arterial circulation. J Morphol 170:1–27PubMedCrossRefGoogle Scholar
  16. McMahan UJ, Kuffler SW (1971) Visual identification of synaptic boutons on living ganglion cells and of varicosities in postganglionic axons in the heart of the frog. Proc Roy Soc Lond B 177:485–508CrossRefGoogle Scholar
  17. O'Donnell SR, Wanstall JC (1982) Pharmacological experiments demonstrate that toad (Bufo marinus) atrial beta-adrenoceptors are not identical with mammalian beta2- or beta1-adrenoceptors. Life Sci 31:701–708PubMedCrossRefGoogle Scholar
  18. Pathak CL (1958a) Effect of stretch on formation and conduction of electrical impulses in the isolated sinoauricular chamber of frog's heart. Am J Physiol 192:111–113PubMedGoogle Scholar
  19. Pathak CL (1958b) Effects of changes in intraluminal pressure on inotropic and chronotropic responses of isolated mammalian hearts. Am J Physiol 194:197–199PubMedGoogle Scholar
  20. Shelton G (1970) The effect of lung ventilation on blood flow to the lungs and body of the amphibian,Xenopus laevis. Respir Physiol 9:183–196PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 1985

Authors and Affiliations

  • Gillian P. Courtice
    • 1
  • D. I. McCloskey
    • 1
  1. 1.School of Physiology and PharmacologyUniversity of New South WalesSydneyAustralia

Personalised recommendations