Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Proctolin affects the activity of the cardiac ganglion, myocardium, and cardioarterial valves in Carcinus maenas hearts (1998)
    Springer
    Journal of comparative physiology 168 (1998), S. 473-482 
    Details
    ISSN: 1432-136X
    Keywords: Key words Proctolin ; Crustacean ; Crab ; Cardiac ganglion ; Myocardium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The decapod crustacean heartbeat is initiated by the cardiac ganglion and is regulated by a variety of neuronal and hormonal inputs. In this paper we examine the effects of the peptide hormone proctolin which appears to have multiple sites of action in the shore crab, Carcinus maenas. To examine some of the potential sites of proctolin action we used three heart preparations: in situ intact and open hearts, and isolated hearts. We provide evidence in support of the hypothesis that proctolin affects cardiac activity at many levels. It acts at the cardiac ganglion to modulate burst rate and at the myocardium to alter contractile force. We calculated the relationship between contractility and ganglionic output of in situ hearts as the ratio of ventricular pressure or tension to amplitude of the electromyogram or intracellular excitatory junction potential. Large proctolin-induced changes in this ratio, which could not be accounted for by ganglionic output, membrane potential or input resistance suggest direct action on the myocardium. The greater increases in ventricular pressure than in tension in the in situ hearts may reflect proctolin-induced contraction of the cardioarterial valves. Finally, proctolin can possibly influence heart rate by action on the cardioregulatory nerves of the central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050167
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Comparison of the roles of neurohormones in the regulation of blood distribution from the hearts of American and Japanese lobsters (1998)
    Springer
    Journal of comparative physiology 168 (1998), S. 483-490 
    Details
    ISSN: 1432-136X
    Keywords: Key words Cardioarterial valves ; Blood distribution ; American lobster ; Japanese lobster ; Hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The decapod cardiovascular system consists of a single ventricle that pumps blood into seven arteries; previous work has shown that the outflow distribution patterns of intact animals are variable. In the present study, flow recordings were made from pairs of arteries in semi-isolated hearts whilst different cardioactive hormones were infused into the heart. Each hormone (5-hydroxytryptamine, octopamine, dopamine, proctolin and F1) changed the outflow pattern, heart rate and ventricular pressure in a unique way. The probable sites of hormone action are the cardioarterial valves located at the origin of each artery except one, the dorsal abdominal. Outflow from the dorsal abdominal is controlled downstream by valves located at the origin of the segmental lateral arteries. The responses to a particular hormone were sometimes different between the hearts of American and Japanese lobsters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050168
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Structure and contractile properties of the ostial muscle (musculus orbicularis ostii) in the heart of the American lobster (1999)
    Springer
    Journal of comparative physiology 169 (1999), S. 529-537 
    Details
    ISSN: 1432-136X
    Keywords: Key words Contraction ; Heart ; Ostium ; Homarus americanus (Crustacea) ; AbbreviationEPSP excitatory postsynaptic potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract “Venous” blood enters the crustacean heart through bivalved ostia. Each ostium is a discrete anatomical unit that remains functional even when isolated from the heart. Muscle fibers produce overshooting action potentials that have a plateau of variable duration in response to nervous drive from the cardiac ganglion or during trains of electrical stimuli. Contractions show summation and facilitation when stimulated by trains of stimuli delivered at rates greater than 0.5 s−1 and 0.2 s−1, respectively. Contraction amplitude increases with stimulating impulse frequency and train duration. Maximum force occurs at 1.2 times the slack length. The morphology of ostial fibers resembles that of myocardial fibers. Interconnected bundles of myofilaments occur in both the ostial fibers and the myocardial fibers. In ostial and myocardial fibers, the myofilament bundles are invested by perforated sheets of sarcoplasmic reticulum, and these sheets interface with a network of sarcolemmal tubules to form dyadic interior couplings at the level of the sarcomeric H-bands. The contractile apparatus originates and terminates at intermediate junctions on the transverse cellular boundaries, and the lateral surfaces of the muscle fibers are linked by a modest number of communicating (gap) junctions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050252
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...