First published online December 3, 2004
Journal of Experimental Biology 207, 4663-4677 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01272
Neuronal and neurohormonal control of the heart in the stomatopod crustacean, Squilla oratoria
Hiroshi Ando1 and
Kiyoaki Kuwasawa2,*
1 Department of Oral Physiology, Matsumoto Dental University School of
Dentistry, Shiojiri 399-0781, Japan
2 Neurobiology Laboratory, Faculty of Science, Okayama University of
Science, Ridai-cho 1-1, Okayama 700-0005, Japan
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Fig. 1. Schematic drawing of the heart and bases of the arteries (dorsal view), and
the CNS (ventral view) corresponding to the body segments. AA, anterior
artery; AG1-6, 1st to 6th abdominal ganglia; Cer. G, cerebral ganglion; CG,
cardiac ganglion; CGCs, cardiac ganglion cells; LA1-15, 1st to 15th lateral
artery; PA, posterior artery; SEG, subesophageal ganglion; TG7-9, 7th to 9th
thoracic ganglia.
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Fig. 2. (Top) Schematic drawing shows the cardiac ganglion and the right (r) and
left (l) CI, CA1 and CA2 nerves joining the cardiac ganglion (CG) in the
anterior part of the heart. (A–D) Photographs of the the outlined areas
in the top diagram, showing the cardiac ganglion and cardioregulatory nerves
in the cardiac ganglion trunk (CGT) in the anterior region of the heart
stained with Methylene Blue. Neural branch (NB) from the trunk of the CG
extends to the myocardium. AA, anterior artery; LA1to LA5, The 1st to 5th
lateral arteries. Scale bars, 50 µm.
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Fig. 3. (A) Schematic drawing of the SEG. seg, segments; NR, nerve roots of SEG.
(B) Effects of stimulation of the 10th, 16th and 19th NR on ECG. The roots
were anatomically determined to contain, respectively, CI, CA1 or CA2 nerves.
The bar shows a period of repetitive stimulation. Stimulus frequencies (Hz)
are shown at the beginning of the recordings. (C) Effects of stimulations of
the 10th, 16th or 19th nerve root on heart rate. Values are means ±
S.D.; N=7 for 10th NR, N=9 for 16th NR,
N=10 for 19th NR.
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Fig. 4. (A) Orthodromically conducted impulses were recorded at the proximal
cut-stump of the CI, CA1 and CA2 nerves on the heart (orth). The impulses were
induced by stimulation of the nerve roots at the distal cut stumps of the
10th, 16th and 19th roots of the SEG, respectively. The sites of recording and
stimulation of antidromically conducted impulses (ant) were contrary to those
of orth. Five traces were superimposed in each recording. The diagrams below
show stimulation and recording on the cutting sites for CI, CA1 and CA2
(arrows) and 10th, 16th and 19th nerve roots (NR; arrowheads). The right and
left sides of the SEG are reversed. (B) Micrographs of resin cross sections of
the CI, CA1 and CA2 nerves. A single axon (a) is seen in each section. Scale
bar, 10 µm.
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Fig. 5. Micrographs of the cell bodies of CI, CA1 and CA2 neurons stained by
back-filling with Co2+ and Ni2+ ions. The schematic
drawing (right) shows their locations in the CNS. The cell body of the CI
neuron was located at a site near the midline on the side contralateral to the
10th nerve root containing the CI axon in the 1st segment. The cell bodies of
the CA1 and CA2 neurons were located at sites, near the midline on the side
ipsilateral tothe 3rd nerve root in the 3rd and 4th segments, respectively.
Scale bar, 20 µm.
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Fig. 6. (A,B) The effects of GABA (Ai) and histamine (Bi) on heartbeat of the
isolated heart. (Aii, Bii) Dose–response curves for the effects on the
heart rate and contraction force of the agents are plotted (values are means
± S.D., N=5). GABA and histamine were applied
between the arrows. Heart rate just before GABA or histamine treatment was
35.3±12.74 or 31.9±13.9, respectively. (C) The effects of
picrotoxin on cardiac inhibition induced by stimulation of the CI nerve at 70
Hz in normal saline (control; top trace), 8 min afterapplication of
10–4 mol l–1 picrotoxin (middle trace) and
30 min after washing out picrotoxin (wash; bottom trace). The bars show a
period of repetitive stimulation of the CI nerve. The effects of picrotoxin in
abolishing neurally induced cardiac inhibition and the recovery from the
effects were observed in five preparations.
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Fig. 7. Effects of 5-HT (A), DA (B), OA (C), ACh (D) and Glu (E) on heartbeat of
the isolated heart. The agents were applied between the arrows. Heart rate
just before 5-HT, DA, OA, ACh, or Glu treatment was 32.6±5.9,
44.6±9.9, 48.2±4.6, 33.8±3.9 or 36.0±4.9,
respectively. Graphs show dose–response curves for the agents (mean
± S.D., N=5). As the effects of 5-HT appeared
biphasically, inhibition (1st phase) followed by excitation (2nd phase), they
are plotted separately.
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Fig. 8. (A) Effects of JSTX on cardiac acceleration induced by stimulation of the
CA1 nerve at 3 Hz. Vertical lines show extracellularly recorded bursting
impulses of the cardiac ganglion corresponding to heartbeats. The stimulation
produced cardiac acceleration in normal saline (control; top trace). Small
fine potentials during the bars in the records are stimulus artifacts.
Application of JSTX (10–5 mol l–1) blocked
the CA1-induced acceleration at 15 min after the onset of the application
(middle trace). The stimulation of the CA1 nerve at 3 h after washing out JSTX
induced cardiac acceleration (wash; bottom trace). The bar shows a period of
repetitive stimulation. (B) Effects of JSTX on cardiac acceleration induced by
stimulation of the CA2 nerve at 10 Hz. Application of JSTX blocked the CA2
induced acceleration at 30 min after the onset of the application. The
stimulation of the CA2 nerve at 1 h after washing out JSTX induced cardiac
acceleration. Small fine potentials during the bars in the records are
stimulus artifacts.
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Fig. 9. Effects of JSTX (5x10–6 mol l–1) on
EJPs in myocardial cells. The EJPs were evoked by stimuli applied to the
cardiac ganglion trunk at 1 Hz. The EJPs in normal saline (control) were
blocked at 30 min after the onset of JSTX application
(5x10–6 mol l–1 JSTX). The EJPs
partially recovered at 120 min after washing out of JSTX (wash). The numbers
on the left side of the traces show the membrane potentials of the cardiac
muscle at the beginning of the recordings.
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Fig. 10. Photographs of CI axons in whole-mount preparations and paraffin sections
of the heart. (A) A pair of bilateral CI axons, which show GABA-like
immunoreactivity, join the cardiac ganglion in a whole-mount preparation. (B)
A CI axon running in the trunk of the cardiac ganglion showed GABA-like
immunoreactivity in a paraffin section. Scale bar, 50 µm. The diagram shows
the areas depicted in A and B.
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Fig. 11. Photographs of glutamate-like immunoreactivity in paraffin sections
obtained from the heart. Glutamate-like immunoreactivity is seen in (Ai) the
CA1 nerve and the cardiac ganglion trunk (CGT) and (Aii) the CA2 nerves on
both sides and the CGT. (B) Glutamate-like immunoreactivity in the soma of the
cardiac ganglion neuron. (C) Glutamate-like immunoreactivity in a major branch
(MB) of the cardiac ganglion extending to the myocardium. Scale bar, 50 µm.
The diagram shows the areas depicted in A–C.
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© The Company of Biologists Ltd 2004
