TY - JOUR
T1 - Neuronal control of heart reversal in the hawkmoth Manduca sexta
AU - Dulcis, Davide
AU - Davis, Norman T.
AU - Hildebrand, John G.
N1 - Funding Information:
Acknowledgements This research was supported by a European Community/University of Cagliari Fellowship (Decreto R. 2199) awarded to D. Dulcis and a Monsanto Company grant (J.G.H). We thank Dr. Thomas Miller for his comments on an earlier version of this paper, Dr. Tom Christensen for his valuable assistance in the use of electronic equipment, Prof. A.M. Angioy for helpful discussions, Dr. A.A. Osman for insect rearing, and Heather Stein for general laboratory assistance.
PY - 2001
Y1 - 2001
N2 - Cardiograms demonstrate that heart activity of Manduca sexta changes from larva, to pupa, to adult. The larval heart has only anterograde contractions. During metamorphosis, heart activity becomes a cyclic alternation of anterograde and retrograde contractions. Thus, the adult heart has both an anterograde and a retrograde pacemaker. External stimuli also can initiate cardiac reversal. Cardiac reversal is blocked by tetrodotoxin, indicating that reversal is under neuronal control. A branch of each dorsal nerve 8 innervates the posterior chamber of the heart, the location of the anterograde pacemaker. Only retrograde contractions occur when dorsal nerves 8 are cut. Stimulation of ml-1 8 initiates anterograde contractions; when stimulation ceases, the heart reverses to retrograde contractions. These experiments indicate that the anterograde pacemaker receives neural input that makes it the dominant pacemaker. In the absence of neural input this pacemaker is inactive, and the retrograde pacemaker becomes active. Application of crustacean cardioactive peptide accelerates the heart but does not eliminate cardiac reversal. The terminal chamber of the heart is also innervated by a branch of each dorsal nerve 7; stimulation of this nerve increases the strength of contraction of the terminal chamber but has no effect on contractions of the remainder of the heart or on cardiac reversal.
AB - Cardiograms demonstrate that heart activity of Manduca sexta changes from larva, to pupa, to adult. The larval heart has only anterograde contractions. During metamorphosis, heart activity becomes a cyclic alternation of anterograde and retrograde contractions. Thus, the adult heart has both an anterograde and a retrograde pacemaker. External stimuli also can initiate cardiac reversal. Cardiac reversal is blocked by tetrodotoxin, indicating that reversal is under neuronal control. A branch of each dorsal nerve 8 innervates the posterior chamber of the heart, the location of the anterograde pacemaker. Only retrograde contractions occur when dorsal nerves 8 are cut. Stimulation of ml-1 8 initiates anterograde contractions; when stimulation ceases, the heart reverses to retrograde contractions. These experiments indicate that the anterograde pacemaker receives neural input that makes it the dominant pacemaker. In the absence of neural input this pacemaker is inactive, and the retrograde pacemaker becomes active. Application of crustacean cardioactive peptide accelerates the heart but does not eliminate cardiac reversal. The terminal chamber of the heart is also innervated by a branch of each dorsal nerve 7; stimulation of this nerve increases the strength of contraction of the terminal chamber but has no effect on contractions of the remainder of the heart or on cardiac reversal.
KW - Crustacean cardioactive peptide
KW - Dorsal vessel
KW - Metamorphosis
KW - Pacemaker
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U2 - 10.1007/s00359-001-0254-x
DO - 10.1007/s00359-001-0254-x
M3 - Article
C2 - 11800040
AN - SCOPUS:0035675584
SN - 0340-7594
VL - 187
SP - 837
EP - 849
JO - Journal of Comparative Physiology - A Sensory, Neural, and Behavioral Physiology
JF - Journal of Comparative Physiology - A Sensory, Neural, and Behavioral Physiology
IS - 10
ER -