Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Modulatory mechanisms in the isolated internally perfused ventricle of the whelk Busycon canaliculatum.
AU - Huddart, H.
AU - Hill, R .B.
PY - 1996/7
Y1 - 1996/7
N2 - 1. 1. Isolated cannulated ventricles commenced spontaneous beating on application of perfusion pressure of 10 cm water. Complete hearts showed a fast patterned cyclical rhythm, whereas ventricles devoid of atrial material showed a continuous slow rhythm. 2. 2. Perfused ventricles were inhibited by ACh with a threshold at 10∞ mol 1−1 and arrested at 10−7 mol 1−1 and ventricles under stimulation by 5HT could be arrested by ACh at this concentration. 3. 3. Perfused ventricles were stimulated by 5HT, with threshold at 10−9 mol 1−1 and maximum at 10−5 mol 1−1. Metoclopramide was without affect on 5HT responses, but metitipine and methysergide did inhibit such responses suggesting that the 5HT receptor present possessed mixed properties of the vertebrate 5-HT1 and 5-HT2 receptor subtypes. 4. 4. Ventricles were very sensitive to the excitatory actions of FMRFamide in the 10-9 to 105 mol 1-1 range. Preparations were insensitive to GAPFLRFamide, but SCP-B was modestly excitatory (threshold 10−7 mol l−9. 5. 5. Preparations were not significantly affected by adenosine, ATP, and guanosine, but GTP was strongly excitatory at 10−7 mol 1−1 6. 6. 5HT and FMRFamide responses were additive. Preparations responded strongly to the adenylate cyclase activator forskolin and dibutyryl cAMP enhanced spontaneous contractions and 5HT responses, suggesting that the 5HT receptor may operate via a cAMP secondary mechanism. 7. 7. The IP3 inhibitor lithium (10 mmol l−1), caused slight inhibition of FMRFamide responses, suggesting that the receptor to this peptide may operate via IP3 as a second messenger. 8. 8. Neuromodulation in this preparation would appear to involve ACh as inhibitor, 5HT and FMRFamide as upregulators, with no clear roles for FMRFamide-related peptides and GTP.
AB - 1. 1. Isolated cannulated ventricles commenced spontaneous beating on application of perfusion pressure of 10 cm water. Complete hearts showed a fast patterned cyclical rhythm, whereas ventricles devoid of atrial material showed a continuous slow rhythm. 2. 2. Perfused ventricles were inhibited by ACh with a threshold at 10∞ mol 1−1 and arrested at 10−7 mol 1−1 and ventricles under stimulation by 5HT could be arrested by ACh at this concentration. 3. 3. Perfused ventricles were stimulated by 5HT, with threshold at 10−9 mol 1−1 and maximum at 10−5 mol 1−1. Metoclopramide was without affect on 5HT responses, but metitipine and methysergide did inhibit such responses suggesting that the 5HT receptor present possessed mixed properties of the vertebrate 5-HT1 and 5-HT2 receptor subtypes. 4. 4. Ventricles were very sensitive to the excitatory actions of FMRFamide in the 10-9 to 105 mol 1-1 range. Preparations were insensitive to GAPFLRFamide, but SCP-B was modestly excitatory (threshold 10−7 mol l−9. 5. 5. Preparations were not significantly affected by adenosine, ATP, and guanosine, but GTP was strongly excitatory at 10−7 mol 1−1 6. 6. 5HT and FMRFamide responses were additive. Preparations responded strongly to the adenylate cyclase activator forskolin and dibutyryl cAMP enhanced spontaneous contractions and 5HT responses, suggesting that the 5HT receptor may operate via a cAMP secondary mechanism. 7. 7. The IP3 inhibitor lithium (10 mmol l−1), caused slight inhibition of FMRFamide responses, suggesting that the receptor to this peptide may operate via IP3 as a second messenger. 8. 8. Neuromodulation in this preparation would appear to involve ACh as inhibitor, 5HT and FMRFamide as upregulators, with no clear roles for FMRFamide-related peptides and GTP.
KW - ACh
KW - Busycon canaliculatum
KW - caffeine
KW - cyclopiazonic acid
KW - dibutyryl cAMP FMRFamide
KW - forskolin
KW - GAPFLRFamide
KW - GTP
KW - 5-hydroxytryptamine
KW - lithium
KW - methysergide
KW - metitipine
KW - SCP-B
KW - ventricle
U2 - 10.1016/0306-3623(95)02111-6
DO - 10.1016/0306-3623(95)02111-6
M3 - Journal article
VL - 27
SP - 809
EP - 818
JO - General Pharmacology: The Vascular System
JF - General Pharmacology: The Vascular System
SN - 0306-3623
IS - 5
ER -