The effects of galanin and galanin fragments on cardiac-vagal action and blood pressure in the anaesthetised cat.
Galanin (GAL), 29 amino acid peptide, has previously been shown to inhibit cardiac vagal action, and to cause a fall in systemic blood pressure in anaesthetised cats, at a dose of 6.2 nmol/kg. Here, the biological activity of exogenous GAL fragments was assessed in anaesthetised cats. GAL 1-16 at a dose equimolar with the full GAL 1-29 peptide (6.2 nmol/kg) and at a dose five times the molar dose of GAL 1-29 (31 nmol/kg), was found to be biologically active although the effects were less than that of the full peptide. GAL 1-15 at doses up to 10-times the molar dose of GAL 1-29, however, was not active, suggesting that amino acid 16, isoleucine, is critical for activity. In addition, GAL 15-29 and 21-29 showed no biological activity at doses up to 10-times the molar dose of GAL 1-29. These results suggest that the N-terminal rather than the C-terminal end of the GAL molecule is the one responsible for most of GAL's biological activity in this preparation.
Ulman
L G
LG
Prince of Wales Medical Research Institute, Randwick, Sydney, Australia.
Potter
E K
EK
McCloskey
D I
DI
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002415:Cats; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D019004:Galanin; D006321:Heart / Q000187:drug effects / Q000294:innervation*; D009479:Neuropeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D014630:Vagus Nerve / Q000187:drug effects* / Q000502:physiology
D009479:Neuropeptides; D010446:Peptide Fragments; D010455:Peptides; C062019:galanin (1-16); D019004:Galanin