Sympathetic terminal mediation of the acute cardiovascular response of gamma 2-MSH.
Peptides of the ACTH4-10/gamma 2-MSH3-9 class produce pressor and cardioaccelerator effects upon i.v. administration. These actions appear to be mediated by peripheral catecholamines. To ascertain the role of sympathetic nerve terminals in the cardiovascular effects of these peptides, we used bretylium tosylate to prevent nerve terminal release of norepinephrine. Pretreatment with bretylium significantly attenuated the pressor and cardioaccelerator responses of gamma 2-MSH, and shifted the peak of the remaining responses to a later time point. It appears that the acute cardiovascular response to gamma-MSH administration depends primarily on the release of sympathetic terminal norepinephrine, though some contribution from other pressor systems such as adrenal catecholamines is possible.
Callahan
M F
MF
Department of Psychology, University of Iowa, Iowa City 52242.
Kirby
R F
RF
Johnson
A K
AK
Gruber
K A
KA
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001950:Bretylium Tosylate / Q000494:pharmacology; D002319:Cardiovascular System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009411:Nerve Endings / Q000502:physiology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000502:physiology*; D013997:Time Factors
D010446:Peptide Fragments; D001950:Bretylium Tosylate; D000324:Adrenocorticotropic Hormone; C011394:ACTH (4-10)