Supraspinal administration of [D-Met2]FMRFamide produces a naloxone-sensitive increase in heart rate in unrestrained spontaneously hypertensive rats.
Intracerebroventricular (i.c.v.) administration of either Phe-Met-Arg-Phe-NH2 (FMRFamide; molluscan cardioexcitatory neuropeptide; 3-30 micrograms) or the FMRFamide analog Phe-D-Met-Arg-Phe-NH2 ([D-Met2]FMRFamide; 15 micrograms) to conscious unrestrained spontaneously hypertensive rats (SHR) produced a relatively long lasting (greater than 1 h) increase in heart rate. The increase in heart rate produced by [D-Met2]FMRFamide was attenuated by i.c.v. injection of the opiate antagonist naloxone (2 micrograms). These results extend to a second endpoint an apparent opioid agonist-like (naloxone-reversible) action of [D-Met2]FMRFamide.
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Drug Discovery Research, R. W. Johnson Pharmaceutical Research Institute, Spring House, PA 19477-0776.
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Gill
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D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D019835:FMRFamide; D006339:Heart Rate / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D009479:Neuropeptides / Q000008:administration & dosage / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D051381:Rats; D011918:Rats, Inbred SHR; D012016:Reference Values; D013116:Spinal Cord / Q000502:physiology
D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009270:Naloxone; D019835:FMRFamide