Elevation of arterial pressure in rats by two new vertebrate peptides FLFQPQRF-NH2 and AGEGLSSPFWSLAAPQRF-NH2 which are immunoreactive to FMRF-NH2 antiserum.

We found that two recently characterized neuropeptides Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 (F-8-F-NH2) and Ala-Gly-Glu-Gly-Leu-Ser-Ser-Pro-Phe-Trp-Ser-Leu-Ala-Ala-Pro-Gln-Arg-Phe-NH2 (A-18-F-NH2) elevate mean arterial blood pressure (MAP) in conscious, unrestrained rats. The pressor activities of both agents were attenuated, but not abolished, by prior treatment with guanethidine or prazosin. These results suggest that F-8-F-NH2 and A-18-F-NH2 elevate MAP in rats by potentiating the release of catecholamines and by mechanisms independent of catecholamine release.