Identification of multiple biological factors in rabbit serum that modulate dopamine-mediated aortic constriction

A bioassay was established using freshly prepared rabbit aortic strip to monitor the effects of various biological factors contained in rabbit serum that modulate vasoconstriction. Serotonin was shown to be a major vasoconstriction modulator in rabbit serum. A rapid procedure is described for its isolation from rabbit serum by sequential gel filtration chromatography and reversed-phase HPLC using C4, C18, and C2/C18 columns with an overall cumulative yield of about 20%. It was also noted that rabbit serum contains multiple biological factors that modulate dopamine-mediated aortic contraction other than serotonin. A potent vasoconstriction inhibitor was identified in rabbit serum which appears to be a novel regulator that mediates its effect via both alpha-adrenergic and serotonin receptors.