FACILINS, A NOVEL CLASS OF BIOLOGICAL FACTORS THAT FACILITATE THE AORTIC RESPONSE TO DOPAMINE AND OTHER BIOGENIC-AMINES

Biological fluids and tissues extracts were shown to contain biologica l factors, termed facilins, that facilitate the dopamine-, adrenaline- , and serotonin-mediated aortic contraction at concentrations devoid o f any direct effect. Cyproheptadine and phentolamine antagonized the d irect contracting effect of biogenic amines, but not the facilitated c omponent of the aortic response thus indicating that the mechanism of action of facilins was unlike that of biogenic amines. Fresh schizophr enics' CSF displayed a stronger facilitating effect than normal CSF on the dopamine-mediated aortic response. This finding, however, was not confirmed with samples kept frozen for prolonged periods of time. Mul tiple molecular forms of facilins were detected in rabbit serum. Those with a high apparent molecular weight were proteinous and were neithe r insulin nor other factors known for their contracting effects on the aorta such as epidermal growth factor, transforming growth factor-bet a, and platelet-derived growth factor.