ROLE OF 5-HYDROXYTRYPTAMINE IN THE VASOCONSTRICTOR ACTION OF COMPOUND 48-80 IN THE RAT FEMORAL VASCULATURE

The effect of compound 48/80 on the rat femoral vasculature was examined by means of a cross‐circulation technique. Intra‐arterial injection of increasing doses (1.5 to 15 ug) of compound 48/80 caused dose‐dependent vasoconstriction preceded by transient vasodilatation. The vasoconstriction was significantly reduced in reserpine‐treated preparations and converted to vasodilatation by methysergide. When the vasoconstrictor response to a large dose (300 ug) of adenosine was abolished by repeated administration, the response to compound 48/80 remained unaltered. The present results indicate that the femoral arterial vasoconstriction by compound 48/80 in the rat is mediated by the release of 5‐hydroxytryptamine (5‐HT); this 5‐HT may be liberated from a different storage site from that released by adenosine. 1979 British Pharmacological Society